diff --git a/devtools/client/debugger/src/actions/ast/tests/setInScopeLines.spec.js b/devtools/client/debugger/src/actions/ast/tests/setInScopeLines.spec.js
index 5d96cba08875..4b1182303099 100644
--- a/devtools/client/debugger/src/actions/ast/tests/setInScopeLines.spec.js
+++ b/devtools/client/debugger/src/actions/ast/tests/setInScopeLines.spec.js
@@ -21,7 +21,7 @@ const sourceTexts = {
   "scopes.js": readFixture("scopes.js"),
 };
 
-const threadFront = {
+const mockCommandClient = {
   sourceContents: async ({ source }) => ({
     source: sourceTexts[source],
     contentType: "text/javascript",
@@ -34,7 +34,7 @@ const threadFront = {
 
 describe("getInScopeLine", () => {
   it("with selected line", async () => {
-    const store = createStore(threadFront);
+    const store = createStore(mockCommandClient);
     const { dispatch, getState } = store;
     const source = makeMockSource("scopes.js", "scopes.js");
 
diff --git a/devtools/client/debugger/src/actions/breakpoints/tests/breakpointPositions.spec.js b/devtools/client/debugger/src/actions/breakpoints/tests/breakpointPositions.spec.js
index d925c40f95ad..b4f049ad18ca 100644
--- a/devtools/client/debugger/src/actions/breakpoints/tests/breakpointPositions.spec.js
+++ b/devtools/client/debugger/src/actions/breakpoints/tests/breakpointPositions.spec.js
@@ -11,7 +11,7 @@ import {
   makeSource,
   waitForState,
 } from "../../../utils/test-head";
-import { createSource } from "../../tests/helpers/threadFront";
+import { createSource } from "../../tests/helpers/mockCommandClient";
 
 describe("breakpointPositions", () => {
   it("fetches positions", async () => {
diff --git a/devtools/client/debugger/src/actions/breakpoints/tests/breakpoints.spec.js b/devtools/client/debugger/src/actions/breakpoints/tests/breakpoints.spec.js
index b14fa1c3f4af..ae7eeb30f8cd 100644
--- a/devtools/client/debugger/src/actions/breakpoints/tests/breakpoints.spec.js
+++ b/devtools/client/debugger/src/actions/breakpoints/tests/breakpoints.spec.js
@@ -12,11 +12,11 @@ import {
   getTelemetryEvents,
 } from "../../../utils/test-head";
 
-import { simpleMockThreadFront } from "../../tests/helpers/threadFront.js";
+import { mockCommandClient } from "../../tests/helpers/mockCommandClient";
 
 function mockClient(positionsResponse = {}) {
   return {
-    ...simpleMockThreadFront,
+    ...mockCommandClient,
     getBreakpointPositions: async () => positionsResponse,
     getBreakableLines: async () => [],
   };
diff --git a/devtools/client/debugger/src/actions/pause/tests/pause.spec.js b/devtools/client/debugger/src/actions/pause/tests/pause.spec.js
index f60d137d4035..c0bd32823712 100644
--- a/devtools/client/debugger/src/actions/pause/tests/pause.spec.js
+++ b/devtools/client/debugger/src/actions/pause/tests/pause.spec.js
@@ -22,7 +22,7 @@ import { features } from "../../../utils/prefs";
 const { isStepping } = selectors;
 
 let stepInResolve = null;
-const mockThreadFront = {
+const mockCommandClient = {
   stepIn: () =>
     new Promise(_resolve => {
       stepInResolve = _resolve;
@@ -104,7 +104,7 @@ function createPauseInfo(
 describe("pause", () => {
   describe("stepping", () => {
     it("should set and clear the command", async () => {
-      const { dispatch, getState } = createStore(mockThreadFront);
+      const { dispatch, getState } = createStore(mockCommandClient);
       const mockPauseInfo = createPauseInfo();
 
       await dispatch(actions.newGeneratedSource(makeSource("foo1")));
@@ -129,7 +129,7 @@ describe("pause", () => {
     });
 
     it("should step when paused", async () => {
-      const { dispatch, getState } = createStore(mockThreadFront);
+      const { dispatch, getState } = createStore(mockCommandClient);
       const mockPauseInfo = createPauseInfo();
 
       await dispatch(actions.newGeneratedSource(makeSource("foo1")));
@@ -140,7 +140,7 @@ describe("pause", () => {
     });
 
     it("should step over when paused", async () => {
-      const store = createStore(mockThreadFront);
+      const store = createStore(mockCommandClient);
       const { dispatch, getState } = store;
       const mockPauseInfo = createPauseInfo();
 
