From d22355b37741ecc4dec9dcef188b49570fb27f33 Mon Sep 17 00:00:00 2001
From: Cheng-Hsuan Tsai <webcat@google.com>
Date: Tue, 7 Apr 2026 23:23:47 +0000
Subject: [PATCH 1/4] feat(aria/accordion): introduce accordion harness

---
 goldens/aria/accordion/testing/index.api.md   |  58 +++++++
 src/aria/accordion/BUILD.bazel                |   3 +
 src/aria/accordion/testing/BUILD.bazel        |  42 +++++
 .../testing/accordion-harness.spec.ts         | 124 ++++++++++++++
 .../accordion/testing/accordion-harness.ts    | 155 ++++++++++++++++++
 src/aria/accordion/testing/index.ts           |   9 +
 src/aria/accordion/testing/public-api.ts      |   9 +
 src/aria/config.bzl                           |   1 +
 8 files changed, 401 insertions(+)
 create mode 100644 goldens/aria/accordion/testing/index.api.md
 create mode 100644 src/aria/accordion/testing/BUILD.bazel
 create mode 100644 src/aria/accordion/testing/accordion-harness.spec.ts
 create mode 100644 src/aria/accordion/testing/accordion-harness.ts
 create mode 100644 src/aria/accordion/testing/index.ts
 create mode 100644 src/aria/accordion/testing/public-api.ts

diff --git a/goldens/aria/accordion/testing/index.api.md b/goldens/aria/accordion/testing/index.api.md
new file mode 100644
index 000000000000..8e7cbe63088d
--- /dev/null
+++ b/goldens/aria/accordion/testing/index.api.md
@@ -0,0 +1,58 @@
+## API Report File for "@angular/aria_accordion_testing"
+
+> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
+
+```ts
+
+import { BaseHarnessFilters } from '@angular/cdk/testing';
+import { ComponentHarness } from '@angular/cdk/testing';
+import { HarnessPredicate } from '@angular/cdk/testing';
+
+// @public
+export class AccordionGroupHarness extends ComponentHarness {
+    getPanels(filters?: AccordionPanelHarnessFilters): Promise<AccordionPanelHarness[]>;
+    getTriggers(filters?: AccordionTriggerHarnessFilters): Promise<AccordionTriggerHarness[]>;
+    static hostSelector: string;
+    static with(options?: AccordionGroupHarnessFilters): HarnessPredicate<AccordionGroupHarness>;
+}
+
+// @public
+export interface AccordionGroupHarnessFilters extends BaseHarnessFilters {
+}
+
+// @public
+export class AccordionPanelHarness extends ComponentHarness {
+    getText(): Promise<string>;
+    static hostSelector: string;
+    isExpanded(): Promise<boolean>;
+    static with(options?: AccordionPanelHarnessFilters): HarnessPredicate<AccordionPanelHarness>;
+}
+
+// @public
+export interface AccordionPanelHarnessFilters extends BaseHarnessFilters {
+    trigger?: AccordionTriggerHarness;
+}
+
+// @public
+export class AccordionTriggerHarness extends ComponentHarness {
+    blur(): Promise<void>;
+    click(): Promise<void>;
+    focus(): Promise<void>;
+    getText(): Promise<string>;
+    static hostSelector: string;
+    isDisabled(): Promise<boolean>;
+    isExpanded(): Promise<boolean>;
+    isFocused(): Promise<boolean>;
+    static with(options?: AccordionTriggerHarnessFilters): HarnessPredicate<AccordionTriggerHarness>;
+}
+
+// @public
+export interface AccordionTriggerHarnessFilters extends BaseHarnessFilters {
+    disabled?: boolean;
+    expanded?: boolean;
+    text?: string | RegExp;
+}
+
+// (No @packageDocumentation comment for this package)
+
+```
diff --git a/src/aria/accordion/BUILD.bazel b/src/aria/accordion/BUILD.bazel
index 51ffb8340196..59483aa59b55 100644
--- a/src/aria/accordion/BUILD.bazel
+++ b/src/aria/accordion/BUILD.bazel
@@ -13,6 +13,7 @@ ng_project(
         "//src/aria/private",
         "//src/cdk/a11y",
         "//src/cdk/bidi",
+        "//src/cdk/testing",
     ],
 )
 
@@ -26,7 +27,9 @@ ng_project(
         ":accordion",
         "//:node_modules/@angular/core",
         "//:node_modules/@angular/platform-browser",
+        "//src/cdk/testing",
         "//src/cdk/testing/private",
+        "//src/cdk/testing/testbed",
     ],
 )
 
