add support to custom package.json install and watch.

src/environment-base.ts

@@ -739,6 +739,59 @@ export default class EnvironmentBase extends EventEmitter implements BaseEnviron
     }, match);
   }
 
+  /**
+   * Watch for package.json and queue package manager install task.
+   */
+  public watchForPackageManagerInstall({
+    cwd,
+    queueTask,
+    installTask,
+  }: {
+    cwd?: string;
+    queueTask?: boolean;
+    installTask?: (nodePackageManager: string | undefined, defaultTask: () => Promise<boolean>) => void | Promise<void>;
+  } = {}) {
+    if (cwd && !installTask) {
+      throw new Error(`installTask is required when using a custom cwd`);
+    }
+
+    const npmCwd = cwd ?? this.cwd;
+
+    const queueInstallTask = () => {
+      this.queueTask(
+        'install',
+        async () => {
+          if (this.compatibilityMode === 'v4') {
+            debug('Running in generator < 5 compatibility. Package manager install is done by the generator.');
+            return;
+          }
+
+          const { adapter, sharedFs: memFs } = this;
+          const { skipInstall, nodePackageManager } = this.options;
+          await packageManagerInstallTask({
+            adapter,
+            memFs,
+            packageJsonLocation: npmCwd,
+            skipInstall,
+            nodePackageManager,
+            customInstallTask: installTask ?? this.composedStore.customInstallTask,
+          });
+        },
+        { once: `package manager install ${npmCwd}` },
+      );
+    };
+
+    this.sharedFs.on('change', file => {
+      if (file === join(npmCwd, 'package.json')) {
+        queueInstallTask();
+      }
+    });
+
+    if (queueTask) {
+      queueInstallTask();
+    }
+  }
+
   /**
    * Start Environment queue
    * @param {Object} options - Conflicter options.
@@ -751,7 +804,10 @@ export default class EnvironmentBase extends EventEmitter implements BaseEnviron
       this.conflicterOptions.cwd = this.logCwd;
 
       this.queueCommit();
-      this.queuePackageManagerInstall();
+      this.queueTask('install', () => {
+        // Postpone watchForPackageManagerInstall to install priority since env's cwd can be changed by generators
+        this.watchForPackageManagerInstall({ queueTask: true });
+      });
 
       /*
        * Listen to errors and reject if emmited.
@@ -834,38 +890,6 @@ export default class EnvironmentBase extends EventEmitter implements BaseEnviron
     queueCommit();
   }
 
-  /**
-   * Queue environment's package manager install task.
-   */
-  protected queuePackageManagerInstall() {
-    this.queueTask(
-      'install',
-      async () => {
-        if (this.compatibilityMode === 'v4') {
-          debug('Running in generator < 5 compatibility. Package manager install is done by the generator.');
-          return;
-        }
-
-        const { adapter, sharedFs: memFs } = this;
-        const { skipInstall, nodePackageManager } = this.options;
-        const { customInstallTask } = this.composedStore;
-        await packageManagerInstallTask({
-          adapter,
-          memFs,
-          packageJsonLocation: this.cwd,
-          skipInstall,
-          nodePackageManager,
-          customInstallTask,
-        });
-
-        memFs.once('change', file => {
-          if (file === join(this.cwd, 'package.json')) this.queuePackageManagerInstall();
-        });
-      },
-      { once: 'package manager install' },
-    );
-  }
-
   /**
    * Registers a specific `generator` to this environment. This generator is stored under
    * provided namespace, or a default namespace format if none if available.

test/generator-features.js

@@ -201,7 +201,6 @@ describe('environment (generator-features)', () => {
                 }
 
                 packageJsonTask() {
-                  console.log('foo');
                   this.packageJson.set({ name: 'foo' });
                 }
               },
@@ -223,5 +222,58 @@ describe('environment (generator-features)', () => {
         assert.equal(typeof customInstallTask.getCall(0).args[1], 'function');
       });
     });
+
+    describe('with function customInstallTask and custom path', () => {
+      let runContext;
+      let customInstallTask;
+      let installTask;
+      beforeEach(async () => {
+        customInstallTask = sinon.stub();
+        installTask = (pm, defaultTask) => defaultTask(pm);
+        runContext = helpers
+          .create('custom-install', undefined, { createEnv: getCreateEnv(BasicEnvironment) })
+          .withOptions({ skipInstall: false })
+          .withGenerators([
+            [
+              class extends FeaturesGenerator {
+                constructor(args, options) {
+                  super(args, options, { customInstallTask });
+                  this.destinationRoot(this.destinationPath('foo'));
+                  this.env.watchForPackageManagerInstall({
+                    cwd: this.destinationPath(),
+                    installTask,
+                  });
+                }
+
+                packageJsonTask() {
+                  this.packageJson.set({ name: 'foo' });
+                }
+              },
+              { namespace: 'custom-install:app' },
+            ],
+          ]);
+        await runContext.run();
+      });
+
+      it('should not call customInstallTask', () => {
+        assert.equal(customInstallTask.callCount, 0, 'should not have been called');
+      });
+
+      it('should call packageManagerInstallTask twice', () => {
+        expect(packageManagerInstallTask).toHaveBeenCalledTimes(2);
+        expect(packageManagerInstallTask).toHaveBeenNthCalledWith(
+          2,
+          expect.objectContaining({
+            customInstallTask,
+          }),
+        );
+        expect(packageManagerInstallTask).toHaveBeenNthCalledWith(
+          1,
+          expect.objectContaining({
+            customInstallTask: installTask,
+          }),
+        );
+      });
+    });
   });
 });