Centralize deterministic JSON file writing

internal/builtin/output.go

@@ -2,10 +2,9 @@ package builtin
 
 import (
 	"context"
-	"encoding/json"
-	"os"
 
 	"gitea.maximumdirect.net/eric/seriatim/internal/config"
+	"gitea.maximumdirect.net/eric/seriatim/internal/jsonfile"
 	"gitea.maximumdirect.net/eric/seriatim/internal/report"
 )
 
@@ -20,15 +19,7 @@ func (jsonOutputWriter) Write(ctx context.Context, out any, rpt report.Report, c
 		return nil, err
 	}
 
-	file, err := os.Create(cfg.OutputFile)
+	if err := jsonfile.Write(cfg.OutputFile, out); err != nil {
-	if err != nil {
-		return nil, err
-	}
-	defer file.Close()
-
-	enc := json.NewEncoder(file)
-	enc.SetIndent("", "  ")
-	if err := enc.Encode(out); err != nil {
 		return nil, err
 	}
 

internal/jsonfile/jsonfile.go

@@ -0,0 +1,28 @@
+package jsonfile
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+)
+
+// Write creates or truncates path and writes deterministic indented JSON.
+func Write(path string, value any) (err error) {
+	file, err := os.Create(path)
+	if err != nil {
+		return fmt.Errorf("create %q: %w", path, err)
+	}
+	defer func() {
+		closeErr := file.Close()
+		if err == nil && closeErr != nil {
+			err = fmt.Errorf("close %q: %w", path, closeErr)
+		}
+	}()
+
+	encoder := json.NewEncoder(file)
+	encoder.SetIndent("", "  ")
+	if err := encoder.Encode(value); err != nil {
+		return fmt.Errorf("encode %q: %w", path, err)
+	}
+	return nil
+}

internal/jsonfile/jsonfile_test.go

@@ -0,0 +1,69 @@
+package jsonfile
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestWriteFormatsWithTwoSpaceIndentAndTrailingNewline(t *testing.T) {
+	type payload struct {
+		Name  string `json:"name"`
+		Items []int  `json:"items"`
+	}
+
+	path := filepath.Join(t.TempDir(), "out.json")
+	value := payload{
+		Name:  "alpha",
+		Items: []int{1, 2},
+	}
+
+	if err := Write(path, value); err != nil {
+		t.Fatalf("write failed: %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read output: %v", err)
+	}
+
+	got := string(data)
+	want := "{\n  \"name\": \"alpha\",\n  \"items\": [\n    1,\n    2\n  ]\n}\n"
+	if got != want {
+		t.Fatalf("formatted JSON mismatch\nwant:\n%s\ngot:\n%s", want, got)
+	}
+}
+
+func TestWriteProducesValidJSON(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "out.json")
+
+	value := map[string]any{
+		"application": "seriatim",
+		"segments": []map[string]any{
+			{
+				"id":      1,
+				"speaker": "A",
+				"text":    "hello",
+			},
+		},
+	}
+
+	if err := Write(path, value); err != nil {
+		t.Fatalf("write failed: %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read output: %v", err)
+	}
+	if !strings.HasSuffix(string(data), "\n") {
+		t.Fatalf("output missing trailing newline: %q", string(data))
+	}
+
+	var decoded map[string]any
+	if err := json.Unmarshal(data, &decoded); err != nil {
+		t.Fatalf("output is not valid JSON: %v", err)
+	}
+}

internal/normalize/normalize.go

@@ -4,12 +4,12 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"os"
 	"strings"
 
 	"gitea.maximumdirect.net/eric/seriatim/internal/artifact"
 	"gitea.maximumdirect.net/eric/seriatim/internal/buildinfo"
 	"gitea.maximumdirect.net/eric/seriatim/internal/config"
+	"gitea.maximumdirect.net/eric/seriatim/internal/jsonfile"
 	"gitea.maximumdirect.net/eric/seriatim/internal/report"
 )
 
@@ -47,7 +47,7 @@ func Run(ctx context.Context, cfg config.NormalizeConfig) error {
 		return err
 	}
 
-	if err := writeOutputJSON(cfg.OutputFile, built.Output); err != nil {
+	if err := jsonfile.Write(cfg.OutputFile, built.Output); err != nil {
 		return err
 	}
 
@@ -118,18 +118,3 @@ func Run(ctx context.Context, cfg config.NormalizeConfig) error {
 
 	return nil
 }
-
-func writeOutputJSON(path string, value any) error {
-	file, err := os.Create(path)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-
-	encoder := json.NewEncoder(file)
-	encoder.SetIndent("", "  ")
-	if err := encoder.Encode(value); err != nil {
-		return fmt.Errorf("encode normalize output JSON: %w", err)
-	}
-	return nil
-}

internal/report/report.go

@@ -1,9 +1,6 @@
 package report
 
-import (
+import "gitea.maximumdirect.net/eric/seriatim/internal/jsonfile"
-	"encoding/json"
-	"os"
-)
 
 // Severity classifies report events.
 type Severity string
@@ -62,13 +59,5 @@ func Warning(stage string, module string, message string) Event {
 
 // WriteJSON writes a deterministic JSON report.
 func WriteJSON(path string, rpt Report) error {
-	file, err := os.Create(path)
+	return jsonfile.Write(path, rpt)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-
-	enc := json.NewEncoder(file)
-	enc.SetIndent("", "  ")
-	return enc.Encode(rpt)
 }

internal/trim/run.go

@@ -8,6 +8,7 @@ import (
 	"sort"
 
 	"gitea.maximumdirect.net/eric/seriatim/internal/config"
+	"gitea.maximumdirect.net/eric/seriatim/internal/jsonfile"
 	"gitea.maximumdirect.net/eric/seriatim/internal/report"
 )
 
@@ -85,7 +86,7 @@ func Run(ctx context.Context, cfg config.TrimConfig) error {
 		return fmt.Errorf("validate trimmed output: %w", err)
 	}
 
-	if err := writeOutputJSON(cfg.OutputFile, outputArtifact.Value()); err != nil {
+	if err := jsonfile.Write(cfg.OutputFile, outputArtifact.Value()); err != nil {
 		return err
 	}
 
@@ -137,18 +138,6 @@ func Run(ctx context.Context, cfg config.TrimConfig) error {
 	return nil
 }
 
-func writeOutputJSON(path string, value any) error {
-	file, err := os.Create(path)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-
-	enc := json.NewEncoder(file)
-	enc.SetIndent("", "  ")
-	return enc.Encode(value)
-}
-
 func orderedIDMapping(mapping map[int]int) []idMapping {
 	keys := make([]int, 0, len(mapping))
 	for oldID := range mapping {