diff --git a/src/aria/accordion/testing/BUILD.bazel b/src/aria/accordion/testing/BUILD.bazel
new file mode 100644
index 000000000000..daefc5897c1a
--- /dev/null
+++ b/src/aria/accordion/testing/BUILD.bazel
@@ -0,0 +1,42 @@
+load("//tools:defaults.bzl", "ng_project", "ng_web_test_suite", "ts_project")
+
+package(default_visibility = ["//visibility:public"])
+
+ts_project(
+    name = "testing",
+    srcs = glob(
+        ["**/*.ts"],
+        exclude = ["**/*.spec.ts"],
+    ),
+    deps = [
+        "//:node_modules/@angular/core",
+        "//src/cdk/testing",
+    ],
+)
+
+filegroup(
+    name = "source-files",
+    srcs = glob(["**/*.ts"]),
+)
+
+ng_project(
+    name = "unit_tests_lib",
+    testonly = True,
+    srcs = glob(["**/*.spec.ts"]),
+    deps = [
+        ":testing",
+        "//:node_modules/@angular/core",
+        "//:node_modules/@angular/platform-browser",
+        "//src/aria/accordion",
+        "//src/cdk/testing",
+        "//src/cdk/testing/private",
+        "//src/cdk/testing/testbed",
+    ],
+)
+
+ng_web_test_suite(
+    name = "unit_tests",
+    deps = [
+        ":unit_tests_lib",
+    ],
+)
diff --git a/src/aria/accordion/testing/accordion-harness.spec.ts b/src/aria/accordion/testing/accordion-harness.spec.ts
new file mode 100644
index 000000000000..a55768d4d383
--- /dev/null
+++ b/src/aria/accordion/testing/accordion-harness.spec.ts
@@ -0,0 +1,124 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import {Component} from '@angular/core';
+import {TestBed} from '@angular/core/testing';
+import {TestbedHarnessEnvironment} from '@angular/cdk/testing/testbed';
+import {
+  AccordionTriggerHarness,
+  AccordionPanelHarness,
+  AccordionGroupHarness,
+} from './accordion-harness';
+import {AccordionGroup, AccordionPanel, AccordionTrigger} from '../index';
+
+describe('Accordion Harnesses', () => {
+  let fixture: any;
+  let loader: any;
+
+  @Component({
+    imports: [AccordionGroup, AccordionPanel, AccordionTrigger],
+    template: `
+      <div ngAccordionGroup>
+        <div #panel1="ngAccordionPanel" ngAccordionPanel>Content 1</div>
+        <button ngAccordionTrigger [panel]="panel1">Section 1</button>
+
+        <div #panel2="ngAccordionPanel" ngAccordionPanel>Content 2</div>
+        <button ngAccordionTrigger [panel]="panel2" disabled>Section 2</button>
+      </div>
+    `,
+  })
+  class AccordionHarnessTestComponent {}
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({
+      imports: [AccordionHarnessTestComponent],
+    });
+    fixture = TestBed.createComponent(AccordionHarnessTestComponent);
+    fixture.detectChanges();
+    loader = TestbedHarnessEnvironment.loader(fixture);
+  });
+
+  it('should find all accordion triggers', async () => {
+    const triggers = await loader.getAllHarnesses(AccordionTriggerHarness);
+    expect(triggers.length).toBe(2);
+  });
+
+  it('should support focusing and blurring accordion triggers', async () => {
+    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
+    await trigger.focus();
+    expect(await trigger.isFocused()).toBeTrue();
+
+    await trigger.blur();
+    expect(await trigger.isFocused()).toBeFalse();
+  });
+
+  it('should correctly report the disabled state of a trigger', async () => {
+    const activeTrigger = await loader.getHarness(
+      AccordionTriggerHarness.with({text: 'Section 1'}),
+    );
+    const disabledTrigger = await loader.getHarness(
+      AccordionTriggerHarness.with({text: 'Section 2'}),
+    );
+
+    expect(await activeTrigger.isDisabled()).toBeFalse();
+    expect(await disabledTrigger.isDisabled()).toBeTrue();
+  });
+
+  it('should correctly report the expanded state of a trigger', async () => {
+    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
+    expect(await trigger.isExpanded()).toBeFalse();
+
+    await trigger.click();
+    expect(await trigger.isExpanded()).toBeTrue();
+  });
+
+  it('should filter triggers by disabled state', async () => {
+    const disabledTriggers = await loader.getAllHarnesses(
+      AccordionTriggerHarness.with({disabled: true}),
+    );
+    expect(disabledTriggers.length).toBe(1);
+    expect(await disabledTriggers[0].getText()).toBe('Section 2');
+  });
+
+  it('should filter triggers by expanded state', async () => {
+    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
+    await trigger.click();
+
+    const expandedTriggers = await loader.getAllHarnesses(
+      AccordionTriggerHarness.with({expanded: true}),
+    );
+    expect(expandedTriggers.length).toBe(1);
+    expect(await expandedTriggers[0].getText()).toBe('Section 1');
+  });
+
+  it('should find the panel associated with a specific trigger', async () => {
+    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
+    const panel = await loader.getHarness(AccordionPanelHarness.with({trigger}));
+
+    expect(await panel.getText()).toBe('Content 1');
+  });
+
+  it('should correctly report the expanded state of an accordion panel', async () => {
+    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
+    const panel = await loader.getHarness(AccordionPanelHarness.with({trigger}));
+
+    expect(await panel.isExpanded()).toBeFalse();
+
+    await trigger.click();
+    expect(await panel.isExpanded()).toBeTrue();
+  });
+
+  it('should find accordion group and list scoped triggers and panels', async () => {
+    const group = await loader.getHarness(AccordionGroupHarness);
+    const triggers = await group.getTriggers();
+    const panels = await group.getPanels();
+
+    expect(triggers.length).toBe(2);
+    expect(panels.length).toBe(2);
+  });
+});
diff --git a/src/aria/accordion/testing/accordion-harness.ts b/src/aria/accordion/testing/accordion-harness.ts
new file mode 100644
index 000000000000..1b8fdfcdd0b9
--- /dev/null
+++ b/src/aria/accordion/testing/accordion-harness.ts
@@ -0,0 +1,155 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import {ComponentHarness, HarnessPredicate, BaseHarnessFilters} from '@angular/cdk/testing';
+
+/** Filters for locating an `AccordionTriggerHarness`. */
+export interface AccordionTriggerHarnessFilters extends BaseHarnessFilters {
+  /** Only find instances whose text matches the given value. */
+  text?: string | RegExp;
