Migrate integration tests to NIO2 Path API

[gnodet]

Summary

Migrate Maven Integration Tests from java.io.File to NIO2 java.nio.file.Path API, making Path-based methods the primary API while maintaining familiar method names.

Changes Made

Infrastructure Migration

1. Migrated Verifier class to NIO2:

   • Added Path-based overloads for loadProperties(), loadFile(), filterFile()
   • Replaced FileUtils operations with native NIO2 methods (Files.walk(), Files.copy(), etc.)
   • Implemented custom deleteDirectoryRecursively() using Files.walk()
   • Updated file verification methods to use Path and DirectoryStream
   • Removed dependency on org.codehaus.plexus.util.FileUtils
   • Fixed wildcard path handling on Windows
   • Added InvalidPathException fallback to File API for paths NIO2 rejects (e.g., trailing spaces on Windows)

2. Migrated AbstractMavenIntegrationTestCase class:

   • Changed extractResources() to return Path instead of File
   • Strips leading / from resource paths — Path.resolve("/child") replaces the base entirely (unlike new File(parent, "/child") which silently strips it)
   • Updated settings file handling to use Path operations
   • Removed unused File imports

3. Centralized FileUtils usage into ItUtils:

   • copyDirectoryStructure(), deleteDirectory(), createFile(), lastModified(), canonicalPath()
   • Uses FileUtils.copyDirectoryStructure (preserves hierarchy), Files.createFile, Files.getLastModifiedTime with existence check, Files.deleteIfExists

4. Updated HttpServer with source(Path) overload for file-based serving

5. Made Path-based methods the primary API:

   • extractResources() now returns Path (was File)
   • All filterFile() methods now return Path (were File)
   • Removed all File-based wrapper methods

Integration Tests Migration

• Migrated 735+ integration test files to use the new Path-based API
• All tests updated to use extractResources() returning Path
• Updated variable declarations from File to Path
• Converted new File(dir, subpath) patterns to dir.resolve(subpath)
• Updated .getAbsolutePath() calls to .toString() for Path variables
• Replaced FileReader with Files.newBufferedReader
• Files.deleteIfExists() where old File.delete() was lenient about missing files
• Platform-specific fixes:
  • Windows: Drive-relative paths require File.separator prefix after Path.subpath() (strips root entirely unlike File)
  • Unix: Skip drive-relative path manipulation — Path.subpath() creates plain relative paths resolved from CWD, not from filesystem root

Testing

• Added VerifierNIO2Test for new NIO2 functionality
• Added NIO2MigrationVerificationTest to verify common integration test patterns
• Added AbstractMavenIntegrationTestCaseNIO2Test
• Full CI green: all 18 jobs pass across Ubuntu, macOS, Windows × JDK 17, 21, 25

API Changes

Before (File-based)

protected File extractResources(String resourcePath) throws IOException
public File filterFile(String srcPath, String dstPath) throws IOException

After (Path-based)

protected Path extractResources(String resourcePath) throws IOException
public Path filterFile(String srcPath, String dstPath) throws IOException

Migration Statistics

• Infrastructure files migrated: 4 core classes (Verifier, AbstractMavenIntegrationTestCase, ItUtils, HttpServer)
• Integration test files migrated: 735+ files
• Total files changed: 749
• Lines changed: ~4,400 insertions / ~4,200 deletions

Key NIO2 Behavioral Differences Addressed

java.io.File	java.nio.file.Path	Fix
new File(parent, "/child") strips leading /	Path.resolve("/child") replaces base entirely	Strip leading / in extractResources()
file.lastModified() returns 0L for missing files	Files.getLastModifiedTime() throws NoSuchFileException	Existence check returning 0L
file.delete() returns false for missing files	Files.delete() throws NoSuchFileException	Use Files.deleteIfExists()
new File(path) accepts any string	Paths.get(path) validates (rejects trailing spaces on Windows)	Catch InvalidPathException, fall back to File API
Drive-relative paths implicit on Windows	Path.subpath() strips root entirely	Prepend File.separator on Windows