refactor: hammer migration should add "HammerModule" if needed (#17444)

The v9 HammerJS migration should add the `HammerModule` to the
app module if needed.

Additionally if HammerJS is not used in templates (or in general),
we remove references to the "HammerModule". This scenario can happen
if someone updates to v9 Angular while keeping Angular Material v8. In
that case, the author will add the `HammerModule` to the app module and
whenever the update to v9+ Angular Material is performed, the `HammerModule`
is not needed anymore.. so we can remove it automatically.

Author: devversion

src/material/schematics/ng-update/test-cases/v9/hammer-migration-v9.spec.ts

@@ -102,6 +102,41 @@ describe('v9 HammerJS removal', () => {
         export class TestModule {}`);
     });
 
+    it('should remove references to HammerModule', async () => {
+      writeFile('/projects/cdk-testing/src/test.module.ts', dedent`
+        import {NgModule} from '@angular/core';
+        import {HAMMER_GESTURE_CONFIG, HammerModule} from '@angular/platform-browser'; // some comment
+        import {GestureConfig} from '@angular/material/core';
+
+        @NgModule({
+          providers: [
+            {provide: HAMMER_GESTURE_CONFIG, useClass: GestureConfig},
+            OtherProvider,
+          ],
+          imports: [
+            HammerModule,
+            OtherModule
+          ],
+        })
+        export class TestModule {}
+      `);
+
+      await runMigration();
+
+      expect(tree.readContent('/projects/cdk-testing/src/test.module.ts')).toContain(dedent`
+        import {NgModule} from '@angular/core';
+
+        @NgModule({
+          providers: [
+            OtherProvider,
+          ],
+          imports: [
+            OtherModule
+          ],
+        })
+        export class TestModule {}`);
+    });
+
     it('should remove references to gesture config if imports are aliased', async () => {
       writeFile('/projects/cdk-testing/src/test.module.ts', dedent`
         import {NgModule} from '@angular/core';
@@ -318,14 +353,15 @@ describe('v9 HammerJS removal', () => {
 
       writeFile('/projects/cdk-testing/src/test.module.ts', dedent`
         import {NgModule} from '@angular/core';
-        import {HAMMER_GESTURE_CONFIG} from '@angular/platform-browser';
+        import {HAMMER_GESTURE_CONFIG, HammerModule} from '@angular/platform-browser';
         import {GestureConfig} from '@angular/material/core';
 
         @NgModule({
           providers: [
             {provide: HAMMER_GESTURE_CONFIG, useClass: GestureConfig},
             OtherProvider,
-          ]
+          ],
+          imports: [HammerModule],
         })
         export class TestModule {}
       `);
@@ -340,7 +376,8 @@ describe('v9 HammerJS removal', () => {
         @NgModule({
           providers: [
             OtherProvider,
-          ]
+          ],
+          imports: [],
         })
         export class TestModule {}`);
     });
@@ -507,7 +544,7 @@ describe('v9 HammerJS removal', () => {
         export class TestModule {}`);
     });
 
-    it('should add gesture config provider to app module', async () => {
+    it('should set up Hammer gestures in app module', async () => {
       writeFile('/projects/cdk-testing/src/app/app.component.html', `
         <span (pinch)="onPinch($event)"></span>
       `);
@@ -517,7 +554,7 @@ describe('v9 HammerJS removal', () => {
       expect(tree.readContent('/projects/cdk-testing/src/main.ts')).toContain(`import 'hammerjs';`);
       expect(tree.exists('/projects/cdk-testing/src/gesture-config.ts')).toBe(true);
       expect(tree.readContent('/projects/cdk-testing/src/app/app.module.ts')).toContain(dedent`\
-        import { BrowserModule, HAMMER_GESTURE_CONFIG } from '@angular/platform-browser';
+        import { BrowserModule, HammerModule, HAMMER_GESTURE_CONFIG } from '@angular/platform-browser';
         import { NgModule } from '@angular/core';
 