+  /** Only find instances whose expanded state matches the given value. */
+  expanded?: boolean;
+  /** Only find instances whose disabled state matches the given value. */
+  disabled?: boolean;
+}
+
+/** Filters for locating an `AccordionPanelHarness`. */
+export interface AccordionPanelHarnessFilters extends BaseHarnessFilters {
+  /** Find the panel associated with the given trigger harness. */
+  trigger?: AccordionTriggerHarness;
+}
+
+/** Filters for locating an `AccordionGroupHarness`. */
+export interface AccordionGroupHarnessFilters extends BaseHarnessFilters {}
+
+/** Harness for interacting with an `ngAccordionPanel` in tests. */
+export class AccordionPanelHarness extends ComponentHarness {
+  /** The selector for the host element of an `ngAccordionPanel` instance. */
+  static hostSelector = '[ngAccordionPanel]';
+
+  /**
+   * Gets a `HarnessPredicate` that can be used to search for a panel with specific attributes.
+   * @param options Options for narrowing the search.
+   * @return a `HarnessPredicate` configured with the given options.
+   */
+  static with(options: AccordionPanelHarnessFilters = {}): HarnessPredicate<AccordionPanelHarness> {
+    return new HarnessPredicate(AccordionPanelHarness, options).addOption(
+      'trigger',
+      options.trigger,
+      async (harness, trigger) => {
+        const targetPanelId = await (await trigger.host()).getAttribute('aria-controls');
+        const panelId = await (await harness.host()).getAttribute('id');
+        return panelId === targetPanelId;
+      },
+    );
+  }
+
+  /** Gets the text content of the accordion panel. */
+  async getText(): Promise<string> {
+    return (await this.host()).text();
+  }
+
+  /** Whether the accordion panel is expanded (visible and not inert). */
+  async isExpanded(): Promise<boolean> {
+    return (await (await this.host()).getAttribute('inert')) === null;
+  }
+}
+
+/** Harness for interacting with an `ngAccordionTrigger` in tests. */
+export class AccordionTriggerHarness extends ComponentHarness {
+  /** The selector for the host element of an `ngAccordionTrigger` instance. */
+  static hostSelector = '[ngAccordionTrigger]';
+
+  /**
+   * Gets a `HarnessPredicate` that can be used to search for a trigger with specific attributes.
+   * @param options Options for narrowing the search.
+   * @return a `HarnessPredicate` configured with the given options.
+   */
+  static with(
+    options: AccordionTriggerHarnessFilters = {},
+  ): HarnessPredicate<AccordionTriggerHarness> {
+    return new HarnessPredicate(AccordionTriggerHarness, options)
+      .addOption('text', options.text, (harness, text) =>
+        HarnessPredicate.stringMatches(harness.getText(), text),
+      )
+      .addOption(
+        'expanded',
+        options.expanded,
+        async (harness, expanded) => (await harness.isExpanded()) === expanded,
+      )
+      .addOption(
+        'disabled',
+        options.disabled,
+        async (harness, disabled) => (await harness.isDisabled()) === disabled,
+      );
+  }
+
+  /** Gets the text content of the accordion trigger. */
+  async getText(): Promise<string> {
+    return (await this.host()).text();
+  }
+
+  /** Clicks the accordion trigger. */
+  async click(): Promise<void> {
+    return (await this.host()).click();
+  }
+
+  /** Focuses the accordion trigger. */
+  async focus(): Promise<void> {
+    return (await this.host()).focus();
+  }
+
+  /** Blurs the accordion trigger. */
+  async blur(): Promise<void> {
+    return (await this.host()).blur();
+  }
+
+  /** Whether the accordion trigger is focused. */
+  async isFocused(): Promise<boolean> {
+    return (await this.host()).isFocused();
+  }
+
+  /** Whether the accordion panel associated with this trigger is expanded. */
+  async isExpanded(): Promise<boolean> {
+    const ariaExpanded = await (await this.host()).getAttribute('aria-expanded');
+    return ariaExpanded === 'true';
+  }
+
+  /** Whether the accordion trigger is disabled. */
+  async isDisabled(): Promise<boolean> {
+    const ariaDisabled = await (await this.host()).getAttribute('aria-disabled');
+    return ariaDisabled === 'true';
+  }
+}
+
+/** Harness for interacting with an `ngAccordionGroup` in tests. */
+export class AccordionGroupHarness extends ComponentHarness {
+  /** The selector for the host element of an `ngAccordionGroup` instance. */
+  static hostSelector = '[ngAccordionGroup]';
+
+  /**
+   * Gets a `HarnessPredicate` that can be used to search for an accordion group with specific attributes.
+   * @param options Options for narrowing the search.
+   * @return a `HarnessPredicate` configured with the given options.
+   */
+  static with(options: AccordionGroupHarnessFilters = {}): HarnessPredicate<AccordionGroupHarness> {
+    return new HarnessPredicate(AccordionGroupHarness, options);
+  }
+
+  /** Gets all accordion triggers within this group. */
+  async getTriggers(
+    filters: AccordionTriggerHarnessFilters = {},
+  ): Promise<AccordionTriggerHarness[]> {
+    return this.locatorForAll(AccordionTriggerHarness.with(filters))();
+  }
+
+  /** Gets all accordion panels within this group. */
+  async getPanels(filters: AccordionPanelHarnessFilters = {}): Promise<AccordionPanelHarness[]> {
+    return this.locatorForAll(AccordionPanelHarness.with(filters))();
+  }
+}
diff --git a/src/aria/accordion/testing/index.ts b/src/aria/accordion/testing/index.ts
new file mode 100644
index 000000000000..52b3c7a5156f
--- /dev/null
+++ b/src/aria/accordion/testing/index.ts
@@ -0,0 +1,9 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+export * from './public-api';
diff --git a/src/aria/accordion/testing/public-api.ts b/src/aria/accordion/testing/public-api.ts
new file mode 100644
index 000000000000..94d969f785aa
--- /dev/null
+++ b/src/aria/accordion/testing/public-api.ts
@@ -0,0 +1,9 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+export * from './accordion-harness';
diff --git a/src/aria/config.bzl b/src/aria/config.bzl
index 291412b5a3fb..de62934edcf6 100644
--- a/src/aria/config.bzl
+++ b/src/aria/config.bzl
@@ -1,6 +1,7 @@
 # List of all entry-points of the Angular Aria package.
 ARIA_ENTRYPOINTS = [
     "accordion",
+    "accordion/testing",
     "combobox",
     "grid",
     "listbox",

