Add redacted effective rendering

internal/yaml/write_test.go

@@ -0,0 +1,59 @@
+package yaml
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/ConfigKit/internal/document"
+)
+
+func TestWriteUsesStableExplicitFormatting(t *testing.T) {
+	t.Parallel()
+	root := &document.Node{Kind: document.Mapping, Mapping: []document.Entry{
+		{Key: "empty_map", Value: &document.Node{Kind: document.Mapping, Mapping: []document.Entry{}}},
+		{Key: "empty_sequence", Value: &document.Node{Kind: document.Sequence, Sequence: []*document.Node{}}},
+		{Key: "number", Value: &document.Node{Kind: document.Number, Text: "1.25e+2"}},
+		{Key: "redacted", Value: &document.Node{Kind: document.String, Text: "[REDACTED]"}},
+		{Key: "sequence", Value: &document.Node{Kind: document.Sequence, Sequence: []*document.Node{
+			{Kind: document.String, Text: "first"},
+			{Kind: document.String, Text: "true"},
+		}}},
+		{Key: "nil_value", Value: &document.Node{Kind: document.Null}},
+	}}
+	var output bytes.Buffer
+	if err := Write(&output, root); err != nil {
+		t.Fatal(err)
+	}
+	want := "empty_map: {}\nempty_sequence: []\nnumber: 1.25e+2\nredacted: '[REDACTED]'\nsequence:\n  - first\n  - 'true'\nnil_value: null\n"
+	if output.String() != want {
+		t.Fatalf("output:\n%s\nwant:\n%s", output.String(), want)
+	}
+}
+
+func TestWritePropagatesWriterErrorsAndShortWrites(t *testing.T) {
+	t.Parallel()
+	root := &document.Node{Kind: document.Mapping, Mapping: []document.Entry{{Key: "value", Value: &document.Node{Kind: document.String, Text: "safe"}}}}
+	want := errors.New("write failed")
+	if err := Write(failingWriter{err: want}, root); !errors.Is(err, want) {
+		t.Fatalf("writer error = %v", err)
+	}
+	if err := Write(shortOutput{}, root); !errors.Is(err, io.ErrShortWrite) {
+		t.Fatalf("short writer error = %v", err)
+	}
+}
+
+type failingWriter struct {
+	err error
+}
+
+func (writer failingWriter) Write(data []byte) (int, error) {
+	return min(2, len(data)), writer.err
+}
+
+type shortOutput struct{}
+
+func (shortOutput) Write(data []byte) (int, error) {
+	return max(0, len(data)-1), nil
+}