Add validation for PREVIOUS_RELEASE_TAG in release-notes-tool

When PREVIOUS_RELEASE_TAG is specified, validate that it:
- Uses proper ref format (e.g. tags/v1.0.0-rc.1)
- Contains alpha, beta, or rc pre-release identifier

Address review feedback:
- Reorder pre-release constants alphabetically (alpha, beta, rc)
- Update comments to reflect alphabetical ordering
- Remove commas from error message examples for consistency
- Update error messages to use alphabetical parameter order
- Simplify test error checking logic to be more concise

Fixes #12278

Author: tsuzu

hack/tools/release/notes/main.go

@@ -25,6 +25,7 @@ import (
 	"fmt"
 	"log"
 	"os/exec"
+	"strings"
 
 	"github.com/blang/semver/v4"
 	"github.com/pkg/errors"
@@ -42,6 +43,11 @@ const (
 	alphaRelease     = "ALPHA RELEASE"
 	betaRelease      = "BETA RELEASE"
 	releaseCandidate = "RELEASE CANDIDATE"
+
+	// Pre-release type constants.
+	preReleaseAlpha = "alpha"
+	preReleaseBeta  = "beta"
+	preReleaseRC    = "rc"
 )
 
 func main() {
@@ -140,15 +146,15 @@ func releaseTypeFromNewTag(newTagConfig string) string {
 		return ""
 	}
 
-	// Only allow RC and beta releases. More types must be defined here.
+	// Only allow alpha, beta and RC releases. More types must be defined here.
 	// If a new type is not defined, no warning banner will be printed.
 	switch newTag.Pre[0].VersionStr {
-	case "rc":
-		return releaseCandidate
-	case "beta":
-		return betaRelease
-	case "alpha":
+	case preReleaseAlpha:
 		return alphaRelease
+	case preReleaseBeta:
+		return betaRelease
+	case preReleaseRC:
+		return releaseCandidate
 	}
 	return ""
 }
@@ -187,6 +193,45 @@ func validateConfig(config *notesCmdConfig) error {
 		}
 	}
 
+	if config.previousReleaseVersion != "" {
+		if err := validatePreviousReleaseVersion(config.previousReleaseVersion); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func validatePreviousReleaseVersion(previousReleaseVersion string) error {
+	// Extract version string from ref format (e.g. "tags/v1.0.0-rc.1" -> "v1.0.0-rc.1")
+	if !strings.Contains(previousReleaseVersion, "/") {
+		return errors.New("--previous-release-version must be in ref format (e.g. tags/v1.0.0-rc.1)")
+	}
+
+	parts := strings.SplitN(previousReleaseVersion, "/", 2)
+	if len(parts) != 2 {
+		return errors.New("--previous-release-version must be in ref format (e.g. tags/v1.0.0-rc.1)")
+	}
+
+	versionStr := parts[1]
+
+	// Parse the version to check if it contains alpha, beta, or rc
+	version, err := semver.ParseTolerant(versionStr)
+	if err != nil {
+		return errors.Wrap(err, "invalid --previous-release-version, is not a valid semver")
+	}
+
+	// Check if the version has pre-release identifiers
+	if len(version.Pre) == 0 {
+		return errors.Errorf("--previous-release-version must contain '%s', '%s', or '%s' pre-release identifier", preReleaseAlpha, preReleaseBeta, preReleaseRC)
+	}
+
+	// Check if the first pre-release identifier is 'alpha', 'beta', or 'rc'
+	preReleaseType := version.Pre[0].VersionStr
+	if preReleaseType != preReleaseAlpha && preReleaseType != preReleaseBeta && preReleaseType != preReleaseRC {
+		return errors.Errorf("--previous-release-version must contain '%s', '%s', or '%s' pre-release identifier", preReleaseAlpha, preReleaseBeta, preReleaseRC)
+	}
+
 	return nil
 }
 

hack/tools/release/notes/main_test.go

@@ -20,6 +20,7 @@ limitations under the License.
 package main
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/blang/semver/v4"
@@ -229,12 +230,76 @@ func Test_validateConfig(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			name: "Invalid previousReleaseVersion without ref format",
+			args: &notesCmdConfig{
+				fromRef:                "ref1/tags",
+				toRef:                  "ref2/tags",
+				newTag:                 "v1.0.0",
+				previousReleaseVersion: "v1.0.0-rc.0",
+			},
+			wantErr:      true,
+			errorMessage: "--previous-release-version must be in ref format",
+		},
+		{
+			name: "Valid previousReleaseVersion with rc in ref format",
+			args: &notesCmdConfig{
+				fromRef:                "ref1/tags",
+				toRef:                  "ref2/tags",
+				newTag:                 "v1.0.0",
+				previousReleaseVersion: "tags/v1.0.0-rc.0",
+			},
+			wantErr: false,
+		},
+		{
+			name: "Valid previousReleaseVersion with alpha in ref format",
+			args: &notesCmdConfig{
+				fromRef:                "ref1/tags",
+				toRef:                  "ref2/tags",
+				newTag:                 "v1.0.0",
+				previousReleaseVersion: "tags/v1.0.0-alpha.1",
+			},
+			wantErr: false,
+		},
+		{
+			name: "Invalid previousReleaseVersion without pre-release in ref format",
+			args: &notesCmdConfig{
+				fromRef:                "ref1/tags",
+				toRef:                  "ref2/tags",
+				newTag:                 "v1.0.0",
+				previousReleaseVersion: "tags/v1.0.0",
+			},
+			wantErr:      true,
+			errorMessage: "--previous-release-version must contain 'alpha', 'beta', or 'rc' pre-release identifier",
+		},
+		{
+			name: "Invalid previousReleaseVersion with unsupported pre-release type",
+			args: &notesCmdConfig{
+				fromRef:                "ref1/tags",
+				toRef:                  "ref2/tags",
+				newTag:                 "v1.0.0",
+				previousReleaseVersion: "tags/v1.0.0-dev.1",
+			},
+			wantErr:      true,
+			errorMessage: "--previous-release-version must contain 'alpha', 'beta', or 'rc' pre-release identifier",
+		},
+		{
+			name: "Invalid previousReleaseVersion with invalid semver",
+			args: &notesCmdConfig{
+				fromRef:                "ref1/tags",
+				toRef:                  "ref2/tags",
+				newTag:                 "v1.0.0",
+				previousReleaseVersion: "tags/invalid-version",
+			},
+			wantErr:      true,
+			errorMessage: "invalid --previous-release-version, is not a valid semver",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			err := validateConfig(tt.args)
 			if tt.wantErr {
-				if err == nil || err.Error() != tt.errorMessage {
+				if err == nil || !strings.Contains(err.Error(), tt.errorMessage) {
 					t.Errorf("expected error '%s', got '%v'", tt.errorMessage, err)
 				}
 			} else if err != nil {