From 4972394c2692e7e7ab5e500e9130d78052e9e060 Mon Sep 17 00:00:00 2001
From: Cheng-Hsuan Tsai <webcat@google.com>
Date: Thu, 9 Apr 2026 20:59:24 +0000
Subject: [PATCH 2/4] refactor(aria/accordion): consolidate accordion harness
 to match material expansion harness

---
 .../testing/accordion-harness.spec.ts         | 142 +++++++++-------
 .../accordion/testing/accordion-harness.ts    | 153 ++++++++----------
 2 files changed, 149 insertions(+), 146 deletions(-)

diff --git a/src/aria/accordion/testing/accordion-harness.spec.ts b/src/aria/accordion/testing/accordion-harness.spec.ts
index a55768d4d383..cd43d4096b21 100644
--- a/src/aria/accordion/testing/accordion-harness.spec.ts
+++ b/src/aria/accordion/testing/accordion-harness.spec.ts
@@ -9,13 +9,19 @@
 import {Component} from '@angular/core';
 import {TestBed} from '@angular/core/testing';
 import {TestbedHarnessEnvironment} from '@angular/cdk/testing/testbed';
-import {
-  AccordionTriggerHarness,
-  AccordionPanelHarness,
-  AccordionGroupHarness,
-} from './accordion-harness';
+import {ComponentHarness} from '@angular/cdk/testing';
+import {AccordionHarness, AccordionGroupHarness} from './accordion-harness';
 import {AccordionGroup, AccordionPanel, AccordionTrigger} from '../index';
 
+/** Lightweight test harness to test querying inside the accordion body panel. */
+class TestButtonHarness extends ComponentHarness {
+  static hostSelector = 'button.test-button';
+
+  async getText(): Promise<string> {
+    return (await this.host()).text();
+  }
+}
+
 describe('Accordion Harnesses', () => {
   let fixture: any;
   let loader: any;
@@ -24,7 +30,9 @@ describe('Accordion Harnesses', () => {
     imports: [AccordionGroup, AccordionPanel, AccordionTrigger],
     template: `
       <div ngAccordionGroup>
-        <div #panel1="ngAccordionPanel" ngAccordionPanel>Content 1</div>
+        <div #panel1="ngAccordionPanel" ngAccordionPanel>
+          <button class="test-button">Inside Content 1</button>
+        </div>
         <button ngAccordionTrigger [panel]="panel1">Section 1</button>
 
         <div #panel2="ngAccordionPanel" ngAccordionPanel>Content 2</div>
@@ -43,82 +51,100 @@ describe('Accordion Harnesses', () => {
     loader = TestbedHarnessEnvironment.loader(fixture);
   });
 
-  it('should find all accordion triggers', async () => {
-    const triggers = await loader.getAllHarnesses(AccordionTriggerHarness);
-    expect(triggers.length).toBe(2);
+  it('should find accordion group and list all scoped accordions using getAccordions', async () => {
+    const group = await loader.getHarness(AccordionGroupHarness);
+    const accordions = await group.getAccordions();
+
+    expect(accordions.length).toBe(2);
+    expect(await accordions[0].getTitle()).toBe('Section 1');
+    expect(await accordions[1].getTitle()).toBe('Section 2');
   });
 
-  it('should support focusing and blurring accordion triggers', async () => {
-    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
-    await trigger.focus();
-    expect(await trigger.isFocused()).toBeTrue();
+  it('should find all individual accordions via standard root loader', async () => {
+    const accordions = await loader.getAllHarnesses(AccordionHarness);
+    expect(accordions.length).toBe(2);
+  });
 
-    await trigger.blur();
-    expect(await trigger.isFocused()).toBeFalse();
+  it('should filter accordions by title', async () => {
+    const accordions = await loader.getAllHarnesses(AccordionHarness.with({title: 'Section 1'}));
+    expect(accordions.length).toBe(1);
+    expect(await accordions[0].getTitle()).toBe('Section 1');
   });
 