@@ -155,7 +155,7 @@ describe("pause", () => {
 
     it("should step over when paused before an await", async () => {
       features.asyncStepping = true;
-      const store = createStore(mockThreadFront);
+      const store = createStore(mockCommandClient);
       const { dispatch, getState } = store;
       const mockPauseInfo = createPauseInfo({
         sourceId: "await",
@@ -175,7 +175,7 @@ describe("pause", () => {
 
     it("should step over when paused after an await", async () => {
       const store = createStore({
-        ...mockThreadFront,
+        ...mockCommandClient,
         getBreakpointPositions: async () => ({ [2]: [1] }),
       });
       const { dispatch, getState } = store;
@@ -202,7 +202,7 @@ describe("pause", () => {
         column: 0,
       };
 
-      const store = createStore(mockThreadFront, {});
+      const store = createStore(mockCommandClient, {});
       const { dispatch, getState } = store;
       const mockPauseInfo = createPauseInfo(generatedLocation, {
         scope: {
@@ -279,7 +279,7 @@ describe("pause", () => {
         getGeneratedLocation: async location => location,
       };
 
-      const store = createStore(mockThreadFront, {}, sourceMapsMock);
+      const store = createStore(mockCommandClient, {}, sourceMapsMock);
       const { dispatch, getState } = store;
       const mockPauseInfo = createPauseInfo(generatedLocation);
 
@@ -340,7 +340,7 @@ describe("pause", () => {
         getGeneratedRangesForOriginal: async () => [],
       };
 
-      const store = createStore(mockThreadFront, {}, sourceMapsMock);
+      const store = createStore(mockCommandClient, {}, sourceMapsMock);
       const { dispatch, getState } = store;
       const mockPauseInfo = createPauseInfo(generatedLocation);
 
@@ -383,7 +383,7 @@ describe("pause", () => {
 
   describe("resumed", () => {
     it("should not evaluate expression while stepping", async () => {
-      const client = { ...mockThreadFront, evaluateExpressions: jest.fn() };
+      const client = { ...mockCommandClient, evaluateExpressions: jest.fn() };
       const { dispatch, getState } = createStore(client);
       const mockPauseInfo = createPauseInfo();
 
@@ -392,12 +392,12 @@ describe("pause", () => {
 
       const cx = selectors.getThreadContext(getState());
       dispatch(actions.stepIn(cx));
-      await dispatch(actions.resumed(mockThreadFront.actorID));
+      await dispatch(actions.resumed(mockCommandClient.actorID));
       expect(client.evaluateExpressions.mock.calls).toHaveLength(1);
     });
 
     it("resuming - will re-evaluate watch expressions", async () => {
-      const client = { ...mockThreadFront, evaluateExpressions: jest.fn() };
+      const client = { ...mockCommandClient, evaluateExpressions: jest.fn() };
       const store = createStore(client);
       const { dispatch, getState, cx } = store;
       const mockPauseInfo = createPauseInfo();
@@ -410,7 +410,7 @@ describe("pause", () => {
       client.evaluateExpressions.mockReturnValue(Promise.resolve(["YAY"]));
       await dispatch(actions.paused(mockPauseInfo));
 
-      await dispatch(actions.resumed(mockThreadFront.actorID));
+      await dispatch(actions.resumed(mockCommandClient.actorID));
       const expression = selectors.getExpression(getState(), "foo");
       expect(expression && expression.value).toEqual("YAY");
     });
diff --git a/devtools/client/debugger/src/actions/sources/tests/loadSource.spec.js b/devtools/client/debugger/src/actions/sources/tests/loadSource.spec.js
index 8f7e47391788..3fb7f4b5e6ed 100644
--- a/devtools/client/debugger/src/actions/sources/tests/loadSource.spec.js
+++ b/devtools/client/debugger/src/actions/sources/tests/loadSource.spec.js
@@ -14,14 +14,14 @@ import {
 } from "../../../utils/test-head";
 import {
   createSource,
-  sourceThreadFront,
-} from "../../tests/helpers/threadFront.js";
+  mockCommandClient,
+} from "../../tests/helpers/mockCommandClient";
 import { getBreakpointsList } from "../../../selectors";
 import { isFulfilled, isRejected } from "../../../utils/async-value";
 
 describe("loadSourceText", () => {
   it("should load source text", async () => {
-    const store = createStore(sourceThreadFront);
+    const store = createStore(mockCommandClient);
     const { dispatch, getState, cx } = store;
 
     const foo1Source = await dispatch(
@@ -59,7 +59,7 @@ describe("loadSourceText", () => {
 
     const store = createStore(
       {
-        ...sourceThreadFront,
+        ...mockCommandClient,
         sourceContents: async () => fooGenContent,
         getBreakpointPositions: async () => ({ "1": [0] }),
         getBreakableLines: async () => [],
@@ -223,7 +223,7 @@ describe("loadSourceText", () => {
   });
 
