fix(@schematics/angular): ensure module discovery checks for an NgModule decorator

The Angular module discovery logic previously did not check for the presence
of a potential `@NgModule` decorator. This can cause false positive results
for files with a module-like naming pattern.

Author: clydin

packages/schematics/angular/utility/find-module.ts

@@ -59,7 +59,7 @@ export function findModuleFromOptions(host: Tree, options: ModuleOptions): Path
       );
 
       for (const sc of candidateFiles) {
-        if (host.exists(sc)) {
+        if (host.exists(sc) && host.readText(sc).includes('@NgModule')) {
           return normalize(sc);
         }
       }

packages/schematics/angular/utility/find-module_spec.ts

@@ -92,32 +92,41 @@ describe('find-module', () => {
       options = { name: 'foo' };
     });
 
-    it('should find a module', () => {
-      tree.create('/projects/my-proj/src/app.module.ts', '');
+    it('should find a module with a decorator', () => {
+      tree.create('/projects/my-proj/src/app.module.ts', '@NgModule');
       options.module = 'app.module.ts';
       options.path = '/projects/my-proj/src';
       const modPath = findModuleFromOptions(tree, options) as string;
       expect(modPath).toEqual('/projects/my-proj/src/app.module.ts');
     });
 
+    it('should not find module-like file without a decorator', () => {
+      tree.create('/projects/my-proj/src/app.module.ts', '');
+      options.module = 'app.module.ts';
+      options.path = '/projects/my-proj/src';
+      expect(() => findModuleFromOptions(tree, options) as string).toThrowError(
+        /Specified module 'app.module.ts' does not exist/,
+      );
+    });
+
     it('should find a module when name has underscore', () => {
-      tree.create('/projects/my-proj/src/feature_module/app_test.module.ts', '');
+      tree.create('/projects/my-proj/src/feature_module/app_test.module.ts', '@NgModule');
       options.path = '/projects/my-proj/src';
       options.name = 'feature_module/new_component';
       const modPath = findModuleFromOptions(tree, options) as string;
       expect(modPath).toEqual('/projects/my-proj/src/feature_module/app_test.module.ts');
     });
 
     it('should find a module when name has uppercase', () => {
-      tree.create('/projects/my-proj/src/featureModule/appTest.module.ts', '');
+      tree.create('/projects/my-proj/src/featureModule/appTest.module.ts', '@NgModule');
       options.path = '/projects/my-proj/src';
       options.name = 'featureModule/newComponent';
       const modPath = findModuleFromOptions(tree, options) as string;
       expect(modPath).toEqual('/projects/my-proj/src/featureModule/appTest.module.ts');
     });
 
     it('should find a module if flat is true', () => {
-      tree.create('/projects/my-proj/src/module/app_test.module.ts', '');
+      tree.create('/projects/my-proj/src/module/app_test.module.ts', '@NgModule');
       options.path = '/projects/my-proj/src';
       options.flat = true;
       options.name = '/module/directive';
@@ -126,7 +135,7 @@ describe('find-module', () => {
     });
 
     it('should find a module in a sub dir', () => {
-      tree.create('/projects/my-proj/src/admin/foo.module.ts', '');
+      tree.create('/projects/my-proj/src/admin/foo.module.ts', '@NgModule');
       options.name = 'other/test';
       options.module = 'admin/foo';
       options.path = '/projects/my-proj/src';
@@ -135,7 +144,7 @@ describe('find-module', () => {
     });
 
     it('should find a module in a sub dir (2)', () => {
-      tree.create('/projects/my-proj/src/admin/foo.module.ts', '');
+      tree.create('/projects/my-proj/src/admin/foo.module.ts', '@NgModule');
       options.name = 'admin/hello';
       options.module = 'foo';
       options.path = '/projects/my-proj/src';
@@ -144,7 +153,7 @@ describe('find-module', () => {
     });
 
     it('should find a module using custom ext', () => {
-      tree.create('/projects/my-proj/src/app_module.ts', '');
+      tree.create('/projects/my-proj/src/app_module.ts', '@NgModule');
       options.module = 'app';
       options.path = '/projects/my-proj/src';
       options.moduleExt = '_module.ts';
@@ -164,7 +173,7 @@ describe('find-module', () => {
     });
 
     it('should ignore custom ext if module or ${module}.ts exists', () => {
-      tree.create('/projects/my-proj/src/app.module.ts', '');
+      tree.create('/projects/my-proj/src/app.module.ts', '@NgModule');
       options.path = '/projects/my-proj/src';
       options.moduleExt = '_module.ts';
       let modPath;