-  it('should correctly report the disabled state of a trigger', async () => {
-    const activeTrigger = await loader.getHarness(
-      AccordionTriggerHarness.with({text: 'Section 1'}),
-    );
-    const disabledTrigger = await loader.getHarness(
-      AccordionTriggerHarness.with({text: 'Section 2'}),
+  it('should filter accordions by expanded state', async () => {
+    const accordion = await loader.getHarness(AccordionHarness.with({title: 'Section 1'}));
+    await accordion.expand();
+
+    const expandedAccordions = await loader.getAllHarnesses(
+      AccordionHarness.with({expanded: true}),
     );
+    expect(expandedAccordions.length).toBe(1);
+    expect(await expandedAccordions[0].getTitle()).toBe('Section 1');
+  });
 
-    expect(await activeTrigger.isDisabled()).toBeFalse();
-    expect(await disabledTrigger.isDisabled()).toBeTrue();
+  it('should filter accordions by disabled state', async () => {
+    const disabledAccordions = await loader.getAllHarnesses(
+      AccordionHarness.with({disabled: true}),
+    );
+    expect(disabledAccordions.length).toBe(1);
+    expect(await disabledAccordions[0].getTitle()).toBe('Section 2');
   });
 
-  it('should correctly report the expanded state of a trigger', async () => {
-    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
-    expect(await trigger.isExpanded()).toBeFalse();
+  it('should get the title of the accordion', async () => {
+    const accordion = await loader.getHarness(AccordionHarness.with({title: 'Section 1'}));
+    expect(await accordion.getTitle()).toBe('Section 1');
+  });
 
-    await trigger.click();
-    expect(await trigger.isExpanded()).toBeTrue();
+  it('should correctly report the expanded state of an accordion', async () => {
+    const accordion = await loader.getHarness(AccordionHarness.with({title: 'Section 1'}));
+    expect(await accordion.isExpanded()).toBeFalse();
   });
 
-  it('should filter triggers by disabled state', async () => {
-    const disabledTriggers = await loader.getAllHarnesses(
-      AccordionTriggerHarness.with({disabled: true}),
-    );
-    expect(disabledTriggers.length).toBe(1);
-    expect(await disabledTriggers[0].getText()).toBe('Section 2');
+  it('should correctly report the disabled state of an accordion', async () => {
+    const activeAccordion = await loader.getHarness(AccordionHarness.with({title: 'Section 1'}));
+    const disabledAccordion = await loader.getHarness(AccordionHarness.with({title: 'Section 2'}));
+
+    expect(await activeAccordion.isDisabled()).toBeFalse();
+    expect(await disabledAccordion.isDisabled()).toBeTrue();
   });
 
-  it('should filter triggers by expanded state', async () => {
-    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
-    await trigger.click();
+  it('expands a collapsed accordion using the expand method', async () => {
+    const accordion = await loader.getHarness(AccordionHarness.with({title: 'Section 1'}));
 
-    const expandedTriggers = await loader.getAllHarnesses(
-      AccordionTriggerHarness.with({expanded: true}),
-    );
-    expect(expandedTriggers.length).toBe(1);
-    expect(await expandedTriggers[0].getText()).toBe('Section 1');
+    await accordion.expand();
+
+    expect(await accordion.isExpanded()).toBeTrue();
   });
 
-  it('should find the panel associated with a specific trigger', async () => {
-    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
-    const panel = await loader.getHarness(AccordionPanelHarness.with({trigger}));
+  it('collapses an expanded accordion using the collapse method', async () => {
+    const accordion = await loader.getHarness(AccordionHarness.with({title: 'Section 1'}));
+    await accordion.expand();
 
-    expect(await panel.getText()).toBe('Content 1');
+    await accordion.collapse();
+
+    expect(await accordion.isExpanded()).toBeFalse();
   });
 
-  it('should correctly report the expanded state of an accordion panel', async () => {
-    const trigger = await loader.getHarness(AccordionTriggerHarness.with({text: 'Section 1'}));
-    const panel = await loader.getHarness(AccordionPanelHarness.with({trigger}));
+  it('toggles the expanded state of an accordion using the toggle method', async () => {
+    const accordion = await loader.getHarness(AccordionHarness.with({title: 'Section 1'}));
 
-    expect(await panel.isExpanded()).toBeFalse();
+    await accordion.toggle();
 
-    await trigger.click();
-    expect(await panel.isExpanded()).toBeTrue();
+    expect(await accordion.isExpanded()).toBeTrue();
   });
 
-  it('should find accordion group and list scoped triggers and panels', async () => {
-    const group = await loader.getHarness(AccordionGroupHarness);
-    const triggers = await group.getTriggers();
-    const panels = await group.getPanels();
+  it('should support focusing and blurring accordion triggers', async () => {
+    const accordion = await loader.getHarness(AccordionHarness.with({title: 'Section 1'}));
+    await accordion.focus();
+    expect(await accordion.isFocused()).toBeTrue();
+
+    await accordion.blur();
+    expect(await accordion.isFocused()).toBeFalse();
+  });
 
