diff --git a/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/BUILD.bazel b/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/BUILD.bazel
index 47e1acdb8bd..b036f7e133b 100644
--- a/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/BUILD.bazel
+++ b/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/BUILD.bazel
@@ -19,7 +19,7 @@ ng_project(
 
 ts_test_library(
     name = "ng-debug-api_test_lib",
-    srcs = ["ng-debug-api.spec.ts"],
+    srcs = glob(["*.spec.ts"]),
     deps = [
         ":ng-debug-api",
         "//:node_modules/@angular/core",
diff --git a/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/ng-debug-api.spec.ts b/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/ng-debug-api.spec.ts
index e5f723c3ad8..d8169075b9d 100644
--- a/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/ng-debug-api.spec.ts
+++ b/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/ng-debug-api.spec.ts
@@ -61,6 +61,7 @@ const fakeNgGlobal = (framework: Framework): Partial<Ng> => {
 describe('ng-debug-api', () => {
   afterEach(() => {
     delete (globalThis as any).ng;
+    document.body.replaceChildren();
   });
 
   describe('ngDebugDependencyInjectionApiIsSupported', () => {
diff --git a/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/supported-apis.spec.ts b/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/supported-apis.spec.ts
index c6a5889b238..29ed9c0b27b 100644
--- a/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/supported-apis.spec.ts
+++ b/devtools/projects/ng-devtools-backend/src/lib/shared/ng-debug-api/supported-apis.spec.ts
@@ -9,11 +9,38 @@
 import {getSupportedApis} from './supported-apis';
 
 describe('supported-apis', () => {
+  afterEach(() => {
+    delete (globalThis as any).ng;
+  });
+
   describe('getSupportedApis', () => {
-    it('should return supported APIs', () => {
+    it('should return every flag as false when no debug API is available', () => {
+      (globalThis as any).ng = {};
+
       const supported = getSupportedApis();
 
-      expect(supported).toBeTruthy();
+      expect(Object.keys(supported).sort()).toEqual([
+        'dependencyInjection',
+        'profiler',
+        'routes',
+        'signalPropertiesInspection',
+        'signals',
+        'transferState',
+      ]);
+      expect(Object.values(supported).every((value) => value === false)).toBeTrue();
+    });
+
+    it('should only report signals when the signal graph API is available', () => {
+      (globalThis as any).ng = {ɵgetSignalGraph: () => {}};
+
+      const supported = getSupportedApis();
+
+      expect(supported.signals).toBeTrue();
+      expect(supported.dependencyInjection).toBeFalse();
+      expect(supported.profiler).toBeFalse();
+      expect(supported.routes).toBeFalse();
+      expect(supported.signalPropertiesInspection).toBeFalse();
+      expect(supported.transferState).toBeFalse();
     });
   });
 });