fix(@angular-devkit/architect): explicitly type functions

Closes: #11992

Author: hansl

packages/angular_devkit/architect/testing/test-project-host.ts

@@ -8,6 +8,7 @@
 
 import {
   Path,
+  PathFragment,
   basename,
   dirname,
   join,
@@ -128,7 +129,7 @@ export class TestProjectHost extends NodeJsSyncHost {
       virtualFs.stringToFileBuffer(content.concat(str)));
   }
 
-  fileMatchExists(dir: string, regex: RegExp) {
+  fileMatchExists(dir: string, regex: RegExp): PathFragment | undefined {
     const [fileName] = this.scopedSync().list(normalize(dir)).filter(name => name.match(regex));
 
     return fileName || undefined;

packages/angular_devkit/build_angular/test/utils.ts

@@ -7,13 +7,13 @@
  */
 
 import { TestProjectHost } from '@angular-devkit/architect/testing';
-import { join, normalize } from '@angular-devkit/core';
+import { Path, join, normalize } from '@angular-devkit/core';
 
 
 const devkitRoot = normalize((global as any)._DevKitRoot); // tslint:disable-line:no-any
 const workspaceRoot = join(devkitRoot, 'tests/angular_devkit/build_angular/hello-world-app/');
 export const host = new TestProjectHost(workspaceRoot);
-export const outputPath = normalize('dist');
+export const outputPath: Path = normalize('dist');
 
 export const browserTargetSpec = { project: 'app', target: 'build' };
 export const devServerTargetSpec = { project: 'app', target: 'serve' };

packages/angular_devkit/core/src/virtual-fs/host/test.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 import { Observable } from 'rxjs';
-import { Path, join, normalize } from '../path';
+import { Path, PathFragment, join, normalize } from '../path';
 import { fileBufferToString, stringToFileBuffer } from './buffer';
 import { FileBuffer, HostWatchEvent, HostWatchOptions, Stats } from './interface';
 import { SimpleMemoryHost, SimpleMemoryHostStats } from './memory';
@@ -96,7 +96,7 @@ export class TestHost extends SimpleMemoryHost {
 
     return super._rename(from, to);
   }
-  protected _list(path: Path) {
+  protected _list(path: Path): PathFragment[] {
     this._records.push({ kind: 'list', path });
 
     return super._list(path);
@@ -135,7 +135,7 @@ export class TestHost extends SimpleMemoryHost {
     return fileBufferToString(super._read(normalize(path)));
   }
 
-  $list(path: string) {
+  $list(path: string): PathFragment[] {
     return super._list(normalize(path));
   }