Modify --follow behavior by minimizing noisy output (#122)

CHANGELOG.md

@@ -7,6 +7,11 @@ adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+- Modify `--follow` behavior by minimizing noisy output. (#122)
+
+> [!TIP]
+> If you want the existing behavior, I added a `--follow-verbose` flag. But please do let me know if this affected you, as I plan to remove this before cutting a `v1.0.0`. Thank you!
+
 ## [v0.13.3]
 
 - General housekeeping and dependency updates.

Makefile

@@ -57,3 +57,7 @@ build:
 search-todo:
 	@echo "Searching for TODOs in Go files..."
 	@rg '// TODO\(mf\):' --glob '*.go' || echo "No TODOs found."
+
+.PHONY: clean
+clean:
+	@find . -type f -name '*.FAIL' -delete

internal/app/app.go

@@ -26,7 +26,9 @@ type Options struct {
 	SummaryTableOptions SummaryTableOptions
 
 	// FollowOutput will follow the raw output as go test is running.
-	FollowOutput bool
+	FollowOutput        bool
+	FollowOutputVerbose bool
+
 	// Progress will print a single summary line for each package once the package has completed.
 	// Useful for long running test suites. Maybe used with FollowOutput or on its own.
 	Progress bool
@@ -59,6 +61,7 @@ func Run(w io.Writer, option Options) (int, error) {
 	summary, err := parse.Process(
 		reader,
 		parse.WithFollowOutput(option.FollowOutput),
+		parse.WithFollowVersboseOutput(option.FollowOutputVerbose),
 		parse.WithWriter(w),
 		parse.WithProgress(option.Progress),
 	)

main.go

@@ -31,6 +31,8 @@ var (
 	sortPtr        = flag.String("sort", "name", "")
 	progressPtr    = flag.Bool("progress", false, "")
 	comparePtr     = flag.String("compare", "", "")
+	// Undocumented flags
+	followVerbosePtr = flag.Bool("follow-verbose", false, "")
 
 	// Legacy flags
 	noBordersPtr = flag.Bool("noborders", false, "")
@@ -117,9 +119,10 @@ func main() {
 		disableColor = true
 	}
 	options := app.Options{
-		DisableColor: disableColor,
-		FollowOutput: *followPtr,
-		FileName:     *fileNamePtr,
+		DisableColor:        disableColor,
+		FollowOutput:        *followPtr,
+		FollowOutputVerbose: *followVerbosePtr,
+		FileName:            *fileNamePtr,
 		TestTableOptions: app.TestTableOptions{
 			Pass: *passPtr,
 			Skip: *skipPtr,

parse/event.go

@@ -85,12 +85,43 @@ func (e *Event) DiscardEmptyTestOutput() bool {
 	return e.Action == ActionOutput && e.Test == ""
 }
 
+// Prefixes for the different types of test updates. See:
+//
+//	https://github.com/golang/go/blob/38cfb3be9d486833456276777155980d1ec0823e/src/cmd/internal/test2json/test2json.go#L160-L168
+const (
+	updatePrefixRun   = "=== RUN   "
+	updatePrefixPause = "=== PAUSE "
+	updatePrefixCont  = "=== CONT  "
+	updatePrefixName  = "=== NAME  "
+	updatePrefixPass  = "=== PASS  "
+	updatePrefixFail  = "=== FAIL  "
+	updatePrefixSkip  = "=== SKIP  "
+)
+
 var updates = []string{
-	"=== RUN   ",
-	"=== PAUSE ",
-	"=== CONT  ",
+	updatePrefixRun,
+	updatePrefixPause,
+	updatePrefixCont,
 }
 
+// Prefix for the different types of test results. See
+//
+// https://github.com/golang/go/blob/38cfb3be9d486833456276777155980d1ec0823e/src/cmd/internal/test2json/test2json.go#L170-L175
+const (
+	resultPrefixPass  = "--- PASS: "
+	resultPrefixFail  = "--- FAIL: "
+	resultPrefixSkip  = "--- SKIP: "
+	resultPrefixBench = "--- BENCH: "
+)
+
+// BigResult reports whether the test output is a big pass or big fail
+//
+// https://github.com/golang/go/blob/38cfb3be9d486833456276777155980d1ec0823e/src/cmd/internal/test2json/test2json.go#L146-L150
+const (
+	bigPass = "PASS"
+	bigFail = "FAIL"
+)
+
 // Let's try using the LastLine method to report the package result.
 // If there are issues with LastLine() we can switch to this method.
 //

parse/process.go

@@ -28,6 +28,36 @@ func Process(r io.Reader, optionsFunc ...OptionsFunc) (*GoTestSummary, error) {
 		Packages: make(map[string]*Package),
 	}
 
