Excavator: Migrate Groovy nebula test PalantirJavaFormatPluginTest to the new Java Junit framework

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Changes produced by the roomba/migrate-gradle-testing-junit-framework check.

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Claude Execution Message

Claude finished running successfully.

Perfect! Let me create a summary of what was accomplished:

Migration Complete!

I've successfully migrated the PalantirJavaFormatPluginTest from the Nebula/Spock testing framework to the new Java-based testing framework. Here's what was done:

Key Changes:

1. Framework Migration:

   • Changed from Groovy/Spock to Java/JUnit 5
   • Replaced IntegrationTestKitSpec base class with @GradlePluginTests annotation
   • Converted Spock's @Unroll parameterized test to JUnit 5's @ParameterizedTest with @CsvSource

2. Test Structure:

   • Test name changed from 'formatDiff updates only lines changed in git diff' to formatDiff_updates_only_lines_changed_in_git_diff (snake_case)
   • Used parameter injection for GradleInvoker and RootProject
   • Added delineator comments to both original and new test files for easier review

3. File Operations:

   • Replaced buildFile << with project.buildGradle().append()
   • Replaced file('gradle.properties') << with project.gradlePropertiesFile().append()
   • Used project.mainSourceSet().java().writeClass() for creating Java files
   • Used structured .plugins().add() API instead of inline plugin declarations

4. Assertions:

   • Replaced Spock's implicit assertions with explicit AssertJ assertions
   • Used fluent assertion API: assertThat(result).output().contains()
   • Used file-specific assertions: file.assertThat().content().isEqualTo()

5. Error Handling:

   • Fixed Error Prone GradleTestStringFormatting issues by using varargs overload
   • Fixed Error Prone GradleTestPluginsBlock issues by using .plugins().add() API
   • Cleaned up unused code and imports

Files Modified:

• ✅ Original Groovy test: Added delineator comments at /repo/gradle-palantir-java-format/src/test/groovy/com/palantir/javaformat/gradle/PalantirJavaFormatPluginTest.groovy
• ✅ New Java test: Created at /repo/gradle-palantir-java-format/src/test/java/com/palantir/javaformat/gradle/PalantirJavaFormatPluginTest.java
• ✅ Migration errors documented at /repo/test-migration-errors.md

Verification:

• ✅ Test compiles successfully with no errors
• ✅ All Error Prone checks pass
• ✅ Follows all testing-guide.md best practices

The migrated test maintains all the original functionality while leveraging the modern, type-safe Java testing framework with better IDE support and cleaner syntax.

Claude Code Metrics

Metric	Value
Total cost	$0.75095955
Total Duration (API)	97
Total Duration (WALL)	12446
Token usage	274250 (input), 333369 (output)

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Migration Notes

Test Migration Errors and Fixes

Initial Migration Issues

Issue 1: Incorrect assertThat usage for file content

Error: no suitable method found for assertThat(JavaFile)

Problem: Used the static assertThat() from GradlePluginTestAssertions on a JavaFile object.

Fix: Used the instance method file.assertThat() instead of the static method. The correct pattern is:

project.mainSourceSet()
    .java()
    .fileByClassName("Main")
    .assertThat()
    .content()
    .isEqualTo(expectedMainJava);

Learning: File objects have their own assertThat() method that returns appropriate AssertJ assertions. Only use the static assertThat() from GradlePluginTestAssertions for InvocationResult and TaskOutcome.

Issue 2: Error Prone GradleTestStringFormatting check failure

Error: Error Prone NullPointerException in GradleTestStringFormatting check when using append(extraGradleProperties) with a parameter variable.

Problem: The Error Prone check expects formatted strings to use the varargs overload for better IDE syntax highlighting.

Fix: Changed from:

project.gradlePropertiesFile().append(extraGradleProperties);

to:

project.gradlePropertiesFile().append("%s", extraGradleProperties);

Learning: Always use the varargs overload append(String format, Object... args) instead of append(String) when working with dynamic content. This provides better IDE syntax highlighting support.