-    expect(triggers.length).toBe(2);
-    expect(panels.length).toBe(2);
+  it('should query components inside the accordion panel using ContentContainerComponentHarness', async () => {
+    const accordion = await loader.getHarness(AccordionHarness.with({title: 'Section 1'}));
+    const button = await accordion.getHarness(TestButtonHarness);
+    expect(await button.getText()).toBe('Inside Content 1');
   });
 });
diff --git a/src/aria/accordion/testing/accordion-harness.ts b/src/aria/accordion/testing/accordion-harness.ts
index 1b8fdfcdd0b9..0a401fa8f505 100644
--- a/src/aria/accordion/testing/accordion-harness.ts
+++ b/src/aria/accordion/testing/accordion-harness.ts
@@ -6,76 +6,44 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
-import {ComponentHarness, HarnessPredicate, BaseHarnessFilters} from '@angular/cdk/testing';
+import {
+  ComponentHarness,
+  ContentContainerComponentHarness,
+  HarnessPredicate,
+  BaseHarnessFilters,
+} from '@angular/cdk/testing';
+
+/** Selectors for the sections that may contain user content. */
+export enum AccordionSection {
+  TRIGGER = '[ngAccordionTrigger]',
+  PANEL = '[ngAccordionPanel]',
+}
 
-/** Filters for locating an `AccordionTriggerHarness`. */
-export interface AccordionTriggerHarnessFilters extends BaseHarnessFilters {
-  /** Only find instances whose text matches the given value. */
-  text?: string | RegExp;
+/** Filters for locating an `AccordionHarness`. */
+export interface AccordionHarnessFilters extends BaseHarnessFilters {
+  /** Only find instances whose title text matches the given value. */
+  title?: string | RegExp;
   /** Only find instances whose expanded state matches the given value. */
   expanded?: boolean;
   /** Only find instances whose disabled state matches the given value. */
   disabled?: boolean;
 }
 
-/** Filters for locating an `AccordionPanelHarness`. */
-export interface AccordionPanelHarnessFilters extends BaseHarnessFilters {
-  /** Find the panel associated with the given trigger harness. */
-  trigger?: AccordionTriggerHarness;
-}
-
 /** Filters for locating an `AccordionGroupHarness`. */
 export interface AccordionGroupHarnessFilters extends BaseHarnessFilters {}
 
-/** Harness for interacting with an `ngAccordionPanel` in tests. */
-export class AccordionPanelHarness extends ComponentHarness {
-  /** The selector for the host element of an `ngAccordionPanel` instance. */
-  static hostSelector = '[ngAccordionPanel]';
-
-  /**
-   * Gets a `HarnessPredicate` that can be used to search for a panel with specific attributes.
-   * @param options Options for narrowing the search.
-   * @return a `HarnessPredicate` configured with the given options.
-   */
-  static with(options: AccordionPanelHarnessFilters = {}): HarnessPredicate<AccordionPanelHarness> {
-    return new HarnessPredicate(AccordionPanelHarness, options).addOption(
-      'trigger',
-      options.trigger,
-      async (harness, trigger) => {
-        const targetPanelId = await (await trigger.host()).getAttribute('aria-controls');
-        const panelId = await (await harness.host()).getAttribute('id');
-        return panelId === targetPanelId;
-      },
-    );
-  }
-
-  /** Gets the text content of the accordion panel. */
-  async getText(): Promise<string> {
-    return (await this.host()).text();
-  }
-
-  /** Whether the accordion panel is expanded (visible and not inert). */
-  async isExpanded(): Promise<boolean> {
-    return (await (await this.host()).getAttribute('inert')) === null;
-  }
-}
-
-/** Harness for interacting with an `ngAccordionTrigger` in tests. */
-export class AccordionTriggerHarness extends ComponentHarness {
-  /** The selector for the host element of an `ngAccordionTrigger` instance. */
+/** Harness for interacting with a standard ngAccordion item in tests. */
+export class AccordionHarness extends ContentContainerComponentHarness<AccordionSection> {
   static hostSelector = '[ngAccordionTrigger]';
 
   /**
-   * Gets a `HarnessPredicate` that can be used to search for a trigger with specific attributes.
-   * @param options Options for narrowing the search.
-   * @return a `HarnessPredicate` configured with the given options.
+   * Gets a `HarnessPredicate` that can be used to search for an accordion
+   * with specific attributes.
    */
-  static with(
-    options: AccordionTriggerHarnessFilters = {},
-  ): HarnessPredicate<AccordionTriggerHarness> {
-    return new HarnessPredicate(AccordionTriggerHarness, options)
-      .addOption('text', options.text, (harness, text) =>
-        HarnessPredicate.stringMatches(harness.getText(), text),
+  static with(options: AccordionHarnessFilters = {}): HarnessPredicate<AccordionHarness> {
+    return new HarnessPredicate(AccordionHarness, options)
+      .addOption('title', options.title, (harness, title) =>
+        HarnessPredicate.stringMatches(harness.getTitle(), title),
       )
       .addOption(
         'expanded',
@@ -89,67 +57,76 @@ export class AccordionTriggerHarness extends ComponentHarness {
       );
   }
 
-  /** Gets the text content of the accordion trigger. */
-  async getText(): Promise<string> {
+  /** Overrides the internal loader to automatically resolve queries inside the associated panel. */
+  protected override async getRootHarnessLoader() {
+    const panelId = await (await this.host()).getAttribute('aria-controls');
+    const documentRoot = await this.documentRootLocatorFactory().rootHarnessLoader();
+    return documentRoot.getChildLoader(`[ngAccordionPanel][id="${panelId}"]`);
+  }
+
+  /** Whether the accordion is expanded. */
+  async isExpanded(): Promise<boolean> {
+    return (await (await this.host()).getAttribute('aria-expanded')) === 'true';
+  }
+
+  /** Whether the accordion is disabled. */
+  async isDisabled(): Promise<boolean> {
+    return (await (await this.host()).getAttribute('aria-disabled')) === 'true';
+  }
+
+  /** Gets the title text of the accordion. */
+  async getTitle(): Promise<string> {
     return (await this.host()).text();
   }
 
