feat(material/sidenav/testing): polish harness API (#17415)

Author: mmalerba

src/material/sidenav/testing/drawer-harness-filters.ts

@@ -8,4 +8,6 @@
 
 import {BaseHarnessFilters} from '@angular/cdk/testing';
 
-export interface DrawerHarnessFilters extends BaseHarnessFilters {}
+export interface DrawerHarnessFilters extends BaseHarnessFilters {
+  position?: 'start' | 'end';
+}

src/material/sidenav/testing/drawer-harness.ts

@@ -23,7 +23,9 @@ export class MatDrawerHarness extends ComponentHarness {
    * @return `HarnessPredicate` configured with the given options.
    */
   static with(options: DrawerHarnessFilters = {}): HarnessPredicate<MatDrawerHarness> {
-    return new HarnessPredicate(MatDrawerHarness, options);
+    return new HarnessPredicate(MatDrawerHarness, options)
+        .addOption('position', options.position,
+            async (harness, position) => (await harness.getPosition()) === position);
   }
 
   /** Gets whether the drawer is open. */

src/material/sidenav/testing/shared.spec.ts

@@ -31,6 +31,12 @@ export function runHarnessTests(sidenavModule: typeof MatSidenavModule,
       expect(drawers.length).toBe(3);
     });
 
+    it('should load drawer harness based on position', async () => {
+      const drawers = await loader.getAllHarnesses(drawerHarness.with({position: 'end'}));
+      expect(drawers.length).toBe(1);
+      expect(await (await drawers[0].host()).text()).toBe('Two');
+    });
+
     it('should be able to get whether the drawer is open', async () => {
       const drawers = await loader.getAllHarnesses(drawerHarness);
 

src/material/sidenav/testing/sidenav-harness.ts

@@ -24,7 +24,9 @@ export class MatSidenavHarness extends MatDrawerHarness {
    * @return `HarnessPredicate` configured with the given options.
    */
   static with(options: DrawerHarnessFilters = {}): HarnessPredicate<MatDrawerHarness> {
-    return new HarnessPredicate(MatDrawerHarness, options);
+    return new HarnessPredicate(MatDrawerHarness, options)
+        .addOption('position', options.position,
+            async (harness, position) => (await harness.getPosition()) === position);
   }
 
   /** Gets whether the sidenav is fixed in the viewport. */