+	noisy := []string{
+		// 1. Filter out noisy output, such as === RUN, === PAUSE, etc.
+		updatePrefixRun,
+		updatePrefixPause,
+		updatePrefixCont,
+		updatePrefixPass,
+		updatePrefixSkip,
+		// 2. Filter out report output, such as --- PASS: and --- SKIP:
+		resultPrefixPass,
+		resultPrefixSkip,
+	}
+	isNoisy := func(e *Event) bool {
+		output := strings.TrimSpace(e.Output)
+		// If the event is a big pass or fail, we can safely discard it. These are typically the
+		// lines preceding the package summary line. For example:
+		//
+		//  PASS
+		//  ok      fmt 0.144s
+		if e.Test == "" && (output == bigPass || output == bigFail) {
+			return true
+		}
+		for _, prefix := range noisy {
+			if strings.HasPrefix(output, prefix) {
+				return true
+			}
+		}
+		return false
+
+	}
+
 	sc := bufio.NewScanner(r)
 	var started bool
 	var badLines int
@@ -70,7 +100,10 @@ func Process(r io.Reader, optionsFunc ...OptionsFunc) (*GoTestSummary, error) {
 
 		// Optionally, as test output is piped to us, we write the plain
 		// text Output as if go test was run without the -json flag.
-		if option.follow && option.w != nil {
+		if (option.follow || option.followVerbose) && option.w != nil {
+			if !option.followVerbose && isNoisy(e) {
+				continue
+			}
 			fmt.Fprint(option.w, e.Output)
 		}
 		// Progress is a special case of follow, where we only print the

parse/process_options.go

@@ -5,10 +5,11 @@ import (
 )
 
 type options struct {
-	w        io.Writer
-	follow   bool
-	debug    bool
-	progress bool
+	w             io.Writer
+	follow        bool
+	followVerbose bool
+	debug         bool
+	progress      bool
 }
 
 type OptionsFunc func(o *options)
@@ -17,6 +18,10 @@ func WithFollowOutput(b bool) OptionsFunc {
 	return func(o *options) { o.follow = b }
 }
 
+func WithFollowVersboseOutput(b bool) OptionsFunc {
+	return func(o *options) { o.followVerbose = b }
+}
+
 func WithWriter(w io.Writer) OptionsFunc {
 	return func(o *options) { o.w = w }
 }

tests/follow_test.go

@@ -15,51 +15,97 @@ import (
 func TestFollow(t *testing.T) {
 	t.Parallel()
 
-	base := filepath.Join("testdata", "follow")
+	t.Run("follow_verbose", func(t *testing.T) {
+		base := filepath.Join("testdata", "follow-verbose")
 
