feat: warn if loaded changelog is whitespace-only

internal/pipe/changelog/changelog.go

@@ -316,17 +316,25 @@ func newSCMChangeloger(ctx *context.Context) (changeloger, error) {
 
 func loadContent(ctx *context.Context, fileName, tmplName string) (string, error) {
 	if tmplName != "" {
-		log.Debugf("loading template %s", tmplName)
+		log.Debugf("loading template %q", tmplName)
 		content, err := loadFromFile(tmplName)
 		if err != nil {
 			return "", err
 		}
-		return tmpl.New(ctx).Apply(content)
+		content, err = tmpl.New(ctx).Apply(content)
+		if strings.TrimSpace(content) == "" && err == nil {
+			log.Warnf("loaded %q, but it evaluates to an empty string", tmplName)
+		}
+		return content, err
 	}
 
 	if fileName != "" {
-		log.Debugf("loading file %s", fileName)
-		return loadFromFile(fileName)
+		log.Debugf("loading file %q", fileName)
+		content, err := loadFromFile(fileName)
+		if strings.TrimSpace(content) == "" && err == nil {
+			log.Warnf("loaded %q, but it is empty", fileName)
+		}
+		return content, err
 	}
 
 	return "", nil

internal/pipe/changelog/changelog_test.go

@@ -25,6 +25,13 @@ func TestChangelogProvidedViaFlag(t *testing.T) {
 	require.Equal(t, "c0ff33 coffeee\n", ctx.ReleaseNotes)
 }
 
+func TestChangelogProvidedViaFlagIsAnWhitespaceOnlyFile(t *testing.T) {
+	ctx := context.New(config.Project{})
+	ctx.ReleaseNotesFile = "testdata/changes-empty.md"
+	require.NoError(t, Pipe{}.Run(ctx))
+	require.Equal(t, "\n", ctx.ReleaseNotes)
+}
+
 func TestTemplatedChangelogProvidedViaFlag(t *testing.T) {
 	ctx := context.New(config.Project{})
 	ctx.ReleaseNotesFile = "testdata/changes.md"
@@ -34,6 +41,14 @@ func TestTemplatedChangelogProvidedViaFlag(t *testing.T) {
 	require.Equal(t, "c0ff33 coffeee v0.0.1\n", ctx.ReleaseNotes)
 }
 
+func TestTemplatedChangelogProvidedViaFlagResultIsEmpty(t *testing.T) {
+	ctx := context.New(config.Project{})
+	ctx.ReleaseNotesTmpl = "testdata/changes-templated-empty.md"
+	ctx.Git.CurrentTag = "v0.0.1"
+	require.NoError(t, Pipe{}.Run(ctx))
+	require.Equal(t, "\n\n", ctx.ReleaseNotes)
+}
+
 func TestChangelogProvidedViaFlagDoesntExist(t *testing.T) {
 	ctx := context.New(config.Project{})
 	ctx.ReleaseNotesFile = "testdata/changes.nope"

internal/pipe/changelog/testdata/changes-empty.md

@@ -0,0 +1 @@
+

internal/pipe/changelog/testdata/changes-templated-empty.md

@@ -0,0 +1 @@
+{{ print "\n" }}