diff --git a/docs/Makefile b/docs/Makefile
new file mode 100644
index 00000000..d0b8f190
--- /dev/null
+++ b/docs/Makefile
@@ -0,0 +1,240 @@
+# Makefile for Sphinx documentation
+#
+
+# You can set these variables from the command line.
+SPHINXOPTS    =
+SPHINXBUILD   = sphinx-build
+PAPER         =
+BUILDDIR      = _build
+
+# User-friendly check for sphinx-build
+ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
+$(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD environment variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don\'t have Sphinx installed, grab it from http://sphinx-doc.org/)
+endif
+
+# Internal variables.
+PAPEROPT_a4     = -D latex_paper_size=a4
+PAPEROPT_letter = -D latex_paper_size=letter
+ALLSPHINXOPTS   = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
+# the i18n builder cannot share the environment and doctrees with the others
+I18NSPHINXOPTS  = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
+
+.PHONY: help
+help:
+	@echo "Please use \`make <target>' where <target> is one of"
+	@echo "  html       to make standalone HTML files"
+	@echo "  fasthtml   'fast html': to make HTML files without regenerating the API"
+	@echo "  dirhtml    to make HTML files named index.html in directories"
+	@echo "  singlehtml to make a single large HTML file"
+	@echo "  pickle     to make pickle files"
+	@echo "  json       to make JSON files"
+	@echo "  htmlhelp   to make HTML files and a HTML help project"
+	@echo "  qthelp     to make HTML files and a qthelp project"
+	@echo "  applehelp  to make an Apple Help Book"
+	@echo "  devhelp    to make HTML files and a Devhelp project"
+	@echo "  epub       to make an epub"
+	@echo "  epub3      to make an epub3"
+	@echo "  latex      to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
+	@echo "  latexpdf   to make LaTeX files and run them through pdflatex"
+	@echo "  latexpdfja to make LaTeX files and run them through platex/dvipdfmx"
+	@echo "  text       to make text files"
+	@echo "  man        to make manual pages"
+	@echo "  texinfo    to make Texinfo files"
+	@echo "  info       to make Texinfo files and run them through makeinfo"
+	@echo "  gettext    to make PO message catalogs"
+	@echo "  changes    to make an overview of all changed/added/deprecated items"
+	@echo "  xml        to make Docutils-native XML files"
+	@echo "  pseudoxml  to make pseudoxml-XML files for display purposes"
+	@echo "  linkcheck  to check all external links for integrity"
+	@echo "  doctest    to run all doctests embedded in the documentation (if enabled)"
+	@echo "  coverage   to run coverage check of the documentation (if enabled)"
+	@echo "  dummy      to check syntax errors of document sources"
+
+.PHONY: clean
+clean:
+	rm -rf $(BUILDDIR)/*
+	rm -rf modules
+
+.PHONY: html
+html:
+	sphinx-apidoc -f -l -o modules ../ereuse_devicehub
+	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
+	@echo
+	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
+
+.PHONY: fasthtml
+fasthtml:
+	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
+	@echo
+	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
+
+.PHONY: dirhtml
+dirhtml:
+	$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
+	@echo
+	@echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml."
+
+.PHONY: singlehtml
+singlehtml:
+	$(SPHINXBUILD) -b singlehtml $(ALLSPHINXOPTS) $(BUILDDIR)/singlehtml
+	@echo
+	@echo "Build finished. The HTML page is in $(BUILDDIR)/singlehtml."
+
+.PHONY: pickle
+pickle:
+	$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle
+	@echo
+	@echo "Build finished; now you can process the pickle files."
+
+.PHONY: json
+json:
+	$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json
+	@echo
+	@echo "Build finished; now you can process the JSON files."
+
+.PHONY: htmlhelp
+htmlhelp:
+	$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
+	@echo
+	@echo "Build finished; now you can run HTML Help Workshop with the" \
+	      ".hhp project file in $(BUILDDIR)/htmlhelp."
+
+.PHONY: qthelp
+qthelp:
+	$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp
+	@echo
+	@echo "Build finished; now you can run "qcollectiongenerator" with the" \
+	      ".qhcp project file in $(BUILDDIR)/qthelp, like this:"
+	@echo "# qcollectiongenerator $(BUILDDIR)/qthelp/DeviceHub.qhcp"
+	@echo "To view the help file:"
+	@echo "# assistant -collectionFile $(BUILDDIR)/qthelp/DeviceHub.qhc"
+
+.PHONY: applehelp
+applehelp:
+	$(SPHINXBUILD) -b applehelp $(ALLSPHINXOPTS) $(BUILDDIR)/applehelp
+	@echo
+	@echo "Build finished. The help book is in $(BUILDDIR)/applehelp."
+	@echo "N.B. You won't be able to view it unless you put it in" \
+	      "~/Library/Documentation/Help or install it in your application" \
+	      "bundle."
+
+.PHONY: devhelp
+devhelp:
+	$(SPHINXBUILD) -b devhelp $(ALLSPHINXOPTS) $(BUILDDIR)/devhelp
+	@echo
+	@echo "Build finished."
+	@echo "To view the help file:"
+	@echo "# mkdir -p $$HOME/.local/share/devhelp/DeviceHub"
+	@echo "# ln -s $(BUILDDIR)/devhelp $$HOME/.local/share/devhelp/DeviceHub"
+	@echo "# devhelp"
+
+.PHONY: epub
+epub:
+	$(SPHINXBUILD) -b epub $(ALLSPHINXOPTS) $(BUILDDIR)/epub
+	@echo
+	@echo "Build finished. The epub file is in $(BUILDDIR)/epub."
+
+.PHONY: epub3
+epub3:
+	$(SPHINXBUILD) -b epub3 $(ALLSPHINXOPTS) $(BUILDDIR)/epub3
+	@echo
+	@echo "Build finished. The epub3 file is in $(BUILDDIR)/epub3."
+
+.PHONY: latex
+latex:
+	$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
+	@echo
+	@echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex."
+	@echo "Run \`make' in that directory to run these through (pdf)latex" \
+	      "(use \`make latexpdf' here to do that automatically)."
+
+.PHONY: latexpdf
+latexpdf:
+	sphinx-apidoc -f -l -o . ../ereuse_devicehub
+	$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
+	@echo "Running LaTeX files through pdflatex..."
+	$(MAKE) -C $(BUILDDIR)/latex all-pdf
+	@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
+
+.PHONY: latexpdfja
+latexpdfja:
+	$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
+	@echo "Running LaTeX files through platex and dvipdfmx..."
+	$(MAKE) -C $(BUILDDIR)/latex all-pdf-ja
+	@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
+
+.PHONY: text
+text:
+	$(SPHINXBUILD) -b text $(ALLSPHINXOPTS) $(BUILDDIR)/text
+	@echo
+	@echo "Build finished. The text files are in $(BUILDDIR)/text."
+
+.PHONY: man
+man:
+	$(SPHINXBUILD) -b man $(ALLSPHINXOPTS) $(BUILDDIR)/man
+	@echo
+	@echo "Build finished. The manual pages are in $(BUILDDIR)/man."
+
+.PHONY: texinfo
+texinfo:
+	$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
+	@echo
+	@echo "Build finished. The Texinfo files are in $(BUILDDIR)/texinfo."
+	@echo "Run \`make' in that directory to run these through makeinfo" \
+	      "(use \`make info' here to do that automatically)."
+
+.PHONY: info
+info:
+	$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
+	@echo "Running Texinfo files through makeinfo..."
+	make -C $(BUILDDIR)/texinfo info
+	@echo "makeinfo finished; the Info files are in $(BUILDDIR)/texinfo."
+
+.PHONY: gettext
+gettext:
+	$(SPHINXBUILD) -b gettext $(I18NSPHINXOPTS) $(BUILDDIR)/locale
+	@echo
+	@echo "Build finished. The message catalogs are in $(BUILDDIR)/locale."
+
+.PHONY: changes
+changes:
+	$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes
+	@echo
+	@echo "The overview file is in $(BUILDDIR)/changes."
+
+.PHONY: linkcheck
+linkcheck:
+	$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck
+	@echo
+	@echo "Link check complete; look for any errors in the above output " \
+	      "or in $(BUILDDIR)/linkcheck/output.txt."
+
+.PHONY: doctest
+doctest:
+	$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
+	@echo "Testing of doctests in the sources finished, look at the " \
+	      "results in $(BUILDDIR)/doctest/output.txt."
+
+.PHONY: coverage
+coverage:
+	$(SPHINXBUILD) -b coverage $(ALLSPHINXOPTS) $(BUILDDIR)/coverage
+	@echo "Testing of coverage in the sources finished, look at the " \
+	      "results in $(BUILDDIR)/coverage/python.txt."
+
+.PHONY: xml
+xml:
+	$(SPHINXBUILD) -b xml $(ALLSPHINXOPTS) $(BUILDDIR)/xml
+	@echo
+	@echo "Build finished. The XML files are in $(BUILDDIR)/xml."
+
+.PHONY: pseudoxml
+pseudoxml:
+	$(SPHINXBUILD) -b pseudoxml $(ALLSPHINXOPTS) $(BUILDDIR)/pseudoxml
+	@echo
+	@echo "Build finished. The pseudo-XML files are in $(BUILDDIR)/pseudoxml."
+
+.PHONY: dummy
+dummy:
+	$(SPHINXBUILD) -b dummy $(ALLSPHINXOPTS) $(BUILDDIR)/dummy
+	@echo
+	@echo "Build finished. Dummy builder generates no files."
diff --git a/docs/conf.py b/docs/conf.py
new file mode 100644
index 00000000..d8b26965
--- /dev/null
+++ b/docs/conf.py
@@ -0,0 +1,300 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# DeviceHub documentation build configuration file, created by
+# sphinx-quickstart on Mon Apr 18 16:40:20 2016.
+#
+# This file is execfile()d with the current directory set to its
+# containing dir.
+#
+# Note that not all possible configuration values are present in this
+# autogenerated file.
+#
+# All configuration values have a default; values that are commented out
+# serve to show the default.
+
+import os
+import sys
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+sys.path.insert(0, os.path.abspath('../ereuse_devicehub'))
+
+# -- General configuration ------------------------------------------------
+
+# If your documentation needs a minimal Sphinx version, state it here.
+needs_sphinx = '1.4.7'
+
+# Add any Sphinx extension module names here, as strings. They can be
+# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
+# ones.
+extensions = [
+    'sphinx.ext.autodoc',
+    'sphinx.ext.intersphinx',
+    'sphinx.ext.todo',
+    'sphinx.ext.viewcode',
+    'sphinxcontrib.httpdomain',
+    'sphinx.ext.todo'
+]
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# The suffix(es) of source filenames.
+# You can specify multiple suffix as a list of string:
+# source_suffix = ['.rst', '.md']
+source_suffix = '.rst'
+
+# The encoding of source files.
+# source_encoding = 'utf-8-sig'
+
+# The master toctree document.
+master_doc = 'index'
+
+# General information about the project.
+project = 'DeviceHub'
+copyright = '2017, eReuse.org team'
+author = 'eReuse.org team'
+
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
+#
+# The short X.Y version.
