fix: Remove custom -test flag that conflicted with driver's built-in flag (#4)

The custom `-test` flag for skipping test files conflicted with
singlechecker's built-in `-test` flag (registered by checker.RegisterFlags()).
This caused the flag to be silently ignored when running the linter directly.

The driver's built-in `-test` flag provides the same functionality,
so we remove the redundant custom implementation and delegate to it.

Changes:
- Remove `analyzeTests` variable and flag registration in `init()`
- Remove test file skipping logic from `buildSkipFiles()`
- Remove `TestFileFilterSkipTests` test and rename `TestFileFilterDefault` to `TestFileFilter`
- Remove `filefilterskip` testdata fixtures
- Update README to remove go vet usage and clarify -test flag is built-in
- Retract v0.1.0-v0.4.0 due to broken -test flag

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: mpyw

README.md

@@ -16,16 +16,6 @@ A Go linter that checks goroutine context propagation.
 
 ## Installation & Usage
 
-### Using [`go vet`](https://pkg.go.dev/cmd/go#hdr-Report_likely_mistakes_in_packages) (Recommended)
-
-```bash
-# Install the analyzer
-go install github.com/mpyw/goroutinectx/cmd/goroutinectx@latest
-
-# Run with go vet
-go vet -vettool=$(which goroutinectx) ./...
-```
-
 ### Using [`go tool`](https://pkg.go.dev/cmd/go#hdr-Run_specified_go_tool) (Go 1.24+)
 
 ```bash
@@ -267,12 +257,6 @@ This is useful for wrapper functions that abstract away goroutine spawning patte
 
 ## Flags
 
-> [!TIP]
-> When using `go vet -vettool`, pass flags directly:
-> ```bash
-> go vet -vettool=$(which goroutinectx) -goroutine-deriver='pkg.Func' ./...
-> ```
-
 ### `-goroutine-deriver`
 
 Require goroutines to call a specific function to derive context. Useful for APM libraries like New Relic.
@@ -368,16 +352,13 @@ Available flags:
 
 | Flag | Default | Description |
 |------|---------|-------------|
-| `-test` | `true` | Analyze test files (`*_test.go`) |
+| `-test` | `true` | Analyze test files (`*_test.go`) — built-in driver flag |
 
 Generated files (containing `// Code generated ... DO NOT EDIT.`) are always excluded and cannot be opted in.
 
 ```bash
 # Exclude test files from analysis
 goroutinectx -test=false ./...
-
-# With go vet
-go vet -vettool=$(which goroutinectx) -goroutinectx.test=false ./...
 ```
 
 ### `-spawnerlabel`

analyzer.go

@@ -39,9 +39,6 @@ var (
 	enableSpawner      bool
 	enableSpawnerlabel bool
 	enableGotask       bool
-
-	// File filtering flags.
-	analyzeTests bool
 )
 
 func init() {
@@ -59,9 +56,6 @@ func init() {
 	Analyzer.Flags.BoolVar(&enableSpawner, "spawner", true, "enable spawner checker")
 	Analyzer.Flags.BoolVar(&enableSpawnerlabel, "spawnerlabel", false, "enable spawnerlabel checker")
 	Analyzer.Flags.BoolVar(&enableGotask, "gotask", true, "enable gotask checker (requires -goroutine-deriver)")
-
-	// File filtering flags
-	Analyzer.Flags.BoolVar(&analyzeTests, "test", true, "analyze test files (*_test.go)")
 }
 
 // Analyzer is the main analyzer for goroutinectx.
@@ -111,9 +105,9 @@ func run(pass *analysis.Pass) (any, error) {
 	return nil, nil
 }
 
-// buildSkipFiles creates a set of filenames to skip based on flags.
+// buildSkipFiles creates a set of filenames to skip.
 // Generated files are always skipped.
-// Test files are skipped when analyzeTests is false.
+// Test files can be skipped via the driver's built-in -test flag.
 func buildSkipFiles(pass *analysis.Pass) map[string]bool {
 	skipFiles := make(map[string]bool)
 
@@ -123,12 +117,6 @@ func buildSkipFiles(pass *analysis.Pass) map[string]bool {
 		// Always skip generated files
 		if ast.IsGenerated(file) {
 			skipFiles[filename] = true
-			continue
-		}
-
-		// Skip test files if -test=false
-		if !analyzeTests && strings.HasSuffix(filename, "_test.go") {
-			skipFiles[filename] = true
 		}
 	}
 

analyzer_test.go

@@ -132,23 +132,8 @@ func TestGotask(t *testing.T) {
 	analysistest.Run(t, testdata, goroutinectx.Analyzer, "gotask")
 }
 
-func TestFileFilterDefault(t *testing.T) {
+func TestFileFilter(t *testing.T) {
 	testdata := analysistest.TestData()
-	// Default: -test=true, so test files are analyzed
+	// Tests that generated files are skipped
 	analysistest.Run(t, testdata, goroutinectx.Analyzer, "filefilter")
 }
-
-func TestFileFilterSkipTests(t *testing.T) {
-	testdata := analysistest.TestData()
-
-	// Set -test=false to skip test files
-	if err := goroutinectx.Analyzer.Flags.Set("test", "false"); err != nil {
-		t.Fatal(err)
-	}
-
-	defer func() {
-		_ = goroutinectx.Analyzer.Flags.Set("test", "true")
-	}()
-
-	analysistest.Run(t, testdata, goroutinectx.Analyzer, "filefilterskip")
-}

go.mod

@@ -2,9 +2,10 @@ module github.com/mpyw/goroutinectx
 
 go 1.24.0
 
-// Retract all previous versions due to a bug where -goroutine-deriver flag
-// incorrectly disabled the base goroutine checker instead of running both independently.
-retract [v0.1.0, v0.2.0]
+// Retract all previous versions due to:
+// - v0.1.0-v0.2.0: -goroutine-deriver flag incorrectly disabled the base goroutine checker
+// - v0.1.0-v0.4.0: -test flag conflicted with singlechecker's built-in flag
+retract [v0.1.0, v0.4.0]
 
 require golang.org/x/tools v0.40.0