   it("should cache subsequent source text loads", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     const source = await dispatch(
       actions.newGeneratedSource(makeSource("foo1"))
@@ -238,7 +238,7 @@ describe("loadSourceText", () => {
   });
 
   it("should indicate a loading source", async () => {
-    const store = createStore(sourceThreadFront);
+    const store = createStore(mockCommandClient);
     const { dispatch, cx } = store;
 
     const source = await dispatch(
@@ -255,7 +255,7 @@ describe("loadSourceText", () => {
   });
 
   it("should indicate an errored source text", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     const source = await dispatch(
       actions.newGeneratedSource(makeSource("bad-id"))
diff --git a/devtools/client/debugger/src/actions/sources/tests/newSources.spec.js b/devtools/client/debugger/src/actions/sources/tests/newSources.spec.js
index 6982f42a3b71..1906e2ccaca3 100644
--- a/devtools/client/debugger/src/actions/sources/tests/newSources.spec.js
+++ b/devtools/client/debugger/src/actions/sources/tests/newSources.spec.js
@@ -20,12 +20,11 @@ const {
 } = selectors;
 import sourceQueue from "../../../utils/source-queue";
 
-// eslint-disable-next-line max-len
-import { sourceThreadFront as threadFront } from "../../tests/helpers/threadFront.js";
+import { mockCommandClient } from "../../tests/helpers/mockCommandClient";
 
 describe("sources - new sources", () => {
   it("should add sources to state", async () => {
-    const { dispatch, getState } = createStore(threadFront);
+    const { dispatch, getState } = createStore(mockCommandClient);
     await dispatch(actions.newGeneratedSource(makeSource("base.js")));
     await dispatch(actions.newGeneratedSource(makeSource("jquery.js")));
 
@@ -37,7 +36,7 @@ describe("sources - new sources", () => {
   });
 
   it("should not add multiple identical sources", async () => {
-    const { dispatch, getState } = createStore(threadFront);
+    const { dispatch, getState } = createStore(mockCommandClient);
 
     await dispatch(actions.newGeneratedSource(makeSource("base.js")));
     await dispatch(actions.newGeneratedSource(makeSource("base.js")));
@@ -46,7 +45,7 @@ describe("sources - new sources", () => {
   });
 
   it("should automatically select a pending source", async () => {
-    const { dispatch, getState, cx } = createStore(threadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
     const baseSourceURL = makeSourceURL("base.js");
     await dispatch(actions.selectSourceURL(cx, baseSourceURL));
 
@@ -61,7 +60,7 @@ describe("sources - new sources", () => {
 
   it("should add original sources", async () => {
     const { dispatch, getState } = createStore(
-      threadFront,
+      mockCommandClient,
       {},
       {
         getOriginalURLs: async () => ["magic.js"],
@@ -82,7 +81,7 @@ describe("sources - new sources", () => {
   it("should not attempt to fetch original sources if it's missing a source map url", async () => {
     const getOriginalURLs = jest.fn();
     const { dispatch } = createStore(
-      threadFront,
+      mockCommandClient,
       {},
       {
         getOriginalURLs,
@@ -97,7 +96,7 @@ describe("sources - new sources", () => {
   // eslint-disable-next-line
   it("should process new sources immediately, without waiting for source maps to be fetched first", async () => {
     const { dispatch, getState } = createStore(
-      threadFront,
+      mockCommandClient,
       {},
       {
         getOriginalURLs: async () => new Promise(_ => {}),
@@ -117,7 +116,7 @@ describe("sources - new sources", () => {
   // eslint-disable-next-line
   it("shouldn't let one slow loading source map delay all the other source maps", async () => {
     const dbg = createStore(
-      threadFront,
+      mockCommandClient,
       {},
       {
         getOriginalURLs: async source => {
@@ -153,7 +152,7 @@ describe("sources - new sources", () => {
     it(`should find two sources when same source with
       querystring`, async () => {
       const { getSourcesUrlsInSources } = selectors;
-      const { dispatch, getState } = createStore(threadFront);
+      const { dispatch, getState } = createStore(mockCommandClient);
       await dispatch(actions.newGeneratedSource(makeSource("base.js?v=1")));
       await dispatch(actions.newGeneratedSource(makeSource("base.js?v=2")));
       await dispatch(actions.newGeneratedSource(makeSource("diff.js?v=1")));
diff --git a/devtools/client/debugger/src/actions/sources/tests/prettyPrint.spec.js b/devtools/client/debugger/src/actions/sources/tests/prettyPrint.spec.js
index e84fd59f0ab6..a490949cb647 100644
--- a/devtools/client/debugger/src/actions/sources/tests/prettyPrint.spec.js
+++ b/devtools/client/debugger/src/actions/sources/tests/prettyPrint.spec.js
@@ -11,12 +11,12 @@ import {
   makeSource,
 } from "../../../utils/test-head";
 import { createPrettySource } from "../prettyPrint";
-import { sourceThreadFront } from "../../tests/helpers/threadFront.js";
+import { mockCommandClient } from "../../tests/helpers/mockCommandClient";
 import { isFulfilled } from "../../../utils/async-value";
 