Issue 3: Error Prone GradleTestStringFormatting check with .formatted()

Error: Use the varargs overload of methods to get syntax highlighting, rather than manually formatting strings with .formatted() or String.format()

Problem: Used .formatted() on a text block:

project.buildGradle().append("""
    dependencies {
        ...
    }
    """.formatted(CLASSPATH_FILE, extraDependencies));

Fix: Used the varargs overload instead:

project.buildGradle().append("""
    dependencies {
        ...
    }
    """, CLASSPATH_FILE, extraDependencies);

Learning: Never use .formatted() or String.format() when calling framework methods. Always use the varargs overload directly.

Issue 4: Error Prone GradleTestPluginsBlock check failure

Error: Plugins must be added using .plugins().add() method. Use gradleFile.plugins().add("plugin-id") instead.

Problem: Used apply plugin: 'idea' inside an append() call.

Fix: Changed to use the structured .plugins().add() API:

project.buildGradle().plugins().add("java").add("com.palantir.java-format").add("idea");

Learning: Always use the .plugins().add() API for adding plugins, never use apply plugin: syntax in append calls. The structured API ensures correct positioning and prevents duplicates.

Review Pass Issues

Observation 1: Unused variable

Issue: The variable classpathFilesContent in standardBuildFile() is read but never used.

Fix: Removed the unused variable:

String classpathFilesContent = Files.readString(new File(CLASSPATH_FILE).toPath());

Learning: Clean up unused code during migration. Don't carry over unnecessary operations from the original test.

Observation 2: Using properties file API correctly

Current code: Using append() for gradle properties

Status: Correct usage. According to testing-guide.md, appendProperty(key, value) should be used for key-value pairs in properties files. However, in this test we're appending complete property strings (including newlines in the jvm args case), so append() is appropriate.

Observation 3: Text block formatting

Current code: Text blocks are used consistently with newlines after the opening delimiter.

Status: Good. Follows the instruction to "Add a new line after a text block for clarity reasons."

Observation 4: Git command execution

Current approach: Using ProcessBuilder directly in a helper method.

Status: Acceptable. The framework doesn't provide built-in git support, so this is the appropriate way to execute git commands for tests that need them.

Second Review Pass - Cleanup

Fix 1: Removed unused variable and import

Issue: The variable classpathFilesContent was declared and assigned but never used. Also the Files import was no longer needed.

Fix: Removed both:

• Removed String classpathFilesContent = Files.readString(new File(CLASSPATH_FILE).toPath());
• Removed import java.nio.file.Files;
• Removed the throws IOException from standardBuildFile() method signature since it was only needed for the removed Files.readString() call

Learning: Clean up unused code and imports during migration. Don't carry over unnecessary operations from exploratory coding or the original test.

Final Review Pass

Final Compilation Check

Status: ✅ Test compiles successfully with no errors or warnings from Error Prone checks.

Checklist Against Testing Guide

• ✅ Uses @GradlePluginTests annotation
• ✅ Uses parameter injection for GradleInvoker and RootProject
• ✅ Uses fluent APIs for file manipulation
• ✅ Uses structured .plugins().add() API for adding plugins
• ✅ Uses modern AssertJ assertions via assertThat()
• ✅ Text blocks used correctly with proper formatting
• ✅ Test name changed to snake_case: formatDiff_updates_only_lines_changed_in_git_diff
• ✅ Delineator comments preserved from original Groovy test
• ✅ Helper method standardBuildFile() returns GradleFile for fluent chaining
• ✅ Uses varargs overload for all string formatting operations
• ✅ No unused code or imports

Migration Summary

Successfully migrated PalantirJavaFormatPluginTest from Nebula/Spock framework to the new Java-based testing framework. The test:

• Converts Spock's parameterized test using @Unroll and where: clause to JUnit 5's @ParameterizedTest with @CsvSource
• Uses Java text blocks for better readability
• Leverages the new framework's fluent APIs for file operations
• Uses proper assertion patterns following the testing guide
• Maintains all original test behavior including git repository setup and file content verification

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