-	tt := []struct {
-		fileName string
-		err      error
-		exitCode int
-	}{
-		// race detected
-		{"test_01", nil, 1},
-		{"test_02", nil, 0},
-		{"test_03", nil, 0},
-		{"test_04", nil, 0},
-		{"test_05", parse.ErrNotParsable, 1},
-		// build failure in one package
-		{"test_06", nil, 2},
-	}
-	for _, tc := range tt {
-		t.Run(tc.fileName, func(t *testing.T) {
-			inputFile := filepath.Join(base, tc.fileName+".jsonl")
-			options := app.Options{
-				FileName:           inputFile,
-				FollowOutput:       true,
-				DisableTableOutput: true,
-			}
-			var buf bytes.Buffer
-			gotExitCode, err := app.Run(&buf, options)
-			if err != nil && !errors.Is(err, tc.err) {
-				t.Fatal(err)
-			}
-			check.Number(t, gotExitCode, tc.exitCode)
-			goldenFile := filepath.Join(base, tc.fileName+".golden")
-			want, err := os.ReadFile(goldenFile)
-			if err != nil {
-				t.Fatal(err)
-			}
-			if !bytes.Equal(buf.Bytes(), want) {
-				t.Error("input does not match expected output; diff files in follow dir suffixed with .FAIL to debug")
-				t.Logf("diff %v %v",
-					"tests/"+goldenFile+".FAIL",
-					"tests/"+inputFile+".FAIL",
-				)
-				if err := os.WriteFile(goldenFile+".FAIL", buf.Bytes(), 0644); err != nil {
+		tt := []struct {
+			fileName string
+			err      error
+			exitCode int
+		}{
+			// race detected
+			{"test_01", nil, 1},
+			{"test_02", nil, 0},
+			{"test_03", nil, 0},
+			{"test_04", nil, 0},
+			{"test_05", parse.ErrNotParsable, 1},
+			// build failure in one package
+			{"test_06", nil, 2},
+		}
+		for _, tc := range tt {
+			t.Run(tc.fileName, func(t *testing.T) {
+				inputFile := filepath.Join(base, tc.fileName+".jsonl")
+				options := app.Options{
+					FileName:            inputFile,
+					FollowOutput:        true,
+					FollowOutputVerbose: true,
+					DisableTableOutput:  true,
+				}
+				var buf bytes.Buffer
+				gotExitCode, err := app.Run(&buf, options)
+				if err != nil && !errors.Is(err, tc.err) {
+					t.Fatal(err)
+				}
+				check.Number(t, gotExitCode, tc.exitCode)
+				goldenFile := filepath.Join(base, tc.fileName+".golden")
+				want, err := os.ReadFile(goldenFile)
+				if err != nil {
 					t.Fatal(err)
 				}
-			}
-		})
+				checkGolden(t, inputFile, goldenFile, buf.Bytes(), want)
+			})
+		}
+	})
+
+	t.Run("follow_no_verbose", func(t *testing.T) {
+		base := filepath.Join("testdata", "follow")
+
+		tt := []struct {
+			fileName string
+			err      error
+			exitCode int
+		}{
+			{"test_01", nil, 0},
+		}
+		for _, tc := range tt {
+			t.Run(tc.fileName, func(t *testing.T) {
+				inputFile := filepath.Join(base, tc.fileName+".jsonl")
+				options := app.Options{
+					FileName:           inputFile,
+					FollowOutput:       true,
+					DisableTableOutput: true,
+				}
+				var buf bytes.Buffer
+				gotExitCode, err := app.Run(&buf, options)
+				if err != nil && !errors.Is(err, tc.err) {
+					t.Fatal(err)
+				}
+				check.Number(t, gotExitCode, tc.exitCode)
+				goldenFile := filepath.Join(base, tc.fileName+".golden")
+				want, err := os.ReadFile(goldenFile)
+				if err != nil {
+					t.Fatal(err)
+				}
+				checkGolden(t, inputFile, goldenFile, buf.Bytes(), want)
+			})
+		}
+	})
+}
+
+func checkGolden(
+	t *testing.T,
+	inputFile, goldenFile string,
+	got, want []byte,
+) {
+	t.Helper()
+	if !bytes.Equal(got, want) {
+		t.Error("input does not match expected output; diff files in follow dir suffixed with .FAIL to debug")
+		t.Logf("diff %v %v",
+			"tests/"+goldenFile+".FAIL",
+			"tests/"+inputFile+".FAIL",
+		)
+		if err := os.WriteFile(goldenFile+".FAIL", got, 0644); err != nil {
+			t.Fatal(err)
+		}
 	}
 }

tests/testdata/follow-verbose/test_01.golden

@@ -0,0 +1,39 @@
+=== RUN   TestRace
+==================
+WARNING: DATA RACE
+Write at 0x00c000090090 by goroutine 7:
+  debug/tparse-24.TestRace.func1()
+      /Users/michael.fridman/go/src/debug/tparse-24/some_test.go:7 +0x38
+
+Previous write at 0x00c000090090 by goroutine 6:
+  debug/tparse-24.TestRace()
+      /Users/michael.fridman/go/src/debug/tparse-24/some_test.go:8 +0x88
+  testing.tRunner()
+      /usr/local/go/src/testing/testing.go:827 +0x162
+
+Goroutine 7 (running) created at:
+  debug/tparse-24.TestRace()
+      /Users/michael.fridman/go/src/debug/tparse-24/some_test.go:7 +0x7a
+  testing.tRunner()
+      /usr/local/go/src/testing/testing.go:827 +0x162
+
+Goroutine 6 (running) created at:
+  testing.(*T).Run()
+      /usr/local/go/src/testing/testing.go:878 +0x650
+  testing.runTests.func1()
+      /usr/local/go/src/testing/testing.go:1119 +0xa8
+  testing.tRunner()
+      /usr/local/go/src/testing/testing.go:827 +0x162
+  testing.runTests()
+      /usr/local/go/src/testing/testing.go:1117 +0x4ee
+  testing.(*M).Run()
+      /usr/local/go/src/testing/testing.go:1034 +0x2ee
+  main.main()
+      _testmain.go:42 +0x221
+==================
+--- FAIL: TestRace (0.00s)
+    some_test.go:9: 64
+    testing.go:771: race detected during execution of test
+FAIL
+exit status 1
+FAIL	debug/tparse-24	0.020s