This command line tool validates your XML files for proper formatting. If they are not formatted correctly, it prints the difference and returns with an error. You can use it two ways: 1) to fail your build if any X-like files (XML, XSD, XSL, XHTML) are not formatted correctly, and 2) to format them correctly.

Read this blog post of mine first: XCOP—XML Style Checker.

Install it first (read below if you can't install it):

$ gem install xcop

Run it locally and read its output:

$ xcop --help

To validate formatting of your XML files just pass their names as arguments:

$ xcop file1.xml file2.xml

If your files are not formatted correctly and xcop complains, you can ask it to "beautify" them, using --fix option:

$ xcop --fix broken-file.xml

To fix all files in the directory you can do (won't work if your file names contain spaces):

$ xcop --fix $(find . -name '*.xml')

How to use in Rakefile?

This is what you need there:

require 'xcop/rake_task'
desc 'Run XCop on all XML/XSL files in all directories'
Xcop::RakeTask.new(:xcop) do |task|
  task.license = 'LICENSE.txt' # no license by default
  task.quiet = true # FALSE by default
  task.includes = ['**/*.xml', '**/*.xsl'] # xml|xsd|xhtml|xsl|html by default
  task.excludes = ['target/**/*'] # empty by default
end

How to use as GitHub action?

Create new workflow file in repository under .github/workflows/xcop.yml:

---
name: XCOP
"on":
  # run on push to master events
  push:
    branches:
      - master
  # run on pull requests to master
  pull_request:
    brranches:
      - master
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: g4s8/xcop-action@master

To customize license location or files pattern use action inputs license and files:

- uses: g4s8/xcop-action@master
  with:
    license: MY_LICENSE.txt
    files: "src/*.xml"

How to use in Maven pom.xml?

You can integrate it with the help of maven-antrun-plugin:

<project>
  [...]
  <build>
    [...]
    <plugins>
      [...]
      <plugin>
        <artifactId>maven-antrun-plugin</artifactId>
        <version>1.8</version>
        <executions>
          <execution>
            <phase>verify</phase>
            <configuration>
              <target>
                <apply executable="xcop" failonerror="true">
                  <arg value="--license"/>
                  <arg value="LICENSE.txt"/>
                  <fileset dir=".">
                    <include name="**/*.xml"/>
                    <include name="**/*.xsd"/>
                    <exclude name="target/**/*"/>
                    <exclude name=".idea/**/*"/>
                  </fileset>
                </apply>
              </target>
            </configuration>
            <goals>
              <goal>run</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

How to use in Ant project.xml?

Something like this should work:

<project>
  [...]
  <target name="xcop">
    <apply executable="xcop" failonerror="true">
      <arg value="--license"/>
      <arg value="LICENSE.txt"/>
      <fileset dir=".">
        <include name="**/*.xml"/>
        <include name="**/*.xsd"/>
        <exclude name="target/**/*"/>
        <exclude name=".idea/**/*"/>
      </fileset>
    </apply>
  </target>
</project>

How to contribute

Read these guidelines. Make sure you build is green before you contribute your pull request. You will need to have Ruby 2.3+ and Bundler installed. Then:

$ bundle update
$ bundle exec rake

If it's clean and you don't see any error messages, submit your pull request.