Comparing XML

A simple XML comparison can be performed using XmlCompare.compare:

// using XML literals:
val result = XmlCompare.compare(<test/>, <test/>) // == XmlEqual

// or from a file:
val success = XmlCompare.compare(<result><success/></result>, XML.loadFile("result.xml"))

The way that XML is compared can be customised by supplying DiffOptions:

// this would result an XmlEqual
XmlCompare.compare(
  <test name="John" age="45"/>,
  <test age="45" name="John"/>)

// this would result an XmlDiffers
XmlCompare.compare(
  <test name="John" age="45"/>,
  <test age="45" name="John"/>,
  DiffOptions(DiffOption.StrictAttributeOrdering))

Comparison Options contains details of the supported options.

Comparison Results

XmlCompare.compare returns an XmlDiff that will either be XmlEqual or a detailed XmlDiffers. If a simple pass/fail check is required then the isEqual method can be called on the result.

XmlEqual

An XmlEqual result signifies that no differences in the XML were found.

XmlDiffers

An XmlDiffers result will contain the first difference found in the XML. The reason property will have a human-readable reason for the difference, left & right will have the differences and failurePath will have the path segments to the difference.

For example:

XmlDiffers(
  "different attribute ordering",
  Seq("first", "second"),
  Seq("second", "first"),
  Seq("test")
)

Comparison Options

Building Options

Options can built by either passing them into DiffOptions()) or by combining them:

// these two are equivalent:
DiffOptions(DiffOption.IgnoreNamespacePrefix, DiffOption.IgnoreNamespace)
DiffOptions(DiffOption.IgnoreNamespacePrefix) & DiffOption.IgnoreNamespace

Default Options

The default options (unspecified or DiffOptions.default) are:

• IgnoreNamespacePrefix

Available Options

IgnoreNamespacePrefix

If enabled the prefixes associated with namespaces will be ignored. Differing namespaces will still cause a comparison error.

Example

This:

<t:example xmlns:t="http://example.com">5</t:example>

would be considered equal to:

<f:example xmlns:f="http://example.com">5</f:example>

IgnoreNamespace

If enabled then namespaces will be ignored completely.

Example

This:

<t:example xmlns:t="http://example.com">5</t:example>

would be considered equal to:

<f:example xmlns:f="http://example.org">5</f:example>

StrictAttributeOrdering

This adds an additional comparison on the ordering of element attributes. The presence of attributes will be checked before the ordering.

Example

This:

<example first="a" second="b" />

would not be equal to:

<example second="b" first="a" />

and would result in the following failure:

XmlDiffers(
  "different attribute ordering",
  Seq("first", "second"),
  Seq("second", "first"),
  Seq("test")
)

IgnoreChildOrder

If enabled the ordering of child elements will be ignored. This is handled by re-ordering child nodes using an arbitrary sorting algorithm before comparing them.

Note: the first difference returned may be different if this option is enabled.

Example 1

This:

<example>
  <child-1/>
  <child-2/>
</example>

would be considered equal to:

<example>
  <child-2/>
  <child-1/>
</example>

Example 2

This:

<example>
  <child-1 attribute1="value-1" attribute2="value-2"/>
  <child-2 attribute="something"/>
</example>

would be considered equal to:

<example>
  <child-2 attribute="something"/>
  <child-1 attribute2="value-2" attribute1="value-1" />
</example>

(The ordering of nodes and attributes are both ignored)