panic: make it more user friendly

Implements -h / -help / --help / help

Had to update a lot of hardcoded offsets in expectations.

Author: maruel

cmd/panic/main.go

@@ -42,21 +42,14 @@ import (
 
 func main() {
 	if len(os.Args) == 2 {
-		n := os.Args[1]
-		if f, ok := types[n]; ok {
-			fmt.Printf("GOTRACEBACK=%s\n", os.Getenv("GOTRACEBACK"))
-			if n == "simple" {
-				// Since the map lookup creates another call stack entry, add a one-off
-				// "simple" panic style to test the very minimal case.
-				// types["simple"].f is never called.
-				panic("simple")
-			}
-			f.f()
-			os.Exit(3)
-		}
-		// Undocumented command to do a raw dump of the supported commands. This is
-		// used by unit tests in ../../stack.
-		if n == "dump_commands" {
+		switch n := os.Args[1]; n {
+		case "-h", "-help", "--help", "help":
+			usage()
+			os.Exit(0)
+
+		case "dump_commands":
+			// Undocumented command to do a raw dump of the supported commands. This
+			// is used by unit tests in ../../stack.
 			items := make([]string, 0, len(types))
 			for n := range types {
 				items = append(items, n)
@@ -66,11 +59,25 @@ func main() {
 				fmt.Printf("%s\n", n)
 			}
 			os.Exit(0)
+
+		default:
+			if f, ok := types[n]; ok {
+				fmt.Printf("GOTRACEBACK=%s\n", os.Getenv("GOTRACEBACK"))
+				if n == "simple" {
+					// Since the map lookup creates another call stack entry, add a
+					// one-off "simple" panic style to test the very minimal case.
+					// types["simple"].f is never called.
+					panic("simple")
+				}
+				f.f()
+				os.Exit(3)
+			}
+			fmt.Fprintf(stdErr, "unknown panic style %q\n", n)
+			os.Exit(1)
 		}
-		fmt.Fprintf(stdErr, "unknown panic style %q\n", n)
-		os.Exit(1)
 	}
 	usage()
+	os.Exit(1)
 }
 
 // Mocked in test.
@@ -426,7 +433,6 @@ Select the way to panic:
 	for _, n := range names {
 		fmt.Fprintf(stdErr, "- %-*s  %s\n", m, n, types[n].desc)
 	}
-	os.Exit(2)
 }
 
 //

internal/main_test.go

@@ -41,22 +41,22 @@ func TestProcess(t *testing.T) {
 			palette: testPalette,
 			simil:   stack.AnyPointer,
 			path:    basePath,
-			want:    "GOTRACEBACK=all\npanic: simple\n\nC1: runningA\n    Emain Fmain.go:52 ImainL()A\n",
+			want:    "GOTRACEBACK=all\npanic: simple\n\nC1: runningA\n    Emain Fmain.go:70 ImainL()A\n",
 		},
 		{
 			name:    "FullPath",
 			palette: testPalette,
 			simil:   stack.AnyValue,
 			path:    fullPath,
 			// "/" is used even on Windows.
-			want: fmt.Sprintf("GOTRACEBACK=all\npanic: simple\n\nC1: runningA\n    Emain F%s:52 ImainL()A\n", strings.Replace(filepath.Join(filepath.Dir(d), "cmd", "panic", "main.go"), "\\", "/", -1)),
+			want: fmt.Sprintf("GOTRACEBACK=all\npanic: simple\n\nC1: runningA\n    Emain F%s:70 ImainL()A\n", strings.Replace(filepath.Join(filepath.Dir(d), "cmd", "panic", "main.go"), "\\", "/", -1)),
 		},
 		{
 			name:    "NoColor",
 			palette: &Palette{},
 			simil:   stack.AnyValue,
 			path:    basePath,
-			want:    "GOTRACEBACK=all\npanic: simple\n\n1: running\n    main main.go:52 main()\n",
+			want:    "GOTRACEBACK=all\npanic: simple\n\n1: running\n    main main.go:70 main()\n",
 		},
 		{
 			name:    "Match",
@@ -72,7 +72,7 @@ func TestProcess(t *testing.T) {
 			simil:   stack.AnyValue,
 			path:    basePath,
 			filter:  regexp.MustCompile(`notpresent`),
-			want:    "GOTRACEBACK=all\npanic: simple\n\nC1: runningA\n    Emain Fmain.go:52 ImainL()A\n",
+			want:    "GOTRACEBACK=all\npanic: simple\n\nC1: runningA\n    Emain Fmain.go:70 ImainL()A\n",
 		},
 	}
 	for i, line := range data {
@@ -106,14 +106,14 @@ func TestProcessTwoSnapshots(t *testing.T) {
 		"GOTRACEBACK=all\n" +
 		"panic: simple\n\n" +
 		"1: running\n" +
-		"    main main.go:52 main()\n" +
+		"    main main.go:70 main()\n" +
 		"Ye\n" +
 		"GOTRACEBACK=all\n" +
 		"panic: 42\n\n" +
 		"1: running\n" +
-		"    main main.go:82  panicint(0x2a)\n" +
-		"    main main.go:280 glob..func7()\n" +
-		"    main main.go:54  main()\n" +
+		"    main main.go:89  panicint(0x2a)\n" +
+		"    main main.go:287 glob..func7()\n" +
+		"    main main.go:72  main()\n" +
 		"Yo\n")
 	compareString(t, want, out.String())
 }

stack/context_test.go

@@ -1178,7 +1178,7 @@ func TestScanSnapshotSyntheticTwoSnapshots(t *testing.T) {
 							"main.main",
 							Args{},
 							pathJoin(ppDir, "main.go"),
-							52,
+							70,
 						),
 					},
 				},
@@ -1207,19 +1207,19 @@ func TestScanSnapshotSyntheticTwoSnapshots(t *testing.T) {
 							"main.panicint",
 							Args{Values: []Arg{{Value: 42}}},
 							pathJoin(ppDir, "main.go"),
-							82,
+							89,
 						),
 						newCallLocal(
 							"main.glob..func7",
 							Args{},
 							pathJoin(ppDir, "main.go"),
-							280,
+							287,
 						),
 						newCallLocal(
 							"main.main",
 							Args{},
 							pathJoin(ppDir, "main.go"),
-							54,
+							72,
 						),
 					},
 				},
@@ -1689,7 +1689,7 @@ func testPanicRace(t *testing.T, s *Snapshot, b *bytes.Buffer, ppDir string) {
 							"main.main",
 							Args{},
 							pathJoin(ppDir, "main.go"),
-							54,
+							72,
 						),
 					},
 				},
@@ -1725,7 +1725,7 @@ func testPanicRace(t *testing.T, s *Snapshot, b *bytes.Buffer, ppDir string) {
 							"main.main",
 							Args{},
 							pathJoin(ppDir, "main.go"),
-							54,
+							72,
 						),
 					},
 				},