-  /** Clicks the accordion trigger. */
-  async click(): Promise<void> {
-    return (await this.host()).click();
+  /** Toggles the expanded state of the accordion by clicking on the trigger. */
+  async toggle(): Promise<void> {
+    await (await this.host()).click();
+  }
+
+  /** Expands the accordion if collapsed. */
+  async expand(): Promise<void> {
+    if (!(await this.isExpanded())) {
+      await this.toggle();
+    }
+  }
+
+  /** Collapses the accordion if expanded. */
+  async collapse(): Promise<void> {
+    if (await this.isExpanded()) {
+      await this.toggle();
+    }
   }
 
   /** Focuses the accordion trigger. */
   async focus(): Promise<void> {
-    return (await this.host()).focus();
+    await (await this.host()).focus();
   }
 
   /** Blurs the accordion trigger. */
   async blur(): Promise<void> {
-    return (await this.host()).blur();
+    await (await this.host()).blur();
   }
 
   /** Whether the accordion trigger is focused. */
   async isFocused(): Promise<boolean> {
     return (await this.host()).isFocused();
   }
-
-  /** Whether the accordion panel associated with this trigger is expanded. */
-  async isExpanded(): Promise<boolean> {
-    const ariaExpanded = await (await this.host()).getAttribute('aria-expanded');
-    return ariaExpanded === 'true';
-  }
-
-  /** Whether the accordion trigger is disabled. */
-  async isDisabled(): Promise<boolean> {
-    const ariaDisabled = await (await this.host()).getAttribute('aria-disabled');
-    return ariaDisabled === 'true';
-  }
 }
 
 /** Harness for interacting with an `ngAccordionGroup` in tests. */
 export class AccordionGroupHarness extends ComponentHarness {
-  /** The selector for the host element of an `ngAccordionGroup` instance. */
   static hostSelector = '[ngAccordionGroup]';
 
   /**
    * Gets a `HarnessPredicate` that can be used to search for an accordion group with specific attributes.
-   * @param options Options for narrowing the search.
-   * @return a `HarnessPredicate` configured with the given options.
    */
   static with(options: AccordionGroupHarnessFilters = {}): HarnessPredicate<AccordionGroupHarness> {
     return new HarnessPredicate(AccordionGroupHarness, options);
   }
 
-  /** Gets all accordion triggers within this group. */
-  async getTriggers(
-    filters: AccordionTriggerHarnessFilters = {},
-  ): Promise<AccordionTriggerHarness[]> {
-    return this.locatorForAll(AccordionTriggerHarness.with(filters))();
-  }
-
-  /** Gets all accordion panels within this group. */
-  async getPanels(filters: AccordionPanelHarnessFilters = {}): Promise<AccordionPanelHarness[]> {
-    return this.locatorForAll(AccordionPanelHarness.with(filters))();
+  /** Gets all accordions within this group. */
+  async getAccordions(filters: AccordionHarnessFilters = {}): Promise<AccordionHarness[]> {
+    return this.locatorForAll(AccordionHarness.with(filters))();
   }
 }

From 6a16ffabcaa1e77208a025680839f5cab880d9bb Mon Sep 17 00:00:00 2001
From: Cheng-Hsuan Tsai <webcat@google.com>
Date: Thu, 9 Apr 2026 21:12:50 +0000
Subject: [PATCH 3/4] fixup! refactor(aria/accordion): consolidate accordion
 harness to match material expansion harness

---
 goldens/aria/accordion/testing/index.api.md | 43 +++++++++++----------
 1 file changed, 22 insertions(+), 21 deletions(-)

