volumen/internal/markdown/golden_test.go

// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0

package markdown

import (
	"flag"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

var update = flag.Bool("update", false, "rewrite golden files")

// TestGoldenCorpus renders every corpus file and compares against the
// committed golden output. Run `go test ./internal/markdown -update` to
// regenerate after an intentional rendering change.
func TestGoldenCorpus(t *testing.T) {
	corpusDir := filepath.Join("testdata", "corpus")
	entries, err := os.ReadDir(corpusDir)
	if err != nil {
		t.Fatalf("read corpus: %v", err)
	}
	for _, entry := range entries {
		if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".md") {
			continue
		}
		name := strings.TrimSuffix(entry.Name(), ".md")
		t.Run(name, func(t *testing.T) {
			src, err := os.ReadFile(filepath.Join(corpusDir, entry.Name()))
			if err != nil {
				t.Fatalf("read corpus file: %v", err)
			}
			htmlOut, toc, err := RenderWithTOC(string(src))
			if err != nil {
				t.Fatalf("RenderWithTOC: %v", err)
			}
			got := "=== HTML ===\n" + htmlOut + "=== TOC ===\n" + toc
			goldenPath := filepath.Join("testdata", name+".html")
			if *update {
				if err := os.WriteFile(goldenPath, []byte(got), 0o644); err != nil {
					t.Fatalf("write golden: %v", err)
				}
				return
			}
			want, err := os.ReadFile(goldenPath)
			if err != nil {
				t.Fatalf("read golden (run with -update): %v", err)
			}
			if got != string(want) {
				t.Fatalf("output differs from golden:\n--- got ---\n%s\n--- want ---\n%s", got, want)
			}
		})
	}
}