diff --git a/src/cdk/testing/component-harness.ts b/src/cdk/testing/component-harness.ts
index 455fd5fdd54b..72e914558545 100644
--- a/src/cdk/testing/component-harness.ts
+++ b/src/cdk/testing/component-harness.ts
@@ -137,8 +137,8 @@ export interface LocatorFactory {
    * - `await lf.locatorFor('div', DivHarness)()` gets a `TestElement` instance for `#d1`
    * - `await lf.locatorFor('span')()` throws because the `Promise` rejects.
    */
-  locatorFor<T extends (HarnessQuery<any> | string)[]>(...queries: T):
-      AsyncFactoryFn<LocatorFnResult<T>>;
+  locatorFor<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]):
+      AsyncFactoryFn<LocatorFnResult<T[]>>;
 
   /**
    * Creates an asynchronous locator function that can be used to find a `ComponentHarness` instance
@@ -161,8 +161,8 @@ export interface LocatorFactory {
    * - `await lf.locatorForOptional('div', DivHarness)()` gets a `TestElement` instance for `#d1`
    * - `await lf.locatorForOptional('span')()` gets `null`.
    */
-  locatorForOptional<T extends (HarnessQuery<any> | string)[]>(...queries: T):
-      AsyncFactoryFn<LocatorFnResult<T> | null>;
+  locatorForOptional<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]):
+      AsyncFactoryFn<LocatorFnResult<T[]> | null>;
 
   /**
    * Creates an asynchronous locator function that can be used to find `ComponentHarness` instances
@@ -200,8 +200,8 @@ export interface LocatorFactory {
    *   ]`
    * - `await lf.locatorForAll('span')()` gets `[]`.
    */
-  locatorForAll<T extends (HarnessQuery<any> | string)[]>(...queries: T):
-      AsyncFactoryFn<LocatorFnResult<T>[]>;
+  locatorForAll<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]):
+      AsyncFactoryFn<LocatorFnResult<T[]>[]>;
 
   /** @return A `HarnessLoader` rooted at the root element of this `LocatorFactory`. */
   rootHarnessLoader(): Promise<HarnessLoader>;
@@ -286,8 +286,8 @@ export abstract class ComponentHarness {
    * - `await ch.locatorFor('div', DivHarness)()` gets a `TestElement` instance for `#d1`
    * - `await ch.locatorFor('span')()` throws because the `Promise` rejects.
    */
-  protected locatorFor<T extends (HarnessQuery<any> | string)[]>(...queries: T):
-      AsyncFactoryFn<LocatorFnResult<T>> {
+  protected locatorFor<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]):
+      AsyncFactoryFn<LocatorFnResult<T[]>> {
     return this.locatorFactory.locatorFor(...queries);
   }
 
@@ -312,8 +312,8 @@ export abstract class ComponentHarness {
    * - `await ch.locatorForOptional('div', DivHarness)()` gets a `TestElement` instance for `#d1`
    * - `await ch.locatorForOptional('span')()` gets `null`.
    */
-  protected locatorForOptional<T extends (HarnessQuery<any> | string)[]>(...queries: T):
-      AsyncFactoryFn<LocatorFnResult<T> | null> {
+  protected locatorForOptional<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]):
+      AsyncFactoryFn<LocatorFnResult<T[]> | null> {
     return this.locatorFactory.locatorForOptional(...queries);
   }
 
@@ -353,8 +353,8 @@ export abstract class ComponentHarness {
    *   ]`
    * - `await ch.locatorForAll('span')()` gets `[]`.
    */
-  protected locatorForAll<T extends (HarnessQuery<any> | string)[]>(...queries: T):
-      AsyncFactoryFn<LocatorFnResult<T>[]> {
+  protected locatorForAll<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]):
+      AsyncFactoryFn<LocatorFnResult<T[]>[]> {
     return this.locatorFactory.locatorForAll(...queries);
   }
 
diff --git a/src/cdk/testing/harness-environment.ts b/src/cdk/testing/harness-environment.ts
index 96aea98a417e..c11276289aff 100644
--- a/src/cdk/testing/harness-environment.ts
+++ b/src/cdk/testing/harness-environment.ts
@@ -57,22 +57,22 @@ export abstract class HarnessEnvironment<E> implements HarnessLoader, LocatorFac
   }
 
   // Implemented as part of the `LocatorFactory` interface.
-  locatorFor<T extends (HarnessQuery<any> | string)[]>(...queries: T):
-      AsyncFactoryFn<LocatorFnResult<T>> {
+  locatorFor<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]):
+      AsyncFactoryFn<LocatorFnResult<T[]>> {
     return () => _assertResultFound(
         this._getAllHarnessesAndTestElements(queries),
         _getDescriptionForLocatorForQueries(queries));
   }
 