diff --git a/goldens/aria/accordion/testing/index.api.md b/goldens/aria/accordion/testing/index.api.md
index 8e7cbe63088d..ef4d0432fa9a 100644
--- a/goldens/aria/accordion/testing/index.api.md
+++ b/goldens/aria/accordion/testing/index.api.md
@@ -4,14 +4,16 @@
 
 ```ts
 
+import * as _angular_cdk_testing from '@angular/cdk/testing';
 import { BaseHarnessFilters } from '@angular/cdk/testing';
 import { ComponentHarness } from '@angular/cdk/testing';
+import { ContentContainerComponentHarness } from '@angular/cdk/testing';
 import { HarnessPredicate } from '@angular/cdk/testing';
 
 // @public
 export class AccordionGroupHarness extends ComponentHarness {
-    getPanels(filters?: AccordionPanelHarnessFilters): Promise<AccordionPanelHarness[]>;
-    getTriggers(filters?: AccordionTriggerHarnessFilters): Promise<AccordionTriggerHarness[]>;
+    getAccordions(filters?: AccordionHarnessFilters): Promise<AccordionHarness[]>;
+    // (undocumented)
     static hostSelector: string;
     static with(options?: AccordionGroupHarnessFilters): HarnessPredicate<AccordionGroupHarness>;
 }
@@ -21,36 +23,35 @@ export interface AccordionGroupHarnessFilters extends BaseHarnessFilters {
 }
 
 // @public
-export class AccordionPanelHarness extends ComponentHarness {
-    getText(): Promise<string>;
-    static hostSelector: string;
-    isExpanded(): Promise<boolean>;
-    static with(options?: AccordionPanelHarnessFilters): HarnessPredicate<AccordionPanelHarness>;
-}
-
-// @public
-export interface AccordionPanelHarnessFilters extends BaseHarnessFilters {
-    trigger?: AccordionTriggerHarness;
-}
-
-// @public
-export class AccordionTriggerHarness extends ComponentHarness {
+export class AccordionHarness extends ContentContainerComponentHarness<AccordionSection> {
     blur(): Promise<void>;
-    click(): Promise<void>;
+    collapse(): Promise<void>;
+    expand(): Promise<void>;
     focus(): Promise<void>;
-    getText(): Promise<string>;
+    protected getRootHarnessLoader(): Promise<_angular_cdk_testing.HarnessLoader>;
+    getTitle(): Promise<string>;
+    // (undocumented)
     static hostSelector: string;
     isDisabled(): Promise<boolean>;
     isExpanded(): Promise<boolean>;
     isFocused(): Promise<boolean>;
-    static with(options?: AccordionTriggerHarnessFilters): HarnessPredicate<AccordionTriggerHarness>;
+    toggle(): Promise<void>;
+    static with(options?: AccordionHarnessFilters): HarnessPredicate<AccordionHarness>;
 }
 
 // @public
-export interface AccordionTriggerHarnessFilters extends BaseHarnessFilters {
+export interface AccordionHarnessFilters extends BaseHarnessFilters {
     disabled?: boolean;
     expanded?: boolean;
-    text?: string | RegExp;
+    title?: string | RegExp;
+}
+
+// @public
+export enum AccordionSection {
+    // (undocumented)
+    PANEL = "[ngAccordionPanel]",
+    // (undocumented)
+    TRIGGER = "[ngAccordionTrigger]"
 }
 
 // (No @packageDocumentation comment for this package)

From 84ac04703e3cd970bee809a6871dd296272d1faa Mon Sep 17 00:00:00 2001
From: Cheng-Hsuan Tsai <webcat@google.com>
Date: Fri, 10 Apr 2026 06:03:22 +0000
Subject: [PATCH 4/4] fixup! refactor(aria/accordion): consolidate accordion
 harness to match material expansion harness

---
 .../testing/accordion-harness-filters.ts      | 22 +++++++++++++++++++
 .../accordion/testing/accordion-harness.ts    | 15 +------------
 src/aria/accordion/testing/public-api.ts      |  1 +
 3 files changed, 24 insertions(+), 14 deletions(-)
 create mode 100644 src/aria/accordion/testing/accordion-harness-filters.ts

diff --git a/src/aria/accordion/testing/accordion-harness-filters.ts b/src/aria/accordion/testing/accordion-harness-filters.ts
new file mode 100644
index 000000000000..7c736ddb1c51
--- /dev/null
+++ b/src/aria/accordion/testing/accordion-harness-filters.ts
@@ -0,0 +1,22 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import {BaseHarnessFilters} from '@angular/cdk/testing';
+
+/** Filters for locating an `AccordionHarness`. */
+export interface AccordionHarnessFilters extends BaseHarnessFilters {
+  /** Only find instances whose title text matches the given value. */
+  title?: string | RegExp;
+  /** Only find instances whose expanded state matches the given value. */
+  expanded?: boolean;
+  /** Only find instances whose disabled state matches the given value. */
+  disabled?: boolean;
+}
+
+/** Filters for locating an `AccordionGroupHarness`. */
+export interface AccordionGroupHarnessFilters extends BaseHarnessFilters {}
diff --git a/src/aria/accordion/testing/accordion-harness.ts b/src/aria/accordion/testing/accordion-harness.ts
index 0a401fa8f505..d37c40bdac01 100644
--- a/src/aria/accordion/testing/accordion-harness.ts
+++ b/src/aria/accordion/testing/accordion-harness.ts
@@ -10,8 +10,8 @@ import {
   ComponentHarness,
   ContentContainerComponentHarness,
   HarnessPredicate,
-  BaseHarnessFilters,
 } from '@angular/cdk/testing';
+import {AccordionHarnessFilters, AccordionGroupHarnessFilters} from './accordion-harness-filters';
 
 /** Selectors for the sections that may contain user content. */
 export enum AccordionSection {
@@ -19,19 +19,6 @@ export enum AccordionSection {
   PANEL = '[ngAccordionPanel]',
 }
 
-/** Filters for locating an `AccordionHarness`. */
-export interface AccordionHarnessFilters extends BaseHarnessFilters {
-  /** Only find instances whose title text matches the given value. */
-  title?: string | RegExp;
-  /** Only find instances whose expanded state matches the given value. */
-  expanded?: boolean;
-  /** Only find instances whose disabled state matches the given value. */
-  disabled?: boolean;
-}
-
-/** Filters for locating an `AccordionGroupHarness`. */
-export interface AccordionGroupHarnessFilters extends BaseHarnessFilters {}
-
 /** Harness for interacting with a standard ngAccordion item in tests. */
 export class AccordionHarness extends ContentContainerComponentHarness<AccordionSection> {
   static hostSelector = '[ngAccordionTrigger]';
diff --git a/src/aria/accordion/testing/public-api.ts b/src/aria/accordion/testing/public-api.ts
index 94d969f785aa..acb15bdb15bd 100644
--- a/src/aria/accordion/testing/public-api.ts
+++ b/src/aria/accordion/testing/public-api.ts
@@ -7,3 +7,4 @@
  */
 
 export * from './accordion-harness';
+export * from './accordion-harness-filters';