+version = '0.1'
+# The full version, including alpha/beta/rc tags.
+release = '0.1'
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#
+# This is also used if you do content translation via gettext catalogs.
+# Usually you set "language" from the command line for these cases.
+language = None
+
+# There are two options for replacing |today|: either, you set today to some
+# non-false value, then it is used:
+# today = ''
+# Else, today_fmt is used as the format for a strftime call.
+# today_fmt = '%B %d, %Y'
+
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+# This patterns also effect to html_static_path and html_extra_path
+exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
+
+# The reST default role (used for this markup: `text`) to use for all
+# documents.
+# default_role = None
+
+# If true, '()' will be appended to :func: etc. cross-reference text.
+# add_function_parentheses = True
+
+# If true, the current module name will be prepended to all description
+# unit titles (such as .. function::).
+add_module_names = False
+
+# If true, sectionauthor and moduleauthor directives will be shown in the
+# output. They are ignored by default.
+# show_authors = False
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = 'sphinx'
+
+# A list of ignored prefixes for module index sorting.
+# modindex_common_prefix = []
+
+# If true, keep warnings as "system message" paragraphs in the built documents.
+# keep_warnings = False
+
+# If true, `todo` and `todoList` produce output, else they produce nothing.
+todo_include_todos = True
+
+# -- Options for HTML output ----------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+html_theme = 'alabaster'
+
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+# html_theme_options = {}
+
+# Add any paths that contain custom themes here, relative to this directory.
+# html_theme_path = []
+
+# The name for this set of Sphinx documents.
+# "<project> v<release> documentation" by default.
+# html_title = 'DeviceHub v0.1'
+
+# A shorter title for the navigation bar.  Default is the same as html_title.
+# html_short_title = None
+
+# The name of an image file (relative to this directory) to place at the top
+# of the sidebar.
+# html_logo = None
+
+# The name of an image file (relative to this directory) to use as a favicon of
+# the docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
+# pixels large.
+# html_favicon = None
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['_static']
+
+# Add any extra paths that contain custom files (such as robots.txt or
+# .htaccess) here, relative to this directory. These files are copied
+# directly to the root of the documentation.
+# html_extra_path = []
+
+# If not None, a 'Last updated on:' timestamp is inserted at every page
+# bottom, using the given strftime format.
+# The empty string is equivalent to '%b %d, %Y'.
+# html_last_updated_fmt = None
+
+# If true, SmartyPants will be used to convert quotes and dashes to
+# typographically correct entities.
+# html_use_smartypants = True
+
+# Custom sidebar templates, maps document names to template names.
+# html_sidebars = {}
+
+# Additional templates that should be rendered to pages, maps page names to
+# template names.
+# html_additional_pages = {}
+
+# If false, no module index is generated.
+# html_domain_indices = True
+
+# If false, no index is generated.
+# html_use_index = True
+
+# If true, the index is split into individual pages for each letter.
+html_split_index = True
+
+# If true, links to the reST sources are added to the pages.
+# html_show_sourcelink = True
+
+# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
+# html_show_sphinx = True
+
+# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
+# html_show_copyright = True
+
+# If true, an OpenSearch description file will be output, and all pages will
+# contain a <link> tag referring to it.  The value of this option must be the
+# base URL from which the finished HTML is served.
+# html_use_opensearch = ''
+
+# This is the file name suffix for HTML files (e.g. ".xhtml").
+# html_file_suffix = None
+
+# Language to be used for generating the HTML full-text search index.
+# Sphinx supports the following languages:
+#   'da', 'de', 'en', 'es', 'fi', 'fr', 'h', 'it', 'ja'
+#   'nl', 'no', 'pt', 'ro', 'r', 'sv', 'tr', 'zh'
+# html_search_language = 'en'
+
+# A dictionary with options for the search language support, empty by default.
+# 'ja' uses this config value.
+# 'zh' user can custom change `jieba` dictionary path.
+# html_search_options = {'type': 'default'}
+
+# The name of a javascript file (relative to the configuration directory) that
+# implements a search results scorer. If empty, the default will be used.
+# html_search_scorer = 'scorer.js'
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = 'DeviceHubdoc'
+
+# -- Options for LaTeX output ---------------------------------------------
+
+latex_elements = {
+    # The paper size ('letterpaper' or 'a4paper').
+    # 'papersize': 'letterpaper',
+
+    # The font size ('10pt', '11pt' or '12pt').
+    # 'pointsize': '10pt',
+
+    # Additional stuff for the LaTeX preamble.
+    # 'preamble': '',
+
+    # Latex figure (float) alignment
+    # 'figure_align': 'htbp',
+}
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title,
+#  author, documentclass [howto, manual, or own class]).
+latex_documents = [
+    (master_doc, 'DeviceHub.tex', 'DeviceHub Documentation',
+     'eReuse.org team', 'manual'),
+]
+
+# The name of an image file (relative to this directory) to place at the top of
+# the title page.
+# latex_logo = None
+
+# For "manual" documents, if this is true, then toplevel headings are parts,
+# not chapters.
+# latex_use_parts = False
+
+# If true, show page references after internal links.
+# latex_show_pagerefs = False
+
+# If true, show URL addresses after external links.
+# latex_show_urls = False
+
+# Documents to append as an appendix to all manuals.
+# latex_appendices = []
+
+# If false, no module index is generated.
+# latex_domain_indices = True
+
+
+# -- Options for manual page output ---------------------------------------
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+man_pages = [
+    (master_doc, 'devicehub', 'DeviceHub Documentation',
+     [author], 1)
+]
+
+# If true, show URL addresses after external links.
+# man_show_urls = False
+
+
+# -- Options for Texinfo output -------------------------------------------
+
+# Grouping the document tree into Texinfo files. List of tuples
+# (source start file, target name, title, author,
+#  dir menu entry, description, category)
+texinfo_documents = [
+    (master_doc, 'DeviceHub', 'DeviceHub Documentation',
+     author, 'DeviceHub', 'One line description of project.',
+     'Miscellaneous'),
+]
+
+# Documents to append as an appendix to all manuals.
+# texinfo_appendices = []
+
+# If false, no module index is generated.
+# texinfo_domain_indices = True
+
+# How to display URL addresses: 'footnote', 'no', or 'inline'.
+# texinfo_show_urls = 'footnote'
+
+# If true, do not generate a @detailmenu in the "Top" node's menu.
+# texinfo_no_detailmenu = False
+
+
+# Example configuration for intersphinx: refer to the Python standard library.
+intersphinx_mapping = {'https://docs.python.org/': None}
+
+autodoc_default_flags = ['members', 'private-members']
+autodoc_member_order = 'bysource'
diff --git a/docs/index.rst b/docs/index.rst
new file mode 100644
index 00000000..a8ba6321
--- /dev/null
+++ b/docs/index.rst
@@ -0,0 +1,20 @@
+..  Dependencies: sphinx sphinxcontrib-httpdomain
+..  title:: DeviceHub
+
+.. image:: https://www.ereuse.org/files/2017/04/DeviceHub-logo-V2.svg
+   :height: 100px
+   :alt: DeviceHub logo
+
+This is the documentation and API of the
+`eReuse.org DeviceHub <https://github.com/eReuse/DeviceHub>`_.
+
+..  toctree::
+    :maxdepth: 4
+
+    snapshot
+
+
+* :ref:`genindex`
+* :ref:`modindex`
+
+.. image::
\ No newline at end of file
diff --git a/docs/snapshot.rst b/docs/snapshot.rst
new file mode 100644
index 00000000..6c72c2cc
--- /dev/null
+++ b/docs/snapshot.rst
@@ -0,0 +1,23 @@
+Snapshot
+========
+The Snapshot updates the state of the device with information about its components and events
+performed at them.
+
+When receiving a Snapshot, the DeviceHub creates, adds and removes components to match the
+Snapshot. For example, if a Snapshot of a computer contains a new component, the system will
+search for the component in its database and, if not found, create it, and finally adding it
+to the computer.
+
+Snapshots can bundle some events, usually tests and hard-drive erasures. In such case the
+DeviceHub will save those events.
+
+A Snapshot is used with Remove to represent changes in components for a device:
+1. A device is created in the database always with a Snapshot. If this device had components,
+   they are created (if they did not existed before) in the same time with the same Snapshot.
+2. Time after, a new Snapshot updates component information. If, for example, this new Snasphot
+   doesn't have a component, it means that this component is not present anymore in the device,
+   thus removing it from it. Then we have that:
+     - Components to add: snapshot2.components - snapshot1.components
+     - Components to remove: snapshot1.components - snapshot2.components
+   When adding a component, there may be the case this component existed before and it was
+   inside another device. In such case, DeviceHub will perform ``Remove`` on the old parent.
diff --git a/ereuse_devicehub/config.py b/ereuse_devicehub/config.py
index 87ea0b1e..1bde47b3 100644
--- a/ereuse_devicehub/config.py
+++ b/ereuse_devicehub/config.py
@@ -3,7 +3,8 @@ from distutils.version import StrictVersion
 from ereuse_devicehub.resources.device import ComponentDef, ComputerDef, DesktopDef, DeviceDef, \
     GraphicCardDef, HardDriveDef, LaptopDef, MicrotowerDef, MotherboardDef, NetbookDef, \
     NetworkAdapterDef, ProcessorDef, RamModuleDef, ServerDef
-from ereuse_devicehub.resources.event import EventDef, SnapshotDef
+from ereuse_devicehub.resources.event import EventDef, SnapshotDef, TestDef, TestHardDriveDef, \
+    AddDef, RemoveDef
 from ereuse_devicehub.resources.user import UserDef
 from teal.config import Config
 
