equivalent-xml

Description

Problem

Testing XML output is difficult:

• Comparing text output is brittle due to the vagaries of serialization.
• Attribute order doesn't matter.
• Element order matters sometimes, but not always.
• Text sometimes needs to be normalized, but CDATA doesn't.
• Nodes in the same namespace don't always use the same prefix
• Etc.

Solution

EquivalentXml for Nokogiri

Use

EquivalentXml.equivalent?(node_1, node_2, opts = { :element_order => false, :normalize_whitespace => true }) { |n1, n2, result| ... }

node_1 and node_2 can be any Nokogiri::XML::Node descendants (or any string containing an XML document or document fragment). The most common use case is to compare two Nokogiri::XML::Document instances.

node_1 is equivalent to node_2 if and only if:

• node_1 and node_2 are of the same class
• node_1 and node_2 are in the same namespace
• node_1 and node_2 have the same number of child nodes (excluding ProcessingInstructions, Comments and empty Text nodes)
• For each child of node_1, there is exactly one equal child of node_2
• If called with :element_order => true, equivalent child elements must be in the same relative position in order to be considered equal

If a block is given, the block will be called every time two nodes are compared. The parameters will be the two nodes being compared as well as the result of the comparison. If the block explicitly returns true or false (a real TrueClass or FalseClass, not just an expression that can be coerced to true or false), the return value will override the result of the comparison.

Element nodes are equivalent if they have the same name, and their child nodesets are equal (as defined above)

Attribute nodes are equivalent if their names and values match exactly

CDATA nodes are equivalent if their text strings match exactly, including leading, trailing, and internal whitespace

Non-CDATA CharacterData nodes are equivalent if their text strings match after stripping leading and trailing whitespace and collapsing internal whitespace to a single space

Document nodes are equivalent if their root nodes are equal

ProcessingInstruction and Comment nodes are ignored

Options

:element_order => true

Require elements to be in the same relative position in order to be considered equivalent.

:normalize_whitespace => false

Don't normalize whitespace within text nodes; require text nodes to match exactly.

:ignore_content => ["Device > SerialNumber", "Device > ICCID"]

A single CSS selector, or an array of CSS selectors, of nodes for which the content (text and child nodes) should be ignored when comparing for equivalence. Defaults to nil. (Uses Nokogiri's Node#css(*rules) to conduct the search.)

Using with RSpec

EquivalentXml includes a custom matcher for RSpec (version >=1.2.4) that makes including XML equivalencies in your spec tests a cinch!

Add below two line to spec_helper.rb:

require 'rspec/matchers' # req by equivalent-xml custom matcher `be_equivalent_to`
require 'equivalent-xml'

Equivalency:

expect(node_1).to be_equivalent_to(node_2)
expect(node_1).not_to be_equivalent_to(node_2)

Chained modifiers:

expect(node_1).to be_equivalent_to(node_2).respecting_element_order
expect(node_1).to be_equivalent_to(node_2).with_whitespace_intact
expect(node_1).to be_equivalent_to(node_2).respecting_element_order.with_whitespace_intact
expect(node_1).to be_equivalent_to(node_2).ignoring_content_of("SerialNumber")

Contributing to equivalent-xml

• Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet
• Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it
• Fork the project
• Start a feature/bugfix branch
• Commit and push until you are happy with your contribution
• Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

History

• 0.5.1 - Fix false negative when comparing a Nokogiri::XML::Node to a string (introduced in 0.5.0)
• 0.5.0 - Allow to compare XML-Fragments in Strings (contrib. by webmasters)
• 0.4.4 - Fix rspec 3 deprecation warnings while maintaining compatibility with rspec 1 & 2 (w/assist from barelyknown & DanielHeath)
• 0.4.3 - Updates for rspec 3
• 0.4.2 - Move version back into gemspec for now
• 0.4.1 - Improved RSpec version checking (contrib. by elandesign)
• 0.4.0 - Added :ignore_attr_values option (contrib. by ivannovosad)
• 0.3.0 - Added :ignore_content option (contrib. by moklett)
• 0.2.9 - Fix for rspec-rails >= 2.7 (contrib. by jcoyne)
• 0.2.8 - Allow comparison against nodesets (contrib. by gkellogg)
• 0.2.7 - Auto-require RSpec matchers if RSpec is loaded
• 0.2.6 - Added documentation for RSpec matchers
• 0.2.5 - Added YARD documentation
• 0.2.4 - Fixed comparison of non-XML input
• 0.2.3 - Improved handling of non-XML input
• 0.2.2 - Dependency update
• 0.2.1 - Hotfix: Missing files in gemspec
• 0.2.0 - Custom rspec matchers
• 0.1.6 - Allow caller to override comparison result in block
• 0.1.5 - Allow XML documents to be passed as strings, re-instituting dependency on nokogiri
• 0.1.4 - Hotfix: Missing block parameter on compare_nodesets()
• 0.1.3 - Hotfix: Missing block parameter on compare_nodesets()
• 0.1.2 - Yield evaluated nodes and provisional result if block given
• 0.1.1 - Removed explicit runtime dependency on nokogiri
• 0.1.0 - Initial release

Copyright

Copyright (c) 2011-14 Michael B. Klein. See LICENSE.txt for further details.