chore(stage-release) allow selecting pre-release labels (#14070)

Implements the functionality to select a pre-release label (as discussed in: https://github.com/angular/material2/pull/13621#discussion_r225705238)

tools/release/prompt/new-version-prompt.ts

@@ -1,11 +1,13 @@
-import {ChoiceType, prompt, Separator} from 'inquirer';
+import {ChoiceType, prompt} from 'inquirer';
 import {createNewVersion, ReleaseType} from '../version-name/create-version';
 import {parseVersionName, Version} from '../version-name/parse-version';
+import {determineAllowedPrereleaseLabels} from './prerelease-labels';
 
 /** Answers that will be prompted for. */
 type VersionPromptAnswers = {
-  versionName: string;
-  manualCustomVersion: string;
+  proposedVersion: string;
+  isPrerelease: boolean;
+  prereleaseLabel: string;
 };
 
 /**
@@ -13,17 +15,25 @@ type VersionPromptAnswers = {
  * validated to be a proper increment of the specified current version.
  */
 export async function promptForNewVersion(currentVersion: Version): Promise<Version> {
-  const versionChoices: ChoiceType[] = [
-    new Separator(),
-    {value: 'custom-release', name: 'Release w/ custom version'}
-  ];
+  const allowedPrereleaseChoices = determineAllowedPrereleaseLabels(currentVersion);
+  const versionChoices: ChoiceType[] = [];
 
   if (currentVersion.prereleaseLabel) {
-    versionChoices.unshift(
-      createVersionChoice(currentVersion, 'pre-release', 'Pre-release'),
-      createVersionChoice(currentVersion, 'stable-release', 'Stable release'));
+    versionChoices.push(
+      createVersionChoice(currentVersion, 'stable-release', 'Stable release'),
+      createVersionChoice(currentVersion, 'bump-prerelease', 'Bump pre-release number'));
+
+    // Only add the option to change the prerelease label if the current version can be
+    // changed to a new label. e.g. a version that is already marked as release candidate
+    // shouldn't be changed to a beta or alpha version.
+    if (allowedPrereleaseChoices) {
+      versionChoices.push({
+        value: 'new-prerelease-label',
+        name: `New pre-release (${allowedPrereleaseChoices.map(c => c.value).join(', ')})`
+      });
+    }
   } else {
-    versionChoices.unshift(
+    versionChoices.push(
       createVersionChoice(currentVersion, 'major', 'Major release'),
       createVersionChoice(currentVersion, 'minor', 'Minor release'),
       createVersionChoice(currentVersion, 'patch', 'Patch release'));
@@ -31,19 +41,39 @@ export async function promptForNewVersion(currentVersion: Version): Promise<Vers
 
   const answers = await prompt<VersionPromptAnswers>([{
     type: 'list',
-    name: 'versionName',
+    name: 'proposedVersion',
     message: `What's the type of the new release?`,
     choices: versionChoices,
   }, {
-    type: 'input',
-    name: 'manualCustomVersion',
-    message: 'Please provide a custom release name:',
-    validate: enteredVersion =>
-      !!parseVersionName(enteredVersion) || 'This is not a valid Semver version',
-    when: ({versionName}) => versionName === 'custom-release'
+    type: 'prompt',
+    name: 'isPrerelease',
+    message: 'Should this be a pre-release?',
+    // Prompt whether this should a pre-release if the current release is not a pre-release
+    when: !currentVersion.prereleaseLabel,
+  }, {
+    type: 'list',
+    name: 'prereleaseLabel',
+    message: 'Please select a pre-release label:',
+    choices: allowedPrereleaseChoices,
+    when: ({isPrerelease, proposedVersion}) =>
+      // Only prompt for selecting a pre-release label if the current release is a pre-release,
+      // or the existing pre-release label should be changed.
+      isPrerelease || proposedVersion === 'new-prerelease-label',
   }]);
 
-  return parseVersionName(answers.manualCustomVersion || answers.versionName);
+  // In case the new version just changes the pre-release label, we base the new version
+  // on top of the current version. Otherwise, we use the proposed version from the
+  // prompt answers.
+  const newVersion = answers.proposedVersion === 'new-prerelease-label' ?
+      currentVersion.clone() :
+      parseVersionName(answers.proposedVersion);
+
+  if (answers.prereleaseLabel) {
+    newVersion.prereleaseLabel = answers.prereleaseLabel;
+    newVersion.prereleaseNumber = 0;
+  }
+
+  return newVersion;
 }
 
 /** Creates a new choice for selecting a version inside of an Inquirer list prompt. */

tools/release/prompt/prerelease-labels.ts

@@ -0,0 +1,28 @@
+import {Version} from '../version-name/parse-version';
+
+/** Inquirer choice for selecting an alpha pre-release label. */
+const ALPHA_CHOICE = {value: 'alpha', name: 'Alpha pre-release'};
+
+/** Inquirer choice for selecting an beta pre-release label. */
+const BETA_CHOICE = {value: 'beta', name: 'Beta pre-release'};
+
+/** Inquirer choice for selecting a release candidate label. */
+const RC_CHOICE = {value: 'rc', name: 'Release candidate'};
+
+/**
+ * Determines all allowed pre-release labels for a given version. For example, a
+ * release-candidate version cannot be changed to an alpha or beta pre-release.
+ */
+export function determineAllowedPrereleaseLabels(version: Version) {
+  const {prereleaseLabel} = version;
+
+  if (!prereleaseLabel) {
+    return [ALPHA_CHOICE, BETA_CHOICE, RC_CHOICE];
+  } else if (prereleaseLabel === 'alpha') {
+    return [BETA_CHOICE, RC_CHOICE];
+  } else if (prereleaseLabel === 'beta') {
+    return [RC_CHOICE];
+  }
+
+  return null;
+}

tools/release/version-name/create-version.ts

@@ -2,7 +2,7 @@ import {Version} from './parse-version';
 import {VersionType} from './publish-branch';
 
 /** Type of a new release */
-export type ReleaseType = VersionType | 'stable-release' | 'pre-release' | 'custom-release';
+export type ReleaseType = VersionType | 'stable-release' | 'bump-prerelease';
 
 /** Creates a new version that can be used for the given release type. */
 export function createNewVersion(currentVersion: Version, releaseType: ReleaseType):
@@ -10,7 +10,7 @@ export function createNewVersion(currentVersion: Version, releaseType: ReleaseTy
   // Clone the version object in order to keep the original version info un-modified.
   const newVersion = currentVersion.clone();
 
-  if (releaseType === 'pre-release') {
+  if (releaseType === 'bump-prerelease') {
     newVersion.prereleaseNumber++;
   } else {
     // For all other release types, the pre-release label and number should be removed

tools/release/version-name/parse-version.ts

@@ -51,7 +51,7 @@ export function serializeVersion(newVersion: Version): string {
 
   let versionString = `${major}.${minor}.${patch}`;
 
-  if (prereleaseLabel && prereleaseNumber) {
+  if (prereleaseLabel && !isNaN(prereleaseNumber)) {
     versionString += `-${prereleaseLabel}.${prereleaseNumber}`;
   }