@@ -12,7 +13,8 @@ class DevicehubConfig(Config):
     RESOURCE_DEFINITIONS = (
         DeviceDef, ComputerDef, DesktopDef, LaptopDef, NetbookDef, ServerDef, MicrotowerDef,
         ComponentDef, GraphicCardDef, HardDriveDef, MotherboardDef, NetworkAdapterDef,
-        RamModuleDef, ProcessorDef, UserDef, EventDef, SnapshotDef
+        RamModuleDef, ProcessorDef, UserDef, EventDef, AddDef, RemoveDef, SnapshotDef,
+        TestDef, TestHardDriveDef
     )
     PASSWORD_SCHEMES = {'pbkdf2_sha256'}
     SQLALCHEMY_DATABASE_URI = 'postgresql://localhost/dh-db1'
diff --git a/ereuse_devicehub/resources/device/models.py b/ereuse_devicehub/resources/device/models.py
index 5a73c6e0..f9801b17 100644
--- a/ereuse_devicehub/resources/device/models.py
+++ b/ereuse_devicehub/resources/device/models.py
@@ -1,4 +1,5 @@
 from contextlib import suppress
+from operator import attrgetter
 from typing import Dict, Set
 
 from ereuse_utils.naming import Naming
@@ -28,6 +29,14 @@ class Device(Thing):
     height = Column(Float(precision=3, decimal_return_scale=3),
                     check_range('height', 0.1, 3))  # type: float
 
