diff --git a/attrs_test.go b/attrs_test.go new file mode 100644 index 0000000..3ee5bae --- /dev/null +++ b/attrs_test.go @@ -0,0 +1,905 @@ +package simplelog + +import ( + "bytes" + "context" + "encoding/json" + "errors" + "io" + "log/slog" + "net/http" + "net/http/httptest" + "os" + "reflect" + "strings" + "testing" + "time" +) + +// These tests assert on the bytes the handlers actually emit, because that is +// where the defect lives: the handlers accept attributes and then throw them +// away, so nothing short of reading the output proves they survived. + +// captureStdout redirects os.Stdout for the duration of fn and returns what was +// written to it. Both the console and the JSON handler write to os.Stdout, so +// this is the only way to see their real output. +func captureStdout(t *testing.T, fn func()) string { + t.Helper() + + r, w, err := os.Pipe() + if err != nil { + t.Fatalf("os.Pipe: %v", err) + } + + original := os.Stdout + os.Stdout = w + + collected := make(chan string, 1) + go func() { + var buf bytes.Buffer + _, _ = io.Copy(&buf, r) + collected <- buf.String() + }() + + defer func() { + os.Stdout = original + _ = r.Close() + }() + + fn() + + os.Stdout = original + if err := w.Close(); err != nil { + t.Fatalf("close pipe writer: %v", err) + } + + return <-collected +} + +// testRecord builds an INFO record carrying the given attributes. +func testRecord(message string, attrs ...slog.Attr) slog.Record { + record := slog.NewRecord(time.Now(), slog.LevelInfo, message, 0) + record.AddAttrs(attrs...) + return record +} + +// decodeLine parses a single line of JSON handler output. +func decodeLine(t *testing.T, output string) map[string]any { + t.Helper() + + line := strings.TrimSpace(output) + if line == "" { + t.Fatal("handler emitted no output") + } + + var decoded map[string]any + if err := json.Unmarshal([]byte(line), &decoded); err != nil { + t.Fatalf("output is not valid JSON: %v\noutput: %s", err, line) + } + return decoded +} + +// wantField asserts that a decoded JSON object has key with the given value. +func wantField(t *testing.T, decoded map[string]any, key string, want any) { + t.Helper() + + got, ok := decoded[key] + if !ok { + t.Fatalf("field %q missing from output: %v", key, decoded) + } + if got != want { + t.Fatalf("field %q = %v, want %v", key, got, want) + } +} + +// wantGroup asserts that a decoded JSON object has key holding a nested object. +func wantGroup(t *testing.T, decoded map[string]any, key string) map[string]any { + t.Helper() + + got, ok := decoded[key] + if !ok { + t.Fatalf("group %q missing from output: %v", key, decoded) + } + group, ok := got.(map[string]any) + if !ok { + t.Fatalf("field %q = %v, want a nested object", key, got) + } + return group +} + +// wantNoField asserts that a decoded JSON object does not carry key. +func wantNoField(t *testing.T, decoded map[string]any, key string) { + t.Helper() + + if got, present := decoded[key]; present { + t.Fatalf("field %q unexpectedly present as %v: %v", key, got, decoded) + } +} + +// wantUnchanged asserts that a value the caller still owns was not written to +// by the handler. Logging must read what it is handed, never modify it. +func wantUnchanged(t *testing.T, what string, got, want any) { + t.Helper() + + if !reflect.DeepEqual(got, want) { + t.Fatalf("handler mutated the caller's %s: got %v, want %v", what, got, want) + } +} + +// wantContains asserts that console output contains a fragment. +func wantContains(t *testing.T, output, fragment string) { + t.Helper() + + if !strings.Contains(output, fragment) { + t.Fatalf("output does not contain %q\noutput: %s", fragment, output) + } +} + +// wantNotContains asserts that console output does not contain a fragment. +func wantNotContains(t *testing.T, output, fragment string) { + t.Helper() + + if strings.Contains(output, fragment) { + t.Fatalf("output unexpectedly contains %q\noutput: %s", fragment, output) + } +} + +// castTarget is a slog.LogValuer: the handler must resolve it rather than +// serialising the struct itself. +type castTarget struct { + id string +} + +func (c castTarget) LogValue() slog.Value { + return slog.StringValue(c.id) +} + +var _ slog.LogValuer = castTarget{} + +func TestJSONHandlerEmitsRecordAttrs(t *testing.T) { + output := captureStdout(t, func() { + handler := NewJSONHandler() + record := testRecord( + "casting", + slog.String("device", "livingroom"), + slog.String("file", "movie.mp4"), + slog.Int("attempt", 3), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + decoded := decodeLine(t, output) + wantField(t, decoded, "Message", "casting") + wantField(t, decoded, "device", "livingroom") + wantField(t, decoded, "file", "movie.mp4") + wantField(t, decoded, "attempt", float64(3)) +} + +func TestJSONHandlerWithAttrsAccumulates(t *testing.T) { + output := captureStdout(t, func() { + handler := NewJSONHandler(). + WithAttrs([]slog.Attr{slog.String("service", "cattbox")}). + WithAttrs([]slog.Attr{slog.String("component", "caster")}) + record := testRecord("casting", slog.String("device", "livingroom")) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + decoded := decodeLine(t, output) + wantField(t, decoded, "service", "cattbox") + wantField(t, decoded, "component", "caster") + wantField(t, decoded, "device", "livingroom") +} + +func TestJSONHandlerWithAttrsDoesNotMutateReceiver(t *testing.T) { + parent := NewJSONHandler() + first := parent.WithAttrs([]slog.Attr{slog.String("worker", "first")}) + second := parent.WithAttrs([]slog.Attr{slog.String("worker", "second")}) + + firstOutput := captureStdout(t, func() { + if err := first.Handle(context.Background(), testRecord("work")); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + secondOutput := captureStdout(t, func() { + if err := second.Handle(context.Background(), testRecord("work")); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + parentOutput := captureStdout(t, func() { + if err := parent.Handle(context.Background(), testRecord("work")); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantField(t, decodeLine(t, firstOutput), "worker", "first") + wantField(t, decodeLine(t, secondOutput), "worker", "second") + + if _, present := decodeLine(t, parentOutput)["worker"]; present { + t.Fatalf("parent handler leaked an attribute from a derived handler: %s", parentOutput) + } +} + +func TestJSONHandlerWithGroupNestsAttrs(t *testing.T) { + output := captureStdout(t, func() { + handler := NewJSONHandler(). + WithGroup("cast"). + WithAttrs([]slog.Attr{slog.String("device", "livingroom")}) + record := testRecord("casting", slog.String("file", "movie.mp4")) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + decoded := decodeLine(t, output) + wantField(t, decoded, "Message", "casting") + + group := wantGroup(t, decoded, "cast") + wantField(t, group, "device", "livingroom") + wantField(t, group, "file", "movie.mp4") +} + +func TestJSONHandlerResolvesValues(t *testing.T) { + output := captureStdout(t, func() { + handler := NewJSONHandler() + record := testRecord( + "cast failed", + slog.Group("request", slog.Int("status", 502), slog.String("method", "POST")), + slog.Any("target", castTarget{id: "chromecast-7"}), + slog.Any("error", errors.New("connection refused")), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + decoded := decodeLine(t, output) + wantField(t, decoded, "target", "chromecast-7") + wantField(t, decoded, "error", "connection refused") + + group := wantGroup(t, decoded, "request") + wantField(t, group, "status", float64(502)) + wantField(t, group, "method", "POST") +} + +func TestConsoleHandlerEmitsRecordAttrs(t *testing.T) { + output := captureStdout(t, func() { + handler := NewConsoleHandler() + record := testRecord( + "casting", + slog.String("device", "livingroom"), + slog.String("file", "movie.mp4"), + slog.Int("attempt", 3), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, output, "casting") + wantContains(t, output, "device=livingroom") + wantContains(t, output, "file=movie.mp4") + wantContains(t, output, "attempt=3") +} + +func TestConsoleHandlerQuotesValuesNeedingIt(t *testing.T) { + output := captureStdout(t, func() { + handler := NewConsoleHandler() + record := testRecord("casting", slog.String("file", "The Movie.mp4")) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, output, `file="The Movie.mp4"`) +} + +// TestConsoleHandlerQuotesKeysNeedingIt pins the key side of the same rule. +// A key is quoted on the same terms as a value, and as one token including +// its group prefix, so that the "=" separating the pair is always the first +// one outside quotes. Every case here was compared against +// slog.NewTextHandler, which renders each of them identically. +func TestConsoleHandlerQuotesKeysNeedingIt(t *testing.T) { + tests := []struct { + name string + build func() slog.Handler + attrs []slog.Attr + want string + notWant string + }{ + { + name: "an ordinary key is left bare", + build: func() slog.Handler { return NewConsoleHandler() }, + attrs: []slog.Attr{slog.String("device", "livingroom")}, + want: " device=livingroom", + notWant: `"device"`, + }, + { + name: "a key containing an equals sign is quoted", + build: func() slog.Handler { return NewConsoleHandler() }, + attrs: []slog.Attr{slog.String("a=b", "v2")}, + want: ` "a=b"=v2`, + notWant: " a=b=v2", + }, + { + name: "a key containing a space is quoted", + build: func() slog.Handler { return NewConsoleHandler() }, + attrs: []slog.Attr{slog.String("my key", "v")}, + want: ` "my key"=v`, + notWant: " my key=v", + }, + { + name: "a key containing a quote is escaped", + build: func() slog.Handler { return NewConsoleHandler() }, + attrs: []slog.Attr{slog.String(`he"llo`, "v")}, + want: ` "he\"llo"=v`, + notWant: ` he"llo=v`, + }, + { + name: "a printable non-ascii key is left bare", + build: func() slog.Handler { return NewConsoleHandler() }, + attrs: []slog.Attr{slog.String("キー", "v")}, + want: " キー=v", + notWant: `"キー"`, + }, + { + name: "a group prefix is quoted together with its key", + build: func() slog.Handler { return NewConsoleHandler() }, + attrs: []slog.Attr{ + slog.Group("grp", slog.String("a=b", "v")), + }, + want: ` "grp.a=b"=v`, + notWant: " grp.a=b=v", + }, + { + name: "a WithGroup prefix needing quotes quotes the whole key", + build: func() slog.Handler { + return NewConsoleHandler().WithGroup("my grp") + }, + attrs: []slog.Attr{slog.String("k", "v")}, + want: ` "my grp.k"=v`, + notWant: " my grp.k=v", + }, + { + name: "an empty key is quoted rather than left as a gap", + build: func() slog.Handler { return NewConsoleHandler() }, + attrs: []slog.Attr{slog.String("", "v")}, + want: ` ""=v`, + notWant: " =v", + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + output := captureStdout(t, func() { + handler := test.build() + record := testRecord("casting", test.attrs...) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, output, test.want) + wantNotContains(t, output, test.notWant) + }) + } +} + +func TestConsoleHandlerWithAttrsAccumulates(t *testing.T) { + output := captureStdout(t, func() { + handler := NewConsoleHandler(). + WithAttrs([]slog.Attr{slog.String("service", "cattbox")}). + WithAttrs([]slog.Attr{slog.String("component", "caster")}) + record := testRecord("casting", slog.String("device", "livingroom")) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, output, "service=cattbox") + wantContains(t, output, "component=caster") + wantContains(t, output, "device=livingroom") +} + +func TestConsoleHandlerWithAttrsDoesNotMutateReceiver(t *testing.T) { + parent := NewConsoleHandler() + first := parent.WithAttrs([]slog.Attr{slog.String("worker", "first")}) + second := parent.WithAttrs([]slog.Attr{slog.String("worker", "second")}) + + firstOutput := captureStdout(t, func() { + if err := first.Handle(context.Background(), testRecord("work")); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + secondOutput := captureStdout(t, func() { + if err := second.Handle(context.Background(), testRecord("work")); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + parentOutput := captureStdout(t, func() { + if err := parent.Handle(context.Background(), testRecord("work")); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, firstOutput, "worker=first") + wantNotContains(t, firstOutput, "worker=second") + wantContains(t, secondOutput, "worker=second") + wantNotContains(t, secondOutput, "worker=first") + wantNotContains(t, parentOutput, "worker=") +} + +func TestConsoleHandlerWithGroupQualifiesAttrs(t *testing.T) { + output := captureStdout(t, func() { + handler := NewConsoleHandler(). + WithGroup("cast"). + WithAttrs([]slog.Attr{slog.String("device", "livingroom")}) + record := testRecord("casting", slog.String("file", "movie.mp4")) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, output, "cast.device=livingroom") + wantContains(t, output, "cast.file=movie.mp4") +} + +func TestConsoleHandlerResolvesValues(t *testing.T) { + output := captureStdout(t, func() { + handler := NewConsoleHandler() + record := testRecord( + "cast failed", + slog.Group("request", slog.Int("status", 502)), + slog.Any("target", castTarget{id: "chromecast-7"}), + slog.Any("error", errors.New("connection