feat(@schematics/angular): generate libraries using TypeScript project references

When generating a project (via `ng generate library`), the
created TypeScript configuration files (`tsconfig.lib.json`/`tsconfig.spec.json`)
will be setup as composite projects and added as project references in the root
`tsconfig.json`.  This transforms the root `tsconfig.json` into a "solution" style
configuration. This allows IDEs to more accurately discover and provide type information
for the varying types of files (test, library, etc.) within each project.
The Angular build process is otherwise unaffected by these changes.

Author: clydin

packages/schematics/angular/library/files/tsconfig.lib.json.template

@@ -9,6 +9,9 @@
     "inlineSources": true,
     "types": []
   },
+  "include": [
+    "src/**/*.ts"
+  ],
   "exclude": [
     "**/*.spec.ts"
   ]

packages/schematics/angular/library/files/tsconfig.spec.json.template

@@ -9,7 +9,6 @@
     ]
   },
   "include": [
-    "**/*.spec.ts",
-    "**/*.d.ts"
+    "src/**/*.ts"
   ]
 }

packages/schematics/angular/library/index.ts

@@ -43,6 +43,21 @@ function updateTsConfig(packageName: string, ...paths: string[]) {
   };
 }
 
+function addTsProjectReference(...paths: string[]) {
+  return (host: Tree) => {
+    if (!host.exists('tsconfig.json')) {
+      return host;
+    }
+
+    const newReferences = paths.map((path) => ({ path }));
+
+    const file = new JSONFile(host, 'tsconfig.json');
+    const jsonPath = ['references'];
+    const value = file.get(jsonPath);
+    file.modify(jsonPath, Array.isArray(value) ? [...value, ...newReferences] : newReferences);
+  };
+}
+
 function addDependenciesToPackageJson() {
   return (host: Tree) => {
     [
@@ -162,6 +177,12 @@ export default function (options: LibraryOptions): Rule {
       addLibToWorkspaceFile(options, libDir, packageName),
       options.skipPackageJson ? noop() : addDependenciesToPackageJson(),
       options.skipTsConfig ? noop() : updateTsConfig(packageName, './' + distRoot),
+      options.skipTsConfig
+        ? noop()
+        : addTsProjectReference(
+            './' + join(libDir, 'tsconfig.lib.json'),
+            './' + join(libDir, 'tsconfig.spec.json'),
+          ),
       options.standalone
         ? noop()
         : schematic('module', {

packages/schematics/angular/library/index_spec.ts

@@ -293,6 +293,24 @@ describe('Library Schematic', () => {
 
       const tsConfigJson = getJsonFileContent(tree, 'tsconfig.json');
       expect(tsConfigJson.compilerOptions.paths).toBeUndefined();
+      expect(tsConfigJson.references).not.toContain(
+        jasmine.objectContaining({ path: './projects/foo/tsconfig.lib.json' }),
+      );
+      expect(tsConfigJson.references).not.toContain(
+        jasmine.objectContaining({ path: './projects/foo/tsconfig.spec.json' }),
+      );
+    });
+
+    it('should add project references in the root tsconfig.json', async () => {
+      const tree = await schematicRunner.runSchematic('library', defaultOptions, workspaceTree);
+
+      const { references } = getJsonFileContent(tree, '/tsconfig.json');
+      expect(references).toContain(
+        jasmine.objectContaining({ path: './projects/foo/tsconfig.lib.json' }),
+      );
+      expect(references).toContain(
+        jasmine.objectContaining({ path: './projects/foo/tsconfig.spec.json' }),
+      );
     });
   });