feat(rush): add support for resolution only mode with pnpm

common/changes/@microsoft/rush/sennyeya-resolution-only-for-install_2024-08-16-16-38.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/rush",
+      "comment": "Add support for `--resolution-only` to `rush install` to enforce strict peer dependency resolution.",
+      "type": "none"
+    }
+  ],
+  "packageName": "@microsoft/rush"
+}

common/config/rush/experiments.json

@@ -9,7 +9,7 @@
    * By default, 'rush install' passes --no-prefer-frozen-lockfile to 'pnpm install'.
    * Set this option to true to pass '--frozen-lockfile' instead for faster installs.
    */
-  "usePnpmFrozenLockfileForRushInstall": true,
+  // "usePnpmFrozenLockfileForRushInstall": true,
 
   /**
    * By default, 'rush update' passes --no-prefer-frozen-lockfile to 'pnpm install'.

libraries/rush-lib/src/api/test/__snapshots__/RushCommandLine.test.ts.snap

@@ -462,6 +462,14 @@ Object {
           "required": false,
           "shortName": undefined,
         },
+        Object {
+          "description": "Only perform dependency resolution, useful for ensuring peer dependendencies are up to date.",
+          "environmentVariable": undefined,
+          "kind": "Flag",
+          "longName": "--resolution-only",
+          "required": false,
+          "shortName": undefined,
+        },
       ],
     },
     Object {

libraries/rush-lib/src/cli/actions/InstallAction.ts

@@ -11,6 +11,7 @@ import type { RushConfigurationProject } from '../../api/RushConfigurationProjec
 
 export class InstallAction extends BaseInstallAction {
   private readonly _checkOnlyParameter: CommandLineFlagParameter;
+  private readonly _resolutionOnlyParameter: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -45,6 +46,11 @@ export class InstallAction extends BaseInstallAction {
       parameterLongName: '--check-only',
       description: `Only check the validity of the shrinkwrap file without performing an install.`
     });
+
+    this._resolutionOnlyParameter = this.defineFlagParameter({
+      parameterLongName: '--resolution-only',
+      description: `Only perform dependency resolution, useful for ensuring peer dependendencies are up to date.`
+    });
   }
 
   protected async buildInstallOptionsAsync(): Promise<Omit<IInstallManagerOptions, 'subspace'>> {
@@ -71,6 +77,7 @@ export class InstallAction extends BaseInstallAction {
       pnpmFilterArgumentValues:
         (await this._selectionParameters?.getPnpmFilterArgumentValuesAsync(this._terminal)) ?? [],
       checkOnly: this._checkOnlyParameter.value,
+      resolutionOnly: this._resolutionOnlyParameter.value,
       beforeInstallAsync: () => this.rushSession.hooks.beforeInstall.promise(this),
       terminal: this._terminal
     };

libraries/rush-lib/src/cli/test/__snapshots__/CommandLineHelp.test.ts.snap

@@ -627,6 +627,7 @@ exports[`CommandLineHelp prints the help for each action: install 1`] = `
                     [--to-version-policy VERSION_POLICY_NAME]
                     [--from-version-policy VERSION_POLICY_NAME]
                     [--subspace SUBSPACE_NAME] [--check-only]
+                    [--resolution-only]
 
 
 The \\"rush install\\" command installs package dependencies for all your 
@@ -755,6 +756,8 @@ Optional arguments:
                         be enabled in subspaces.json.
   --check-only          Only check the validity of the shrinkwrap file 
                         without performing an install.
+  --resolution-only     Only perform dependency resolution, useful for 
+                        ensuring peer dependendencies are up to date.
 "
 `;
 

libraries/rush-lib/src/logic/base/BaseInstallManager.ts

@@ -745,12 +745,18 @@ ${gitLfsHookHandling}
       pnpmFilterArgumentValues,
       onlyShrinkwrap,
       networkConcurrency,
-      allowShrinkwrapUpdates
+      allowShrinkwrapUpdates,
+      resolutionOnly
     } = options;
 
     if (offline && this.rushConfiguration.packageManager !== 'pnpm') {
       throw new Error('The "--offline" parameter is only supported when using the PNPM package manager.');
     }
+    if (resolutionOnly && this.rushConfiguration.packageManager !== 'pnpm') {
+      throw new Error(
+        'The "--resolution-only" parameter is only supported when using the PNPM package manager.'
+      );
+    }
     if (this.rushConfiguration.packageManager === 'npm') {
       if (semver.lt(this.rushConfiguration.packageManagerToolVersion, '5.0.0')) {
         // NOTE:
@@ -842,6 +848,10 @@ ${gitLfsHookHandling}
         args.push('--strict-peer-dependencies');
       }
 
+      if (resolutionOnly) {
+        args.push('--resolution-only');
+      }
+
       /*
         If user set auto-install-peers in pnpm-config.json only, use the value in pnpm-config.json
         If user set auto-install-peers in pnpm-config.json and .npmrc, use the value in pnpm-config.json

libraries/rush-lib/src/logic/base/BaseInstallManagerTypes.ts

@@ -22,6 +22,11 @@ export interface IInstallManagerOptions {
    */
   checkOnly: boolean;
 
+  /**
+   * Whether to only run resolutions. Only supported for PNPM.
+   */
+  resolutionOnly?: boolean;
+
   /**
    * Whether a "--bypass-policy" flag can be specified.
    */