feat: update changelog file

changelog_test.go

@@ -1,16 +1,108 @@
 package rp
 
 import (
+	"io"
+	"log"
 	"testing"
 
+	"github.com/go-git/go-git/v5"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/apricote/releaser-pleaser/internal/testutils"
 )
 
 func ptr[T any](input T) *T {
 	return &input
 }
 
-func Test_formatChangelog(t *testing.T) {
+func TestUpdateChangelogFile(t *testing.T) {
+	tests := []struct {
+		name            string
+		repoFn          testutils.Repo
+		entry           string
+		expectedContent string
+		newFile         bool
+		wantErr         assert.ErrorAssertionFunc
+	}{
+		{
+			name:            "empty repo",
+			repoFn:          testutils.WithTestRepo(),
+			entry:           "## v1.0.0\n",
+			expectedContent: "# Changelog\n\n## v1.0.0\n",
+			newFile:         true,
+			wantErr:         assert.NoError,
+		},
+		{
+			name: "repo with well-formatted changelog",
+			repoFn: testutils.WithTestRepo(testutils.WithCommit("feat: add changelog", testutils.WithFile(ChangelogFile, `# Changelog
+
+## v0.0.1
+
+- Bazzle
+
+## v0.1.0
+
+### Bazuuum
+`))),
+			entry: "## v1.0.0\n\n- Version 1, juhu.\n",
+			expectedContent: `# Changelog
+
+## v1.0.0
+
+- Version 1, juhu.
+
+## v0.0.1
+
+- Bazzle
+
+## v0.1.0
+
+### Bazuuum
+`,
+			wantErr: assert.NoError,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			repo := tt.repoFn(t)
+			wt, err := repo.Worktree()
+			require.NoError(t, err, "failed to get worktree")
+
+			err = UpdateChangelogFile(wt, tt.entry)
+			if !tt.wantErr(t, err) {
+				return
+			}
+
+			wtStatus, err := wt.Status()
+			require.NoError(t, err, "failed to get worktree status")
+
+			assert.Len(t, wtStatus, 1, "worktree status does not have the expected entry number")
+
+			changelogFileStatus := wtStatus.File(ChangelogFile)
+
+			if tt.newFile {
+				assert.Equal(t, git.Unmodified, changelogFileStatus.Worktree, "unexpected file status in worktree")
+				assert.Equal(t, git.Added, changelogFileStatus.Staging, "unexpected file status in staging")
+			} else {
+				assert.Equal(t, git.Modified, changelogFileStatus.Worktree, "unexpected file status in worktree")
+				assert.Equal(t, git.Modified, changelogFileStatus.Staging, "unexpected file status in staging")
+			}
+
+			changelogFile, err := wt.Filesystem.Open(ChangelogFile)
+			require.NoError(t, err)
+			defer changelogFile.Close()
+
+			changelogFileContent, err := io.ReadAll(changelogFile)
+			require.NoError(t, err)
+
+			assert.Equal(t, tt.expectedContent, string(changelogFileContent))
+		})
+	}
+}
+
+func Test_NewChangelogEntry(t *testing.T) {
 	type args struct {
 		commits []AnalyzedCommit
 		version string
@@ -111,7 +203,7 @@ func Test_formatChangelog(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			got, err := formatChangelog(tt.args.commits, tt.args.version, tt.args.link)
+			got, err := NewChangelogEntry(tt.args.commits, tt.args.version, tt.args.link)
 			if !tt.wantErr(t, err) {
 				return
 			}