+    @property
+    def events(self) -> list:
+        """All the events performed to the device."""
+        # Tried to use chain() but Marshmallow doesn't like it :-(
+        events = self.events_multiple + self.events_one
+        events.sort(key=attrgetter('id'))
+        return events
+
     def __init__(self, *args, **kw) -> None:
         super().__init__(*args, **kw)
         with suppress(TypeError):
@@ -59,14 +68,17 @@ class Device(Thing):
         extensions/declarative/api.html
         #sqlalchemy.ext.declarative.declared_attr>`_
         """
-        args = {POLYMORPHIC_ID: cls.__name__}
-        if cls.__name__ == 'Device':
+        args = {POLYMORPHIC_ID: cls.t}
+        if cls.t == 'Device':
             args[POLYMORPHIC_ON] = cls.type
         return args
 
     def __lt__(self, other):
         return self.id < other.id
 
+    def __repr__(self) -> str:
+        return '<{0.t} {0.id!r} model={0.model!r} S/N={0.serial_number!r}>'.format(self)
+
 
 class Computer(Device):
     id = Column(BigInteger, ForeignKey(Device.id), primary_key=True)  # type: int
@@ -97,7 +109,10 @@ class Component(Device):
 
     parent_id = Column(BigInteger, ForeignKey('computer.id'))
     parent = relationship(Computer,
-                          backref=backref('components', lazy=True, cascade=CASCADE),
+                          backref=backref('components',
+                                          lazy=True,
+                                          cascade=CASCADE,
+                                          order_by=lambda: Component.id),
                           primaryjoin='Component.parent_id == Computer.id')  # type: Device
 
     def similar_one(self, parent: Computer, blacklist: Set[int]) -> 'Component':
@@ -119,19 +134,29 @@ class Component(Device):
             raise ResourceNotFound(self.type)
         return component
 
+    @property
+    def events(self) -> list:
+        events = super().events
+        events.extend(self.events_components)
+        events.sort(key=attrgetter('id'))
+        return events
 
-class GraphicCard(Component):
-    id = Column(BigInteger, ForeignKey(Component.id), primary_key=True)  # type: int
+
+class JoinedComponentTableMixin:
+    @declared_attr
+    def id(cls):
+        return Column(BigInteger, ForeignKey(Component.id), primary_key=True)
+
+
+class GraphicCard(JoinedComponentTableMixin, Component):
     memory = Column(SmallInteger, check_range('memory', min=1, max=10000))  # type: int
 
 
-class HardDrive(Component):
-    id = Column(BigInteger, ForeignKey(Component.id), primary_key=True)  # type: int
+class HardDrive(JoinedComponentTableMixin, Component):
     size = Column(Integer, check_range('size', min=1, max=10 ** 8))  # type: int
 
 
-class Motherboard(Component):
-    id = Column(BigInteger, ForeignKey(Component.id), primary_key=True)  # type: int
+class Motherboard(JoinedComponentTableMixin, Component):
     slots = Column(SmallInteger, check_range('slots'))  # type: int
     usb = Column(SmallInteger, check_range('usb'))  # type: int
     firewire = Column(SmallInteger, check_range('firewire'))  # type: int
@@ -139,19 +164,16 @@ class Motherboard(Component):
     pcmcia = Column(SmallInteger, check_range('pcmcia'))  # type: int
 
 
-class NetworkAdapter(Component):
-    id = Column(BigInteger, ForeignKey(Component.id), primary_key=True)  # type: int
+class NetworkAdapter(JoinedComponentTableMixin, Component):
     speed = Column(SmallInteger, check_range('speed', min=10, max=10000))  # type: int
 
 
-class Processor(Component):
-    id = Column(BigInteger, ForeignKey(Component.id), primary_key=True)  # type: int
+class Processor(JoinedComponentTableMixin, Component):
     speed = Column(Float, check_range('speed', 0.1, 15))
     cores = Column(SmallInteger, check_range('cores', 1, 10))
     address = Column(SmallInteger, check_range('address', 8, 256))
 
 
-class RamModule(Component):
-    id = Column(BigInteger, ForeignKey(Component.id), primary_key=True)  # type: int
+class RamModule(JoinedComponentTableMixin, Component):
     size = Column(SmallInteger, check_range('size', min=128, max=17000))
     speed = Column(Float, check_range('speed', min=100, max=10000))
diff --git a/ereuse_devicehub/resources/device/schemas.py b/ereuse_devicehub/resources/device/schemas.py
index eeb0a8a5..2d77c97e 100644
--- a/ereuse_devicehub/resources/device/schemas.py
+++ b/ereuse_devicehub/resources/device/schemas.py
@@ -1,4 +1,3 @@
-from marshmallow import post_dump
 from marshmallow.fields import Float, Integer, Str
 from marshmallow.validate import Length, OneOf, Range
 
