Add Markdown index HTML output mode

internal/transform/markdown/markdown_test.go

@@ -40,6 +40,124 @@ func TestGenerateMarkdownSidecar(t *testing.T) {
 	}
 }
 
+func TestGenerateMarkdownIndexExplicitInput(t *testing.T) {
+	backend := fake.New()
+	sourceBundle := testutil.WriteFakeSourceBundle(t, backend, "", testutil.BundleOptions{
+		ID: "bundle",
+		Files: []testutil.SourceFile{
+			{Path: "report.md", Data: "# Report\n"},
+			{Path: "notes.md", Data: "# Notes\n"},
+		},
+	})
+
+	outputs, err := New().Generate(context.Background(), transform.Request{
+		SourceBackend: backend,
+		SourceBundle:  sourceBundle,
+		Markdown:      transform.MarkdownOptions{Mode: transform.MarkdownModeIndex, Input: "notes.md"},
+	})
+
+	if err != nil {
+		t.Fatalf("Generate() error = %v", err)
+	}
+	if got, want := len(outputs), 1; got != want {
+		t.Fatalf("output count = %d, want %d", got, want)
+	}
+	output := outputs[0]
+	if output.Path != "index.html" || output.SourcePath != "notes.md" || output.Transform != transform.MarkdownToHTML {
+		t.Fatalf("output metadata = %#v, want index from notes.md", output)
+	}
+	if !strings.Contains(string(output.Data), "<h1>Notes</h1>") {
+		t.Fatalf("html = %q, want notes content", output.Data)
+	}
+	if output.SHA256 != bundle.FileDigest(output.Data) || output.Size != int64(len(output.Data)) {
+		t.Fatalf("digest/size metadata = %s/%d", output.SHA256, output.Size)
+	}
+}
+
+func TestGenerateMarkdownIndexSelectsOnlyMarkdownFile(t *testing.T) {
+	backend, sourceBundle := markdownFixture(t, "# Title\n\nHello.\n")
+
+	outputs, err := New().Generate(context.Background(), transform.Request{
+		SourceBackend: backend,
+		SourceBundle:  sourceBundle,
+		Markdown:      transform.MarkdownOptions{Mode: transform.MarkdownModeIndex},
+	})
+
+	if err != nil {
+		t.Fatalf("Generate() error = %v", err)
+	}
+	if got, want := outputs[0].Path, "index.html"; got != want {
+		t.Fatalf("path = %q, want %q", got, want)
+	}
+	if got, want := outputs[0].SourcePath, "report.md"; got != want {
+		t.Fatalf("source path = %q, want %q", got, want)
+	}
+}
+
+func TestGenerateMarkdownIndexRejectsAmbiguousInput(t *testing.T) {
+	backend := fake.New()
+	sourceBundle := testutil.WriteFakeSourceBundle(t, backend, "", testutil.BundleOptions{
+		ID: "bundle",
+		Files: []testutil.SourceFile{
+			{Path: "report.md", Data: "# Report\n"},
+			{Path: "notes.md", Data: "# Notes\n"},
+		},
+	})
+
+	_, err := New().Generate(context.Background(), transform.Request{
+		SourceBackend: backend,
+		SourceBundle:  sourceBundle,
+		Markdown:      transform.MarkdownOptions{Mode: transform.MarkdownModeIndex},
+	})
+
+	if err == nil || !strings.Contains(err.Error(), "multiple markdown source files") {
+		t.Fatalf("Generate() error = %v, want ambiguous input error", err)
+	}
+}
+
+func TestGenerateMarkdownIndexRejectsMissingMarkdown(t *testing.T) {
+	backend := fake.New()
+	sourceBundle := testutil.WriteFakeSourceBundle(t, backend, "", testutil.BundleOptions{
+		ID:    "bundle",
+		Files: []testutil.SourceFile{{Path: "summary.txt", Data: "Summary\n"}},
+	})
+
+	_, err := New().Generate(context.Background(), transform.Request{
+		SourceBackend: backend,
+		SourceBundle:  sourceBundle,
+		Markdown:      transform.MarkdownOptions{Mode: transform.MarkdownModeIndex},
+	})
+
+	if err == nil || !strings.Contains(err.Error(), "requires one markdown source file") {
+		t.Fatalf("Generate() error = %v, want missing markdown error", err)
+	}
+}
+
+func TestGenerateMarkdownIndexRejectsInvalidExplicitInput(t *testing.T) {
+	backend, sourceBundle := markdownFixture(t, "# Title\n")
+	tests := []struct {
+		name      string
+		input     string
+		wantError string
+	}{
+		{name: "unsafe", input: "../report.md", wantError: "markdown input"},
+		{name: "not listed", input: "missing.md", wantError: "not listed"},
+		{name: "not markdown", input: "summary.txt", wantError: "must end in .md"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := New().Generate(context.Background(), transform.Request{
+				SourceBackend: backend,
+				SourceBundle:  sourceBundle,
+				Markdown:      transform.MarkdownOptions{Mode: transform.MarkdownModeIndex, Input: tt.input},
+			})
+			if err == nil || !strings.Contains(err.Error(), tt.wantError) {
+				t.Fatalf("Generate() error = %v, want substring %q", err, tt.wantError)
+			}
+		})
+	}
+}
+
 func TestGenerateIgnoresNonMarkdown(t *testing.T) {
 	backend := fake.New()
 	if _, err := backend.WriteFile(context.Background(), "summary.txt", []byte("Summary\n"), storage.WriteOptions{}); err != nil {