Enable code coverage in Test-Module and document framework testing design

Author: MariusStorhaug

.github/workflows/Test-Module.yml

@@ -72,6 +72,9 @@ jobs:
           Version: ${{ fromJson(inputs.Settings).Version }}
           WorkingDirectory: ${{ fromJson(inputs.Settings).WorkingDirectory }}
           Settings: Module
+          CodeCoverage_Enabled: true
+          CodeCoverage_OutputFormat: JaCoCo
+          CodeCoverage_CoveragePercentTarget: 0
 
   Lint-Module:
     name: Lint-Module (${{ matrix.OSName }})

README.md

@@ -163,6 +163,15 @@ The [PSModule - SourceCode tests](./scripts/tests/SourceCode/PSModule/PSModule.T
   - [PSModule framework settings for style and standards for modules](https://github.com/PSModule/Test-PSModule?tab=readme-ov-file#module-tests)
   - [PSScriptAnalyzer rules](https://github.com/PSModule/Invoke-ScriptAnalyzer)
 - This produces a JSON-based report that is used by [Get-PesterTestResults](#get-test-results) evaluate the results of the tests.
+- **Code coverage for framework-generated code**: This step also collects code coverage. During the
+  [build step](#build-module), [Build-PSModule](https://github.com/PSModule/Build-PSModule) injects boilerplate code
+  into the compiled `.psm1` file — including the `$IsWindows` compatibility shim, type accelerator registration for
+  public classes and enums, and the `OnRemove` cleanup hook. Because this code is generated by the framework, module
+  authors have no way to test it themselves. The framework tests in
+  [Test-PSModule](https://github.com/PSModule/Test-PSModule) exercise these code paths so they are covered.
+  The coverage artifacts from this step are aggregated with coverage from
+  [Test-ModuleLocal](#test-module) in the [Get code coverage](#get-code-coverage) step, ensuring that
+  framework-generated lines no longer appear as uncovered in the module author's coverage report.
 
 ### Test module
 
@@ -299,6 +308,9 @@ The [PSModule - Module tests](./scripts/tests/Module/PSModule/PSModule.Tests.ps1
 
 [workflow](./.github/workflows/Get-CodeCoverage.yml)
 - Gathers the code coverage from the previous steps and creates a summary of the results.
+- Coverage is aggregated from both the [Framework test](#framework-test) step (which covers framework-generated
+  boilerplate) and the [Test module](#test-module) step (which covers module author code). A command that is executed
+  in either step counts as covered. This ensures module authors are not penalized for lines they did not write.
 - If the code coverage is below the target, the workflow will fail here.
 
 ### Publish module