@@ -32,16 +31,6 @@ class Device(Thing):
                    unit=UnitCodes.m,
                    description='The height of the device in meters.')
     events = NestedOn('Event', many=True, dump_only=True)
-    events_one = NestedOn('Event', many=True, dump_only=True, description='Not used.')
-    events_components = NestedOn('Event', many=True, dump_only=True, description='Not used.')
-
-    @post_dump
-    def merge_events(self, data: dict) -> dict:
-        if isinstance(data.get('events_one', None), list):
-            data.setdefault('events', []).extend(data.pop('events_one'))
-        if isinstance(data.get('events_components', None), list):
-            data.setdefault('events', []).extend(data.pop('events_components'))
-        return data
 
 
 class Computer(Device):
diff --git a/ereuse_devicehub/resources/device/sync.py b/ereuse_devicehub/resources/device/sync.py
index 6a43bae7..cb98beb8 100644
--- a/ereuse_devicehub/resources/device/sync.py
+++ b/ereuse_devicehub/resources/device/sync.py
@@ -158,22 +158,17 @@ class Sync:
                            be re-added.
         :return: A list of Add / Remove events.
         """
+        # Note that we create the Remove events before the Add ones
         events = []
         old_components = set(device.components)
+
         adding = components - old_components
         if adding:
-            add = Add(device=device, components=list(adding))
-
             # For the components we are adding, let's remove them from their old parents
             def g_parent(component: Component) -> int:
                 return component.parent or Computer(id=0)  # Computer with id 0 is our Identity
 
-            for parent, _components in groupby(sorted(add.components, key=g_parent), key=g_parent):
-                if parent.id != 0:
+            for parent, _components in groupby(sorted(adding, key=g_parent), key=g_parent):
+                if parent.id != 0:  # Is not Computer Identity
                     events.append(Remove(device=parent, components=list(_components)))
-            events.append(add)
-
-        removing = old_components - components
-        if removing:
-            events.append(Remove(device=device, components=list(removing)))
         return events
diff --git a/ereuse_devicehub/resources/device/views.py b/ereuse_devicehub/resources/device/views.py
index eff67a45..c8b90009 100644
--- a/ereuse_devicehub/resources/device/views.py
+++ b/ereuse_devicehub/resources/device/views.py
@@ -6,9 +6,9 @@ class DeviceView(View):
     def one(self, id: int):
         """Gets one device."""
         device = Device.query.filter_by(id=id).one()
-        return self.schema.jsonify_polymorphic(device)
+        return self.schema.jsonify(device)
 
     def find(self, args: dict):
         """Gets many devices"""
         devices = Device.query.all()
-        return self.schema.jsonify_polymorphic_many(devices)
+        return self.schema.jsonify(devices, many=True)
diff --git a/ereuse_devicehub/resources/event/__init__.py b/ereuse_devicehub/resources/event/__init__.py
index f71056ab..827b87a7 100644
--- a/ereuse_devicehub/resources/event/__init__.py
+++ b/ereuse_devicehub/resources/event/__init__.py
@@ -1,4 +1,5 @@
-from ereuse_devicehub.resources.event.schemas import Snapshot, Event
+from ereuse_devicehub.resources.event.schemas import Add, Event, Remove, Snapshot, Test, \
+    TestHardDrive
 from ereuse_devicehub.resources.event.views import EventView, SnapshotView
 from teal.resource import Converters, Resource
 
@@ -10,6 +11,22 @@ class EventDef(Resource):
     ID_CONVERTER = Converters.int
 
 
+class AddDef(EventDef):
+    SCHEMA = Add
+
+
+class RemoveDef(EventDef):
+    SCHEMA = Remove
+
+
 class SnapshotDef(EventDef):
     SCHEMA = Snapshot
     VIEW = SnapshotView
+
+
+class TestDef(EventDef):
+    SCHEMA = Test
+
+
+class TestHardDriveDef(TestDef):
+    SCHEMA = TestHardDrive
diff --git a/ereuse_devicehub/resources/event/models.py b/ereuse_devicehub/resources/event/models.py
index 3c05104c..cb4e758b 100644
--- a/ereuse_devicehub/resources/event/models.py
+++ b/ereuse_devicehub/resources/event/models.py
@@ -10,7 +10,7 @@ from sqlalchemy.orm import backref, relationship, validates
 from sqlalchemy_utils import ColorType
 
 from ereuse_devicehub.db import db
-from ereuse_devicehub.resources.device.models import Device
+from ereuse_devicehub.resources.device.models import Component, Device
 from ereuse_devicehub.resources.event.enums import Appearance, Bios, Functionality, Orientation, \
     SoftwareType, StepTypes, TestHardDriveLength
 from ereuse_devicehub.resources.models import STR_BIG_SIZE, STR_SIZE, STR_SM_SIZE, Thing, \
@@ -49,10 +49,12 @@ class Event(Thing):
     author = relationship(User,
                           backref=backref('events', lazy=True),
                           primaryjoin=author_id == User.id)
-
-    components = relationship(Device,
-                              backref=backref('events_components', lazy=True),
-                              secondary=lambda: EventComponent.__table__)
+    components = relationship(Component,
+                              backref=backref('events_components',
+                                              lazy=True,
+                                              order_by=lambda: Event.id),
+                              secondary=lambda: EventComponent.__table__,
+                              order_by=lambda: Device.id)
 
     @declared_attr
     def __mapper_args__(cls):
@@ -63,8 +65,8 @@ class Event(Thing):
         extensions/declarative/api.html
         #sqlalchemy.ext.declarative.declared_attr>`_
         """
-        args = {POLYMORPHIC_ID: cls.__name__}
-        if cls.__name__ == 'Event':
+        args = {POLYMORPHIC_ID: cls.t}
+        if cls.t == 'Event':
             args[POLYMORPHIC_ON] = cls.type
         if JoinedTableMixin in cls.mro():
             args[INHERIT_COND] = cls.id == Event.id
@@ -79,17 +81,29 @@ class EventComponent(db.Model):
 class EventWithOneDevice(Event):
     device_id = Column(BigInteger, ForeignKey(Device.id), nullable=False)
     device = relationship(Device,
-                          backref=backref('events_one', lazy=True, cascade=CASCADE),
+                          backref=backref('events_one',
+                                          lazy=True,
+                                          cascade=CASCADE,
+                                          order_by=lambda: EventWithOneDevice.id),
                           primaryjoin=Device.id == device_id)
 
+    def __repr__(self) -> str:
+        return '<{0.t} {0.id!r} device={0.device!r}>'.format(self)
+
 
 class EventWithMultipleDevices(Event):
     """
     Note that these events are not deleted when a device is deleted.
     """
     devices = relationship(Device,
-                           backref=backref('events', lazy=True),
-                           secondary=lambda: EventDevice.__table__)
+                           backref=backref('events_multiple',
+                                           lazy=True,
+                                           order_by=lambda: EventWithMultipleDevices.id),
+                           secondary=lambda: EventDevice.__table__,
+                           order_by=lambda: Device.id)
+
+    def __repr__(self) -> str:
+        return '<{0.t} {0.id!r} devices={0.devices!r}>'.format(self)
 
 
 class EventDevice(db.Model):
@@ -192,6 +206,7 @@ class Test(JoinedTableMixin, EventWithOneDevice):
 
 
 class TestHardDrive(Test):
+    id = Column(BigInteger, ForeignKey(Test.id), primary_key=True)
     length = Column(DBEnum(TestHardDriveLength), nullable=False)  # todo from type
     status = Column(Unicode(STR_SIZE), nullable=False)
     lifetime = Column(Interval, nullable=False)
diff --git a/ereuse_devicehub/resources/event/schemas.py b/ereuse_devicehub/resources/event/schemas.py
index cbb716d0..1e131688 100644
--- a/ereuse_devicehub/resources/event/schemas.py
+++ b/ereuse_devicehub/resources/event/schemas.py
@@ -30,7 +30,7 @@ class Event(Thing):
                                   'hardware without margin of doubt.')
     incidence = Boolean(default=False,
                         description='Was something wrong in this event?')
-    snapshot = NestedOn('Snapshot', dump_only=True, only='id')
+    snapshot = NestedOn('Snapshot', dump_only=True)
     description = String(default='', description='A comment about the event.')
     components = NestedOn(Component, dump_only=True, many=True)
 
