Invoke Pester

Richard Mpanga edited this page May 11, 2017 · 17 revisions

Executes all Pester tests found in *.Tests.ps1 files, and provides various options for producing test output or generating metrics during execution.

DESCRIPTION

Upon calling Invoke-Pester, all files that have a name containing .Tests. will have the tests defined in their Describe blocks executed. Invoke-Pester begins at the location of relative_path and runs recursively through each sub directory looking for *.Tests.* files for tests to run. If a TestName is provided, Invoke-Pester will only run tests that have a describe block with a matching name. By default, Invoke-Pester will end the test run with a simple report of the number of tests passed and failed output to the console.

One may want pester to "fail a build" in the event that any tests fail. To accomodate this, Invoke-Pester will return an exit code equal to the number of failed tests if the EnableExit switch is set. Invoke-Pester will also write a NUnit style log of test results if the -OutputFormat NUnitXml parameter is provided. In these cases, Invoke-Pester will write the result log to the path provided in the -OutputFile parameter.

PARAMETER

Script (Alias: Path, relative_path)

Specifies the test files that Pester runs. As an example, the Invoke-Pester -Script .\Util* command runs all *.Tests.ps1 files in subdirectories with names that begin with 'Util' and their subdirectories.

You can also use the Script parameter to pass parameter names and values to a script that contains Pester tests. The value of the Script parameter can be a string, a hash table, or a collection of hash tables and strings. Wildcard characters are supported. The Path key is then required. (for details on why to do this see issue 271).

A more detailed example can be found in the online help of help Invoke-Pester -examples (EXAMPLE 3):

C:\PS>Invoke-Pester -Script @{ Path = './tests/Utils*'; Parameters = @{ NamedParameter = 'Passed By Name' }; Arguments = @('Passed by position') }

Executes a test, but will run them with the equivalent of the following command line: & $testScriptPath -NamedParameter 'Passed By Name' 'Passed by position'

TestName (Alias: Name)

Informs Invoke-Pester to filter Describe blocks that match this name. This value may contain wildcards. Only Describes block that match the TestName will be included in the returned object. -PassThru switch must be enabled

EnableExit

Will cause Invoke-Pester to exit with a exit code equal to the number of failed tests once all tests have been run. Use this to "fail" a build when any tests fail.

Tag (Alias: Tags)

Another way of filtering the Describe blocks, this time based on the values that are passed to the Tag parameter of the Describe statement. This value may not contain wildcards. Only Describes block that match the Tag Name will be included in the returned object. -PassThru switch must be enabled

PassThru

Causes Invoke-Pester to produce an output object which can be analyzed by its caller, instead of only sending output to the console. This can be used as part of a Continuous Integration written in PowerShell, as opposed to relying on a program to read the NUnit xml files produced when the -OutputFormat parameter is used.

The object produced by Invoke-Pester when the PassThru switch is used contains the following properties:

  • Path: The path in which tests were found and run.
  • TagFilter: The value that was passed to the -Tag parameter, if present.
  • TestNameFilter: The value that was passed to the -TestName parameter, if present.
  • TotalCount: Number of tests executed.
  • PassedCount: Number of passed tests
  • FailedCount: Number of failed tests.
  • Time: Total time of test execution.
  • TestResult: An array of individual test results, which are themselves objects containing the name of the Describe, Context and It, a Passed flag indicating whether the test passed or failed, a Time value for this test, a FailureMessage (if the test failed), and a stack trace.
  • CodeCoverage: If the -CodeCoverage parameter was also passed to Invoke-Pester, the output object will contain a CodeCoverage property as well.

CodeCoverage

Causes Pester to produce a report of code coverage metrics while the tests are executing. For more details, refer to the Code Coverage section of this wiki.

Strict

Reduces the possible outcome of a test to Passed or Failed only. Any Pending or Skipped test will translate to Failed (see It). This is useful for running tests as a part of continuos integration, where you need to make sure that all tests passed, and no tests were skipped or pending.

OutputFile

The path where Invoke-Pester will save formatted test results log file. If this path is not provided, no log will be generated.

OutputFormat

The format of output. Two formats of output are supported: NUnitXML and LegacyNUnitXML.

OutputXml

The parameter OutputXml is deprecated, please use OutputFile and OutputFormat instead.

The path where Invoke-Pester will save a NUnit formatted test results log file. If this path is not provided, no log will be generated.

PesterOption

Sets advanced options for the test execution. Enter a PesterOption object, such as one that you create by using the New-PesterOption cmdlet, or a hash table in which the keys are option names and the values are option values.

For more information on the options available, see the help for New-PesterOption.

Example 1

Invoke-Pester

This will find all *.tests.* files and run their tests. No exit code will be returned and no log file will be saved.

Example 2

Invoke-Pester ./tests/Utils*

This will run all tests in files under ./Tests that begin with Utils and also contains .Tests.

Example 3

Invoke-Pester -TestName "Add Numbers"

This will only run the Describe block named "Add Numbers"

Example 4

Invoke-Pester -EnableExit -OutputFile "./artifacts/TestResults.xml" -OutputFormat NUnitXml

This runs all tests from the current directory downwards and writes the results according to the NUnit schema to artifatcs/TestResults.xml just below the current directory. The test run will return an exit code equal to the number of test failures.

Example 5

$result = Invoke-Pester -PassThru

This saves an object containing the results of the tests to the $result variable. This can be analyzed as part of a Continuous Integration solution developed in PowerShell.

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