   // Implemented as part of the `LocatorFactory` interface.
-  locatorForOptional<T extends (HarnessQuery<any> | string)[]>(...queries: T):
-      AsyncFactoryFn<LocatorFnResult<T> | null> {
+  locatorForOptional<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]):
+      AsyncFactoryFn<LocatorFnResult<T[]> | null> {
     return async () => (await this._getAllHarnessesAndTestElements(queries))[0] || null;
   }
 
   // Implemented as part of the `LocatorFactory` interface.
-  locatorForAll<T extends (HarnessQuery<any> | string)[]>(...queries: T):
-      AsyncFactoryFn<LocatorFnResult<T>[]> {
+  locatorForAll<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]):
+      AsyncFactoryFn<LocatorFnResult<T[]>[]> {
     return () => this._getAllHarnessesAndTestElements(queries);
   }
 
diff --git a/tools/public_api_guard/cdk/testing.md b/tools/public_api_guard/cdk/testing.md
index 954a3e4de266..25ee234ba56b 100644
--- a/tools/public_api_guard/cdk/testing.md
+++ b/tools/public_api_guard/cdk/testing.md
@@ -33,9 +33,9 @@ export abstract class ComponentHarness {
     host(): Promise<TestElement>;
     // (undocumented)
     protected readonly locatorFactory: LocatorFactory;
-    protected locatorFor<T extends (HarnessQuery<any> | string)[]>(...queries: T): AsyncFactoryFn<LocatorFnResult<T>>;
-    protected locatorForAll<T extends (HarnessQuery<any> | string)[]>(...queries: T): AsyncFactoryFn<LocatorFnResult<T>[]>;
-    protected locatorForOptional<T extends (HarnessQuery<any> | string)[]>(...queries: T): AsyncFactoryFn<LocatorFnResult<T> | null>;
+    protected locatorFor<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]): AsyncFactoryFn<LocatorFnResult<T[]>>;
+    protected locatorForAll<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]): AsyncFactoryFn<LocatorFnResult<T[]>[]>;
+    protected locatorForOptional<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]): AsyncFactoryFn<LocatorFnResult<T[]> | null>;
     protected waitForTasksOutsideAngular(): Promise<void>;
 }
 
@@ -109,11 +109,11 @@ export abstract class HarnessEnvironment<E> implements HarnessLoader, LocatorFac
     // (undocumented)
     harnessLoaderForOptional(selector: string): Promise<HarnessLoader | null>;
     // (undocumented)
-    locatorFor<T extends (HarnessQuery<any> | string)[]>(...queries: T): AsyncFactoryFn<LocatorFnResult<T>>;
+    locatorFor<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]): AsyncFactoryFn<LocatorFnResult<T[]>>;
     // (undocumented)
-    locatorForAll<T extends (HarnessQuery<any> | string)[]>(...queries: T): AsyncFactoryFn<LocatorFnResult<T>[]>;
+    locatorForAll<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]): AsyncFactoryFn<LocatorFnResult<T[]>[]>;
     // (undocumented)
-    locatorForOptional<T extends (HarnessQuery<any> | string)[]>(...queries: T): AsyncFactoryFn<LocatorFnResult<T> | null>;
+    locatorForOptional<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]): AsyncFactoryFn<LocatorFnResult<T[]> | null>;
     // (undocumented)
     protected rawRootElement: E;
     // (undocumented)
@@ -156,9 +156,9 @@ export interface LocatorFactory {
     harnessLoaderFor(selector: string): Promise<HarnessLoader>;
     harnessLoaderForAll(selector: string): Promise<HarnessLoader[]>;
     harnessLoaderForOptional(selector: string): Promise<HarnessLoader | null>;
-    locatorFor<T extends (HarnessQuery<any> | string)[]>(...queries: T): AsyncFactoryFn<LocatorFnResult<T>>;
-    locatorForAll<T extends (HarnessQuery<any> | string)[]>(...queries: T): AsyncFactoryFn<LocatorFnResult<T>[]>;
-    locatorForOptional<T extends (HarnessQuery<any> | string)[]>(...queries: T): AsyncFactoryFn<LocatorFnResult<T> | null>;
+    locatorFor<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]): AsyncFactoryFn<LocatorFnResult<T[]>>;
+    locatorForAll<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]): AsyncFactoryFn<LocatorFnResult<T[]>[]>;
+    locatorForOptional<T extends (HarnessQuery<any> | string)>(...queries: [T, ...T[]]): AsyncFactoryFn<LocatorFnResult<T[]> | null>;
     rootElement: TestElement;
     rootHarnessLoader(): Promise<HarnessLoader>;
     waitForTasksOutsideAngular(): Promise<void>;