@@ -40,7 +40,7 @@ class EventWithOneDevice(Event):
 
 
 class EventWithMultipleDevices(Event):
-    device = NestedOn(Device, many=True, only='id')
+    devices = NestedOn(Device, many=True, only='id')
 
 
 class Add(EventWithOneDevice):
@@ -124,8 +124,19 @@ class Inventory(Schema):
 
 
 class Snapshot(EventWithOneDevice):
+    """
+    The Snapshot updates the state of the device with information about
+    its components and events performed at them.
+
+    See docs for more info.
+    """
     device = NestedOn(Device)  # todo and when dumping?
-    components = NestedOn(Component, many=True)
+    components = NestedOn(Component,
+                          many=True,
+                          description='A list of components that are inside of the device'
+                                      'at the moment of this Snapshot.'
+                                      'Order is preserved, so the component num 0 when'
+                                      'submitting is the component num 0 when returning it back.')
     uuid = UUID(required=True)
     version = Version(required=True, description='The version of the SnapshotSoftware.')
     software = EnumField(SoftwareType,
@@ -138,7 +149,7 @@ class Snapshot(EventWithOneDevice):
     color = Color(description='Main color of the device.')
     orientation = EnumField(Orientation, description='Is the device main stand wider or larger?')
     force_creation = Boolean(data_key='forceCreation')
-    events = NestedOn(Event, many=True)
+    events = NestedOn(Event, many=True, dump_only=True)
 
     @validates_schema
     def validate_workbench_version(self, data: dict):
diff --git a/ereuse_devicehub/resources/event/views.py b/ereuse_devicehub/resources/event/views.py
index 28f9edf6..d838b49d 100644
--- a/ereuse_devicehub/resources/event/views.py
+++ b/ereuse_devicehub/resources/event/views.py
@@ -12,7 +12,8 @@ from teal.resource import View
 class EventView(View):
     def one(self, id: int):
         """Gets one event."""
-        return Event.query.filter_by(id=id).one()
+        event = Event.query.filter_by(id=id).one()
+        return self.schema.jsonify(event)
 
 
 SUPPORTED_WORKBENCH = StrictVersion('11.0')
@@ -20,7 +21,11 @@ SUPPORTED_WORKBENCH = StrictVersion('11.0')
 
 class SnapshotView(View):
     def post(self):
-        """Creates a Snapshot."""
+        """
+        Performs a Snapshot.
+
+        See `Snapshot` section in docs for more info.
+        """
         s = request.get_json()
         # Note that if we set the device / components into the snapshot
         # model object, when we flush them to the db we will flush
@@ -31,8 +36,18 @@ class SnapshotView(View):
         snapshot = Snapshot(**s)
         snapshot.device, snapshot.events = Sync.run(device, components, snapshot.force_creation)
         snapshot.components = snapshot.device.components
+        # commit will change the order of the components by what
+        # the DB wants. Let's get a copy of the list so we preserve
+        # order
+        ordered_components = [c for c in snapshot.components]
         db.session.add(snapshot)
-        db.session.flush()  # Take to DB so we get db-generated values
+        db.session.commit()
+        # todo we are setting snapshot dirty again with this components but
+        # we do not want to update it.
+        # The real solution is https://stackoverflow.com/questions/
+        # 24480581/set-the-insert-order-of-a-many-to-many-sqlalchemy-
+        # flask-app-sqlite-db?noredirect=1&lq=1
+        snapshot.components = ordered_components
         ret = self.schema.jsonify(snapshot)  # transform it back
         ret.status_code = 201
         return ret
diff --git a/ereuse_devicehub/resources/user/models.py b/ereuse_devicehub/resources/user/models.py
index b59e49e8..f7ea7926 100644
--- a/ereuse_devicehub/resources/user/models.py
+++ b/ereuse_devicehub/resources/user/models.py
@@ -24,3 +24,6 @@ class User(Thing):
     """
     name = Column(Unicode(length=STR_SIZE))
     token = Column(UUID(as_uuid=True), default=uuid4, unique=True)
+
+    def __repr__(self) -> str:
+        return '<{0.t} {0.id!r} email={0.email!r}>'.format(self)
diff --git a/tests/files/2-second-device-with-components-of-first.snapshot.yaml b/tests/files/2-second-device-with-components-of-first.snapshot.yaml
index 1ed31f01..e0333ee8 100644
--- a/tests/files/2-second-device-with-components-of-first.snapshot.yaml
+++ b/tests/files/2-second-device-with-components-of-first.snapshot.yaml
@@ -10,7 +10,14 @@ components:
     type: 'Motherboard'
   - manufacturer: 'p1c2m'
     serialNumber: 'p1c2s'
-    model: 'p1'
+    model: 'p1c2'
     speed: 1.23
     cores: 2
     type: 'Processor'
+condition:
+  appearance: 'A'
+  functionality: 'B'
+elapsed: 25
+software: 'Workbench'
+uuid: 'f2e02261-87a1-4a50-b9b7-92c0e476e5f2'
+version: '11.0'
\ No newline at end of file
diff --git a/tests/files/3-first-device-but-removing-motherboard-and-adding-processor-from-2.snapshot.yaml b/tests/files/3-first-device-but-removing-motherboard-and-adding-processor-from-2.snapshot.yaml
index 935d83b7..968eda05 100644
--- a/tests/files/3-first-device-but-removing-motherboard-and-adding-processor-from-2.snapshot.yaml
+++ b/tests/files/3-first-device-but-removing-motherboard-and-adding-processor-from-2.snapshot.yaml
@@ -1,5 +1,5 @@
 device:
-  manufactuer: 'p1'
+  manufacturer: 'p1'
   serialNumber: 'p1'
   model: 'p1'
   type: 'Desktop'
@@ -7,11 +7,18 @@ secured: False
 components:
   - manufacturer: 'p1c2m'
     serialNumber: 'p1c2s'
-    model: 'p1'
+    model: 'p1c2'
     type: 'Processor'
     cores: 2
     speed: 1.23
   - manufacturer: 'p1c3m'
     serialNumber: 'p1c3s'
     type: 'GraphicCard'
-    memory: 1.5
\ No newline at end of file
+    memory: 1.5
+condition:
+  appearance: 'C'
+  functionality: 'C'
+elapsed: 30
+software: 'Workbench'
+uuid: '3be271b6-5ef4-47d8-8237-5e1133eebfc6'
+version: '11.0'
\ No newline at end of file
diff --git a/tests/files/4-first-device-but-removing-processor.snapshot-and-adding-graphic-card.yaml b/tests/files/4-first-device-but-removing-processor.snapshot-and-adding-graphic-card.yaml
index a86a8842..451ddd14 100644
--- a/tests/files/4-first-device-but-removing-processor.snapshot-and-adding-graphic-card.yaml
+++ b/tests/files/4-first-device-but-removing-processor.snapshot-and-adding-graphic-card.yaml
@@ -1,5 +1,5 @@
 device:
-  manufactuer: 'p1'
+  manufacturer: 'p1'
   serialNumber: 'p1'
   model: 'p1'
   type: 'Desktop'
@@ -12,4 +12,11 @@ components:
   - manufacturer: 'p1c3m'
     serialNumber: 'p1c3s'
     type: 'GraphicCard'
-    memory: 1.5
\ No newline at end of file
+    memory: 1.5
+condition:
+  appearance: 'A'
+  functionality: 'A'
+elapsed: 25
+software: 'Workbench'
+uuid: 'fd007eb4-48e3-454a-8763-169491904c6e'
+version: '11.0'
\ No newline at end of file
diff --git a/tests/test_device.py b/tests/test_device.py
index 72302aae..bdad607e 100644
--- a/tests/test_device.py
+++ b/tests/test_device.py
@@ -1,3 +1,6 @@
+from datetime import timedelta
+from uuid import UUID
+
 import pytest
 
