feat: format markdown in changelog entry

internal/changelog/changelog.go

@@ -5,8 +5,10 @@ import (
 	_ "embed"
 	"html/template"
 	"log"
+	"log/slog"
 
 	"github.com/apricote/releaser-pleaser/internal/commitparser"
+	"github.com/apricote/releaser-pleaser/internal/markdown"
 )
 
 var (
@@ -24,7 +26,7 @@ func init() {
 	}
 }
 
-func NewChangelogEntry(commits []commitparser.AnalyzedCommit, version, link, prefix, suffix string) (string, error) {
+func NewChangelogEntry(logger *slog.Logger, commits []commitparser.AnalyzedCommit, version, link, prefix, suffix string) (string, error) {
 	features := make([]commitparser.AnalyzedCommit, 0)
 	fixes := make([]commitparser.AnalyzedCommit, 0)
 
@@ -50,5 +52,11 @@ func NewChangelogEntry(commits []commitparser.AnalyzedCommit, version, link, pre
 		return "", err
 	}
 
-	return changelog.String(), nil
+	formatted, err := markdown.Format(changelog.String())
+	if err != nil {
+		logger.Warn("failed to format changelog entry, using unformatted", "error", err)
+		return changelog.String(), nil
+	}
+
+	return formatted, nil
 }

internal/changelog/changelog.md.tpl

@@ -19,4 +19,4 @@
 
 {{- if .Suffix }}
 {{ .Suffix }}
-{{ end -}}
+{{ end }}

internal/changelog/changelog_test.go

@@ -1,6 +1,7 @@
 package changelog
 
 import (
+	"log/slog"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -34,7 +35,7 @@ func Test_NewChangelogEntry(t *testing.T) {
 				version:         "1.0.0",
 				link:            "https://example.com/1.0.0",
 			},
-			want:    "## [1.0.0](https://example.com/1.0.0)",
+			want:    "## [1.0.0](https://example.com/1.0.0)\n",
 			wantErr: assert.NoError,
 		},
 		{
@@ -50,7 +51,7 @@ func Test_NewChangelogEntry(t *testing.T) {
 				version: "1.0.0",
 				link:    "https://example.com/1.0.0",
 			},
-			want:    "## [1.0.0](https://example.com/1.0.0)\n### Features\n\n- Foobar!\n",
+			want:    "## [1.0.0](https://example.com/1.0.0)\n\n### Features\n\n- Foobar!\n",
 			wantErr: assert.NoError,
 		},
 		{
@@ -66,7 +67,7 @@ func Test_NewChangelogEntry(t *testing.T) {
 				version: "1.0.0",
 				link:    "https://example.com/1.0.0",
 			},
-			want:    "## [1.0.0](https://example.com/1.0.0)\n### Bug Fixes\n\n- Foobar!\n",
+			want:    "## [1.0.0](https://example.com/1.0.0)\n\n### Bug Fixes\n\n- Foobar!\n",
 			wantErr: assert.NoError,
 		},
 		{
@@ -100,6 +101,7 @@ func Test_NewChangelogEntry(t *testing.T) {
 				link:    "https://example.com/1.0.0",
 			},
 			want: `## [1.0.0](https://example.com/1.0.0)
+
 ### Features
 
 - Blabla!
@@ -127,6 +129,7 @@ func Test_NewChangelogEntry(t *testing.T) {
 				prefix:  "### Breaking Changes",
 			},
 			want: `## [1.0.0](https://example.com/1.0.0)
+
 ### Breaking Changes
 
 ### Bug Fixes
@@ -150,6 +153,7 @@ func Test_NewChangelogEntry(t *testing.T) {
 				suffix:  "### Compatibility\n\nThis version is compatible with flux-compensator v2.2 - v2.9.",
 			},
 			want: `## [1.0.0](https://example.com/1.0.0)
+
 ### Bug Fixes
 
 - Foobar!
@@ -164,7 +168,7 @@ This version is compatible with flux-compensator v2.2 - v2.9.
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			got, err := NewChangelogEntry(tt.args.analyzedCommits, tt.args.version, tt.args.link, tt.args.prefix, tt.args.suffix)
+			got, err := NewChangelogEntry(slog.Default(), tt.args.analyzedCommits, tt.args.version, tt.args.link, tt.args.prefix, tt.args.suffix)
 			if !tt.wantErr(t, err) {
 				return
 			}

internal/markdown/goldmark.go

@@ -1,8 +1,12 @@
 package markdown
 
 import (
+	"bytes"
+
 	markdown "github.com/teekennedy/goldmark-markdown"
 	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/util"
 
 	"github.com/apricote/releaser-pleaser/internal/markdown/extensions"
 )
@@ -10,6 +14,23 @@ import (
 func New() goldmark.Markdown {
 	return goldmark.New(
 		goldmark.WithExtensions(extensions.Section),
+		goldmark.WithParserOptions(parser.WithASTTransformers(
+			util.Prioritized(&newLineTransformer{}, 1),
+		)),
 		goldmark.WithRenderer(markdown.NewRenderer()),
 	)
 }
+
+// Format the Markdown document in a style mimicking Prettier. This is done for compatibility with other tools
+// users might have installed in their IDE. This does not guarantee that the output matches Prettier exactly.
+func Format(input string) (string, error) {
+	var buf bytes.Buffer
+	buf.Grow(len(input))
+
+	err := New().Convert([]byte(input), &buf)
+	if err != nil {
+		return "", err
+	}
+
+	return buf.String(), nil
+}

internal/markdown/prettier.go

@@ -0,0 +1,31 @@
+package markdown
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+)
+
+type newLineTransformer struct{}
+
+var _ parser.ASTTransformer = (*newLineTransformer)(nil) // interface compliance
+
+func (t *newLineTransformer) Transform(doc *ast.Document, _ text.Reader, _ parser.Context) {
+	// No error can happen as they can only come from the walker function
+	_ = ast.Walk(doc, func(node ast.Node, entering bool) (ast.WalkStatus, error) {
+		if !entering || node.Type() != ast.TypeBlock {
+			return ast.WalkContinue, nil
+		}
+
+		switch node.Kind() {
+		case ast.KindListItem:
+			// Do not add empty lines between every list item
+			break
+		default:
+			// Add empty lines between every other block
+			node.SetBlankPreviousLines(true)
+		}
+
+		return ast.WalkContinue, nil
+	})
+}

releaserpleaser.go

@@ -239,7 +239,7 @@ func (rp *ReleaserPleaser) runReconcileReleasePR(ctx context.Context) error {
 		return err
 	}
 
-	changelogEntry, err := changelog.NewChangelogEntry(analyzedCommits, nextVersion, rp.forge.ReleaseURL(nextVersion), releaseOverrides.Prefix, releaseOverrides.Suffix)
+	changelogEntry, err := changelog.NewChangelogEntry(logger, analyzedCommits, nextVersion, rp.forge.ReleaseURL(nextVersion), releaseOverrides.Prefix, releaseOverrides.Suffix)
 	if err != nil {
 		return fmt.Errorf("failed to build changelog entry: %w", err)
 	}