         import { AppComponent } from './app.component';
@@ -528,7 +565,8 @@ describe('v9 HammerJS removal', () => {
             AppComponent
           ],
           imports: [
-            BrowserModule
+            BrowserModule,
+            HammerModule
           ],
           providers: [{ provide: HAMMER_GESTURE_CONFIG, useClass: GestureConfig }],
           bootstrap: [AppComponent]
@@ -565,7 +603,7 @@ describe('v9 HammerJS removal', () => {
       expect(tree.readContent('/projects/cdk-testing/src/main.ts')).toContain(`import 'hammerjs';`);
       expect(tree.exists('/projects/cdk-testing/src/gesture-config.ts')).toBe(true);
       expect(tree.readContent('/projects/cdk-testing/src/app/app.module.ts')).toContain(dedent`\
-        import { BrowserModule, HAMMER_GESTURE_CONFIG } from '@angular/platform-browser';
+        import { BrowserModule, HammerModule, HAMMER_GESTURE_CONFIG } from '@angular/platform-browser';
         import { NgModule } from '@angular/core';
 
         import { AppComponent } from './app.component';
@@ -576,7 +614,8 @@ describe('v9 HammerJS removal', () => {
             AppComponent
           ],
           imports: [
-            BrowserModule
+            BrowserModule,
+            HammerModule
           ],
           providers: [{ provide: HAMMER_GESTURE_CONFIG, useClass: GestureConfig }],
           bootstrap: [AppComponent]
@@ -610,7 +649,7 @@ describe('v9 HammerJS removal', () => {
       expect(tree.readContent('/projects/cdk-testing/src/main.ts')).toContain(`import 'hammerjs';`);
       expect(tree.exists('/projects/cdk-testing/src/gesture-config.ts')).toBe(true);
       expect(tree.readContent('/projects/cdk-testing/src/app/app.module.ts')).toContain(dedent`
-        import {HAMMER_GESTURE_CONFIG} from '@angular/platform-browser';
+        import { HAMMER_GESTURE_CONFIG, HammerModule } from '@angular/platform-browser';
         import {NgModule} from '@angular/core';
         import { GestureConfig } from "../gesture-config";
 
@@ -621,6 +660,38 @@ describe('v9 HammerJS removal', () => {
               useClass: GestureConfig
             },
           ],
+          imports: [HammerModule],
+        })
+        export class AppModule {}`);
+    });
+
+    it('should not add HammerModule multiple times if already provided', async () => {
+      writeFile('/projects/cdk-testing/src/app/app.component.html', `
+        <span (pinch)="onPinch($event)"></span>
+      `);
+
+      writeFile('/projects/cdk-testing/src/app/app.module.ts', dedent`
+        import {HammerModule as myHammerModule} from '@angular/platform-browser';
+        import {NgModule} from '@angular/core';
+
+        @NgModule({
+          imports: [myHammerModule],
+        })
+        export class AppModule {}
+      `);
+
+      await runMigration();
+
+      expect(tree.readContent('/projects/cdk-testing/src/main.ts')).toContain(`import 'hammerjs';`);
+      expect(tree.exists('/projects/cdk-testing/src/gesture-config.ts')).toBe(true);
+      expect(tree.readContent('/projects/cdk-testing/src/app/app.module.ts')).toContain(dedent`
+        import { HammerModule as myHammerModule, HAMMER_GESTURE_CONFIG } from '@angular/platform-browser';
+        import {NgModule} from '@angular/core';
+        import { GestureConfig } from "../gesture-config";
+
+        @NgModule({
+          imports: [myHammerModule],
+          providers: [{ provide: HAMMER_GESTURE_CONFIG, useClass: GestureConfig }],
         })
         export class AppModule {}`);
     });
@@ -710,8 +781,8 @@ describe('v9 HammerJS removal', () => {
 
        const {logOutput} = await runMigration();
 
-       expect(logOutput).toContain(
-          `Material gesture config is used while a custom gesture config is set up`);
+       expect(logOutput).toContain(`unable to perform the full migration for this target, but ` +
+         `removed all references to the deprecated Angular Material gesture config.`);
        expect(tree.readContent('/projects/cdk-testing/src/main.ts')).toContain('hammerjs');
        expect(tree.readContent('/projects/cdk-testing/src/test.component.ts')).toContain(dedent`
          import {HAMMER_GESTURE_CONFIG} from '@angular/platform-browser';