 from ereuse_devicehub.client import UserClient
@@ -8,7 +11,8 @@ from ereuse_devicehub.resources.device.models import Component, Computer, Deskto
     GraphicCard, Laptop, Microtower, Motherboard, NetworkAdapter
 from ereuse_devicehub.resources.device.schemas import Device as DeviceS
 from ereuse_devicehub.resources.device.sync import Sync
-from ereuse_devicehub.resources.event.models import Add, Remove
+from ereuse_devicehub.resources.event.models import Remove, Test
+from ereuse_devicehub.resources.user import User
 from teal.db import ResourceNotFound
 from tests.conftest import file
 
@@ -58,7 +62,7 @@ def test_device_schema():
     """Ensures the user does not upload non-writable or extra fields."""
     device_s = DeviceS()
     device_s.load({'serialNumber': 'foo1', 'model': 'foo', 'manufacturer': 'bar2'})
-    device_s.dump({'id': 1})
+    device_s.dump(Device(id=1))
 
 
 @pytest.mark.usefixtures('app_context')
@@ -132,16 +136,12 @@ def test_add_remove():
     # Test:
     # pc has only c3
     events = Sync.add_remove(device=pc, components={c3, c4})
-    assert len(events) == 3
+    db.session.add_all(events)
+    db.session.commit()  # We enforce the appliance of order_by
+    assert len(events) == 1
     assert isinstance(events[0], Remove)
     assert events[0].device == pc2
     assert events[0].components == [c3]
-    assert isinstance(events[1], Add)
-    assert events[1].device == pc
-    assert set(events[1].components) == {c3, c4}
-    assert isinstance(events[2], Remove)
-    assert events[2].device == pc
-    assert set(events[2].components) == {c1, c2}
 
 
 @pytest.mark.usefixtures('app_context')
@@ -185,9 +185,19 @@ def test_get_device(app: Devicehub, user: UserClient):
             GraphicCard(model='c2mo', manufacturer='c2ma', memory=1500)
         ]
         db.session.add(pc)
+        db.session.add(Test(device=pc,
+                            elapsed=timedelta(seconds=4),
+                            success=True,
+                            author=User(email='bar@bar.com')))
         db.session.commit()
     pc, _ = user.get(res=Device, item=1)
-    assert pc['events'] == []
+    assert len(pc['events']) == 1
+    assert pc['events'][0]['type'] == 'Test'
+    assert pc['events'][0]['id'] == 1
+    assert pc['events'][0]['device'] == 1
+    assert pc['events'][0]['elapsed'] == 4
+    assert pc['events'][0]['success'] == True
+    assert UUID(pc['events'][0]['author'])
     assert 'events_components' not in pc, 'events_components are internal use only'
     assert 'events_one' not in pc, 'they are internal use only'
     assert 'author' not in pc
diff --git a/tests/test_snapshot.py b/tests/test_snapshot.py
index 59bded42..abf1dbc6 100644
--- a/tests/test_snapshot.py
+++ b/tests/test_snapshot.py
@@ -8,8 +8,8 @@ from ereuse_devicehub.client import UserClient
 from ereuse_devicehub.db import db
 from ereuse_devicehub.devicehub import Devicehub
 from ereuse_devicehub.resources.device.models import Device, Microtower
-from ereuse_devicehub.resources.event.models import Appearance, Bios, Functionality, Snapshot, \
-    SnapshotRequest, SoftwareType
+from ereuse_devicehub.resources.event.models import Appearance, Bios, Event, Functionality, \
+    Snapshot, SnapshotRequest, SoftwareType
 from ereuse_devicehub.resources.user.models import User
 from tests.conftest import file
 
@@ -36,18 +36,28 @@ def assert_similar_components(components1: List[dict], components2: List[dict]):
 
 def snapshot_and_check(user: UserClient,
                        input_snapshot: dict,
-                       num_events: int = 0,
+                       event_types: tuple or list = tuple(),
                        perform_second_snapshot=True) -> dict:
     """
-
+        P
     """
     snapshot, _ = user.post(res=Snapshot, data=input_snapshot)
-    assert len(snapshot['events']) == num_events
+    assert tuple(e['type'] for e in snapshot['events']) == event_types
+    # Ensure there is no Remove event after the first Add
+    found_add = False
+    for event in snapshot['events']:
+        if event['type'] == 'Add':
+            found_add = True
+        if found_add:
+            assert event['type'] != 'Receive', 'All Remove events must be before the Add ones'
     assert input_snapshot['device']
     assert_similar_device(input_snapshot['device'], snapshot['device'])
     assert_similar_components(input_snapshot['components'], snapshot['components'])
+    assert all(c['parent'] == snapshot['device']['id'] for c in snapshot['components']), \
+        'Components must be in their parent'
     if perform_second_snapshot:
-        return snapshot_and_check(user, input_snapshot, num_events, False)
+        input_snapshot['uuid'] = uuid4()
+        return snapshot_and_check(user, input_snapshot, perform_second_snapshot=False)
     else:
         return snapshot
 