refused")), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, output, "request.status=502") + wantContains(t, output, "target=chromecast-7") + wantContains(t, output, `error="connection refused"`) +} + +func TestWebhookHandlerEmitsAttrs(t *testing.T) { + bodies := make(chan []byte, 1) + server := httptest.NewServer(http.HandlerFunc( + func(w http.ResponseWriter, r *http.Request) { + body, err := io.ReadAll(r.Body) + if err != nil { + t.Errorf("read webhook body: %v", err) + } + bodies <- body + w.WriteHeader(http.StatusOK) + }, + )) + defer server.Close() + + handler, err := NewWebhookHandler(server.URL) + if err != nil { + t.Fatalf("NewWebhookHandler: %v", err) + } + + withAttrs := handler.WithAttrs([]slog.Attr{slog.String("service", "cattbox")}) + record := testRecord("casting", slog.String("device", "livingroom")) + if err := withAttrs.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + + var body []byte + select { + case body = <-bodies: + case <-time.After(5 * time.Second): + t.Fatal("webhook handler posted nothing") + } + + decoded := decodeLine(t, string(body)) + wantField(t, decoded, "service", "cattbox") + wantField(t, decoded, "device", "livingroom") +} + +// TestMultiplexHandlerPassesAttrsThrough guards the composite handler that +// package init installs: attributes must survive the multiplex too. +func TestMultiplexHandlerPassesAttrsThrough(t *testing.T) { + output := captureStdout(t, func() { + handler := (&MultiplexHandler{handlers: []ExtendedHandler{NewJSONHandler()}}). + WithAttrs([]slog.Attr{slog.String("service", "cattbox")}) + record := testRecord("casting", slog.String("device", "livingroom")) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + decoded := decodeLine(t, output) + wantField(t, decoded, "service", "cattbox") + wantField(t, decoded, "device", "livingroom") +} + +// A logging library must read the values it is handed and never write to them. +// The dangerous shape is a group that shares a key with something the caller +// logged by reference: merging the group's members into whatever already sits +// at that key would reach straight back into the caller's own data structure. +// The next four tests hold every handler to that, through both the record path +// and the derived-logger path. + +func TestJSONHandlerDoesNotMutateCallerMap(t *testing.T) { + caller := map[string]any{"mine": "untouched"} + + output := captureStdout(t, func() { + handler := NewJSONHandler() + record := testRecord( + "casting", + slog.Any("g", caller), + slog.Group("g", slog.Int("injected", 1)), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantUnchanged(t, "map", caller, map[string]any{"mine": "untouched"}) + + // The later attribute wins the key outright, as any repeated key does. + group := wantGroup(t, decodeLine(t, output), "g") + wantField(t, group, "injected", float64(1)) + wantNoField(t, group, "mine") +} + +func TestJSONHandlerDoesNotMutateCallerMapThroughWithAttrs(t *testing.T) { + caller := map[string]any{"id": "req-1"} + + output := captureStdout(t, func() { + handler := NewJSONHandler(). + WithAttrs([]slog.Attr{slog.Any("req", caller)}). + WithGroup("req") + record := testRecord("cast failed", slog.Int("status", 502)) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantUnchanged(t, "map", caller, map[string]any{"id": "req-1"}) + + group := wantGroup(t, decodeLine(t, output), "req") + wantField(t, group, "status", float64(502)) + wantNoField(t, group, "id") +} + +// TestJSONHandlerDoesNotMutateCallerSlice is the slice form of the same +// hazard: a caller's slice is also handed over by reference, and appending +// into its spare capacity would be just as visible to the caller as writing +// into its map. The slice is built with room to spare so that an append within +// capacity cannot hide behind an unchanged length. +func TestJSONHandlerDoesNotMutateCallerSlice(t *testing.T) { + caller := make([]any, 2, 4) + caller[0] = "first" + caller[1] = "second" + + output := captureStdout(t, func() { + handler := NewJSONHandler() + record := testRecord( + "casting", + slog.Any("s", caller), + slog.Group("s", slog.Int("injected", 1)), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantUnchanged(t, "slice", caller, []any{"first", "second"}) + wantUnchanged( + t, + "slice backing array", + caller[:cap(caller)], + []any{"first", "second", nil, nil}, + ) + + group := wantGroup(t, decodeLine(t, output), "s") + wantField(t, group, "injected", float64(1)) +} + +func TestConsoleHandlerDoesNotMutateCallerMap(t *testing.T) { + caller := map[string]any{"mine": "untouched"} + + output := captureStdout(t, func() { + handler := NewConsoleHandler() + record := testRecord( + "casting", + slog.Any("g", caller), + slog.Group("g", slog.Int("injected", 1)), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantUnchanged(t, "map", caller, map[string]any{"mine": "untouched"}) + wantContains(t, output, "g.injected=1") +} + +func TestWebhookHandlerDoesNotMutateCallerMap(t *testing.T) { + caller := map[string]any{"id": "req-1"} + + bodies := make(chan []byte, 1) + server := httptest.NewServer(http.HandlerFunc( + func(w http.ResponseWriter, r *http.Request) { + body, err := io.ReadAll(r.Body) + if err != nil { + t.Errorf("read webhook body: %v", err) + } + bodies <- body + w.WriteHeader(http.StatusOK) + }, + )) + defer server.Close() + + handler, err := NewWebhookHandler(server.URL) + if err != nil { + t.Fatalf("NewWebhookHandler: %v", err) + } + + derived := handler. + WithAttrs([]slog.Attr{slog.Any("req", caller)}). + WithGroup("req") + record := testRecord("cast failed", slog.Int("status", 502)) + if err := derived.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + + var body []byte + select { + case body = <-bodies: + case <-time.After(5 * time.Second): + t.Fatal("webhook handler posted nothing") + } + + wantUnchanged(t, "map", caller, map[string]any{"id": "req-1"}) + + group := wantGroup(t, decodeLine(t, string(body)), "req") + wantField(t, group, "status", float64(502)) +} + +// TestJSONHandlerRendersDurationAsNanoseconds pins the json rendering of a +// duration to a number of nanoseconds, which is what slog.NewJSONHandler +// emits. A consumer that sums or compares the field needs a number; the "3s" +// form would silently arrive as a string. +func TestJSONHandlerRendersDurationAsNanoseconds(t *testing.T) { + output := captureStdout(t, func() { + handler := NewJSONHandler() + record := testRecord("casting", slog.Duration("elapsed", 3*time.Second)) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + decoded := decodeLine(t, output) + if _, isNumber := decoded["elapsed"].(float64); !isNumber { + t.Fatalf("field \"elapsed\" = %#v, want a json number", decoded["elapsed"]) + } + wantField(t, decoded, "elapsed", float64((3 * time.Second).Nanoseconds())) +} + +// TestConsoleHandlerRendersDurationReadably is the other half of that choice: +// the console line is read by a person, so it carries the same human-readable +// form slog.NewTextHandler uses. +func TestConsoleHandlerRendersDurationReadably(t *testing.T) { + output := captureStdout(t, func() { + handler := NewConsoleHandler() + record := testRecord("casting", slog.Duration("elapsed", 3*time.Second)) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, output, "elapsed=3s") +} + +// TestJSONHandlerContractEdgeCases pins the slog.Handler contract's four +// edge cases. Every case carries a control attribute as well, so a handler +// that emitted no attributes at all would fail rather than pass by omission. +// +// The empty group is attached through WithAttrs rather than to the record, +// because slog.Record.AddAttrs elides empty groups itself: routed through the +// record, the case would never reach the handler at all. +func TestJSONHandlerContractEdgeCases(t *testing.T) { + tests := []struct { + name string + build func() slog.Handler + attrs []slog.Attr + verify func(t *testing.T, decoded map[string]any) + }{ + { + name: "empty attr is ignored", + build: func() slog.Handler { return NewJSONHandler() }, + attrs: []slog.Attr{{}, slog.String("kept", "yes")}, + verify: func(t *testing.T, decoded map[string]any) { + wantField(t, decoded, "kept", "yes") + wantNoField(t, decoded, "") + }, + }, + { + name: "empty group is elided along with its key", + build: func() slog.Handler { + return NewJSONHandler(). + WithAttrs([]slog.Attr{slog.Group("empty")}) + }, + attrs: []slog.Attr{slog.String("kept", "yes")}, + verify: func(t *testing.T, decoded map[string]any) { + wantField(t, decoded, "kept", "yes") + wantNoField(t, decoded, "empty") + }, + }, + { + name: "group with an empty key is inlined", + build: func() slog.Handler { return NewJSONHandler() }, + attrs: []slog.Attr{ + slog.Group("", slog.String("inner", "yes")), + }, + verify: func(t *testing.T, decoded map[string]any) { + wantField(t, decoded, "inner", "yes") + wantNoField(t, decoded, "") + }, + }, + { + name: "WithGroup with an empty name is a no-op", + build: func() slog.Handler { + return NewJSONHandler().WithGroup("") + }, + attrs: []slog.Attr{slog.String("kept", "yes")}, + verify: func(t *testing.T, decoded map[string]any) { + wantField(t, decoded, "kept", "yes") + wantNoField(t, decoded, "") + }, + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + output := captureStdout(t, func() { + handler := test.build() + record := testRecord("casting", test.attrs...) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + test.verify(t, decodeLine(t, output)) + }) + } +} + +// TestConsoleHandlerContractEdgeCases holds the console handler to the same +// four rules, since it renders attributes through its own code path. +func TestConsoleHandlerContractEdgeCases(t *testing.T) { + tests := []struct { + name string + build func() slog.Handler + attrs []slog.Attr + want string + notWant string + }{ + { + name: "empty attr is ignored", + build: func() slog.Handler { return NewConsoleHandler() }, + attrs: []slog.Attr{{}, slog.String("kept", "yes")}, + want: "kept=yes", + notWant: " =", + }, + { + name: "empty group is elided along with its key", + build: func() slog.Handler { + return NewConsoleHandler(). + WithAttrs([]slog.Attr{slog.Group("empty")}) + }, + attrs: []slog.Attr{slog.String("kept", "yes")}, + want: "kept=yes", + notWant: "empty=", + }, + { + name: "group with an empty key is inlined", + build: func() slog.Handler { return NewConsoleHandler() }, + attrs: []slog.Attr{ + slog.Group("", slog.String("inner", "yes")), + }, + want: " inner=yes", + notWant: ".inner=", + }, + { + name: "WithGroup with an empty name is a no-op", + build: func() slog.Handler { + return NewConsoleHandler().WithGroup("") + }, + attrs: []slog.Attr{slog.String("kept", "yes")}, + want: " kept=yes", + notWant: ".kept=", + }, + } + + for _, test := range tests { + t.Run(test.name, func(t *testing.T) { + output := captureStdout(t, func() { + handler := test.build() + record := testRecord("casting", test.attrs...) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, output, test.want) + wantNotContains(t, output, test.notWant) + }) + } +} + +// TestJSONHandlerRecordFieldsWinKeyCollision pins a caller-visible surprise: +// the json payload is an object, so the record's own fields own their names +// and an attribute keyed after one of them is dropped rather than emitted. +func TestJSONHandlerRecordFieldsWinKeyCollision(t *testing.T) { + output := captureStdout(t, func() { + handler := NewJSONHandler() + record := testRecord( + "the real message", + slog.String("Time", "hijacked"), + slog.String("Level", "hijacked"), + slog.String("Message", "hijacked"), + slog.String("PC", "hijacked"), + slog.String("kept", "yes"), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + decoded := decodeLine(t, output) + wantField(t, decoded, "kept", "yes") + wantField(t, decoded, "Message", "the real message") + wantField(t, decoded, "Level", "INFO") + for _, reserved := range []string{"Time", "PC"} { + if decoded[reserved] == "hijacked" { + t.Fatalf("attribute overwrote the record's own %q field: %v", reserved, decoded) + } + } +} + +// TestJSONHandlerDuplicateKeysKeepLast pins the other consequence of the +// payload being an object: a key logged twice collapses to its last value. +func TestJSONHandlerDuplicateKeysKeepLast(t *testing.T) { + output := captureStdout(t, func() { + handler := NewJSONHandler() + record := testRecord( + "casting", + slog.String("device", "kitchen"), + slog.String("device", "livingroom"), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantField(t, decodeLine(t, output), "device", "livingroom") +} + +// TestConsoleHandlerKeepsDuplicateKeys is the console counterpart: a line of +// text is not an object, so both pairs survive there. +func TestConsoleHandlerKeepsDuplicateKeys(t *testing.T) { + output := captureStdout(t, func() { + handler := NewConsoleHandler() + record := testRecord( + "casting", + slog.String("device", "kitchen"), + slog.String("device", "livingroom"), + ) + if err := handler.Handle(context.Background(), record); err != nil { + t.Fatalf("Handle: %v", err) + } + }) + + wantContains(t, output, "device=kitchen") + wantContains(t, output, "device=livingroom") +}