@@ -99,7 +109,7 @@ def test_snapshot_post(user: UserClient):
     Tests the post snapshot endpoint (validation, etc)
     and data correctness.
     """
-    snapshot = snapshot_and_check(user, file('basic.snapshot'))
+    snapshot = snapshot_and_check(user, file('basic.snapshot'), perform_second_snapshot=False)
     assert snapshot['software'] == 'Workbench'
     assert snapshot['version'] == '11.0'
     assert snapshot['uuid'] == 'f5efd26e-8754-46bc-87bf-fbccc39d60d9'
@@ -111,9 +121,104 @@ def test_snapshot_post(user: UserClient):
 
 
 def test_snapshot_add_remove(user: UserClient):
-    s1 = file('1-device-with-components.snapshot')
-    snapshot_and_check(user, s1)
+    def get_events_info(events: List[dict]) -> tuple:
+        return tuple(
+            (
+                e['id'],
+                e['type'],
+                [c['serialNumber'] for c in e['components']],
+                e.get('snapshot', {}).get('id', None)
+            )
+            for e in (user.get(res=Event, item=e['id'])[0] for e in events)
+        )
 
+    # We add the first device (2 times). The distribution of components
+    # (represented with their S/N) should be:
+    # PC 1: p1c1s, p1c2s, p1c3s. PC 2: ø
+    s1 = file('1-device-with-components.snapshot')
+    snapshot1 = snapshot_and_check(user, s1, perform_second_snapshot=False)
+    pc1_id = snapshot1['device']['id']
+    pc1, _ = user.get(res=Device, item=pc1_id)
+    # Parent contains components
+    assert tuple(c['serialNumber'] for c in pc1['components']) == ('p1c1s', 'p1c2s', 'p1c3s')
+    # Components contain parent
+    assert all(c['parent'] == pc1_id for c in pc1['components'])
+    # pc has Snapshot as event
+    assert len(pc1['events']) == 1
+    assert pc1['events'][0]['type'] == Snapshot.t
+    # p1c1s has Snapshot
+    p1c1s, _ = user.get(res=Device, item=pc1['components'][0]['id'])
+    assert tuple(e['type'] for e in p1c1s['events']) == ('Snapshot',)
+
+    # We register a new device
+    # It has the processor of the first one (p1c2s)
+    # PC 1: p1c1s, p1c3s. PC 2: p2c1s, p1c2s
+    # Events PC1: Snapshot, Remove. PC2: Snapshot
     s2 = file('2-second-device-with-components-of-first.snapshot')
+    # num_events = 2 = Remove, Add
+    snapshot2 = snapshot_and_check(user, s2, event_types=('Remove', ),
+                                   perform_second_snapshot=False)
+    pc2_id = snapshot2['device']['id']
+    pc1, _ = user.get(res=Device, item=pc1_id)
+    pc2, _ = user.get(res=Device, item=pc2_id)
+    # PC1
+    assert tuple(c['serialNumber'] for c in pc1['components']) == ('p1c1s', 'p1c3s')
+    assert all(c['parent'] == pc1_id for c in pc1['components'])
+    assert tuple(e['type'] for e in pc1['events']) == ('Snapshot', 'Remove')
+    # PC2
+    assert tuple(c['serialNumber'] for c in pc2['components']) == ('p1c2s', 'p2c1s')
+    assert all(c['parent'] == pc2_id for c in pc2['components'])
+    assert tuple(e['type'] for e in pc2['events']) == ('Snapshot', )
+    # p1c2s has two Snapshots, a Remove and an Add
+    p1c2s, _ = user.get(res=Device, item=pc2['components'][0]['id'])
+    assert tuple(e['type'] for e in p1c2s['events']) == ('Snapshot', 'Snapshot', 'Remove')
+
+    # We register the first device again, but removing motherboard
+    # and moving processor from the second device to the first.
+    # We have created 1 Remove (from PC2's processor back to PC1)
+    # PC 0: p1c2s, p1c3s. PC 1: p2c1s
     s3 = file('3-first-device-but-removing-motherboard-and-adding-processor-from-2.snapshot')
+    snapshot_and_check(user, s3, ('Remove', ), perform_second_snapshot=False)
+    pc1, _ = user.get(res=Device, item=pc1_id)
+    pc2, _ = user.get(res=Device, item=pc2_id)
+    # PC1
+    assert {c['serialNumber'] for c in pc1['components']} == {'p1c2s', 'p1c3s'}
+    assert all(c['parent'] == pc1_id for c in pc1['components'])
+    assert get_events_info(pc1['events']) == (
+        # id, type, components, snapshot
+        (1, 'Snapshot', ['p1c1s', 'p1c2s', 'p1c3s'], None),  # first Snapshot1
+        (3, 'Remove', ['p1c2s'], 2),  # Remove Processor in Snapshot2
+        (4, 'Snapshot', ['p1c2s', 'p1c3s'], None)  # This Snapshot3
+    )
+    # PC2
+    assert tuple(c['serialNumber'] for c in pc2['components']) == ('p2c1s',)
+    assert all(c['parent'] == pc2_id for c in pc2['components'])
+    assert tuple(e['type'] for e in pc2['events']) == (
+        'Snapshot',  # Second Snapshot
+        'Remove'  # the processor we added in 2.
+    )
+    # p1c2s has Snapshot, Remove and Add
+    p1c2s, _ = user.get(res=Device, item=pc1['components'][0]['id'])
+    assert get_events_info(p1c2s['events']) == (
+        (1, 'Snapshot', ['p1c1s', 'p1c2s', 'p1c3s'], None),  # First Snapshot to PC1
+        (2, 'Snapshot', ['p1c2s', 'p2c1s'], None),  # Second Snapshot to PC2
+        (3, 'Remove', ['p1c2s'], 2),  # ...which caused p1c2s to be removed form PC1
+        (4, 'Snapshot', ['p1c2s', 'p1c3s'], None),  # The third Snapshot to PC1
+        (5, 'Remove', ['p1c2s'], 4)  # ...which caused p1c2 to be removed from PC2
+    )
+
+    # We register the first device but without the processor,
+    # adding a graphic card and adding a new component
     s4 = file('4-first-device-but-removing-processor.snapshot-and-adding-graphic-card')
+    snapshot_and_check(user, s4, perform_second_snapshot=False)
+    pc1, _ = user.get(res=Device, item=pc1_id)
+    pc2, _ = user.get(res=Device, item=pc2_id)
+    # PC 0: p1c3s, p1c4s. PC1: p2c1s
+    assert {c['serialNumber'] for c in pc1['components']} == {'p1c3s', 'p1c4s'}
+    assert all(c['parent'] == pc1_id for c in pc1['components'])
+    # This last Snapshot only
+    assert get_events_info(pc1['events'])[-1] == (6, 'Snapshot', ['p1c3s', 'p1c4s'], None)
+    # PC2
+    # We haven't changed PC2
+    assert tuple(c['serialNumber'] for c in pc2['components']) == ('p2c1s',)
+    assert all(c['parent'] == pc2_id for c in pc2['components'])