 describe("sources - pretty print", () => {
   it("returns a pretty source for a minified file", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     const url = "base.js";
     const source = await dispatch(actions.newGeneratedSource(makeSource(url)));
@@ -42,7 +42,7 @@ describe("sources - pretty print", () => {
   });
 
   it("should create a source when first toggling pretty print", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     const source = await dispatch(
       actions.newGeneratedSource(makeSource("foobar.js"))
@@ -54,7 +54,7 @@ describe("sources - pretty print", () => {
   });
 
   it("should not make a second source when toggling pretty print", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     const source = await dispatch(
       actions.newGeneratedSource(makeSource("foobar.js"))
diff --git a/devtools/client/debugger/src/actions/sources/tests/querystrings.spec.js b/devtools/client/debugger/src/actions/sources/tests/querystrings.spec.js
index f1903edca6c1..a3d43c19c8db 100644
--- a/devtools/client/debugger/src/actions/sources/tests/querystrings.spec.js
+++ b/devtools/client/debugger/src/actions/sources/tests/querystrings.spec.js
@@ -13,11 +13,11 @@ import {
 const { getSourcesUrlsInSources } = selectors;
 
 // eslint-disable-next-line max-len
-import { sourceThreadFront as threadFront } from "../../tests/helpers/threadFront.js";
+import { mockCommandClient } from "../../tests/helpers/mockCommandClient";
 
 describe("sources - sources with querystrings", () => {
   it("should find two sources when same source with querystring", async () => {
-    const { dispatch, getState } = createStore(threadFront);
+    const { dispatch, getState } = createStore(mockCommandClient);
     await dispatch(actions.newGeneratedSource(makeSource("base.js?v=1")));
     await dispatch(actions.newGeneratedSource(makeSource("base.js?v=2")));
     await dispatch(actions.newGeneratedSource(makeSource("diff.js?v=1")));
diff --git a/devtools/client/debugger/src/actions/sources/tests/select.spec.js b/devtools/client/debugger/src/actions/sources/tests/select.spec.js
index fb52df7cf6f3..cda830bf52f1 100644
--- a/devtools/client/debugger/src/actions/sources/tests/select.spec.js
+++ b/devtools/client/debugger/src/actions/sources/tests/select.spec.js
@@ -23,7 +23,7 @@ const {
   getSelectedLocation,
 } = selectors;
 
-import { sourceThreadFront } from "../../tests/helpers/threadFront.js";
+import { mockCommandClient } from "../../tests/helpers/mockCommandClient";
 
 process.on("unhandledRejection", (reason, p) => {});
 
@@ -35,7 +35,7 @@ describe("sources", () => {
   it("should select a source", async () => {
     // Note that we pass an empty client in because the action checks
     // if it exists.
-    const store = createStore(sourceThreadFront);
+    const store = createStore(mockCommandClient);
     const { dispatch, getState } = store;
 
     const frame = makeFrame({ id: "1", sourceId: "foo1" });
@@ -69,7 +69,7 @@ describe("sources", () => {
   });
 
   it("should select next tab on tab closed if no previous tab", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     const fooSource = await dispatch(
       actions.newGeneratedSource(makeSource("foo.js"))
@@ -98,7 +98,7 @@ describe("sources", () => {
   });
 
   it("should open a tab for the source", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
     await dispatch(actions.newGeneratedSource(makeSource("foo.js")));
     dispatch(actions.selectLocation(cx, initialLocation("foo.js")));
 
@@ -108,7 +108,7 @@ describe("sources", () => {
   });
 
   it("should select previous tab on tab closed", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
     await dispatch(actions.newGeneratedSource(makeSource("foo.js")));
     await dispatch(actions.newGeneratedSource(makeSource("bar.js")));
 
@@ -127,7 +127,7 @@ describe("sources", () => {
   });
 
   it("should keep the selected source when other tab closed", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     await dispatch(actions.newGeneratedSource(makeSource("foo.js")));
     await dispatch(actions.newGeneratedSource(makeSource("bar.js")));
@@ -154,7 +154,7 @@ describe("sources", () => {
   });
 
   it("should not select new sources that lack a URL", async () => {
-    const { dispatch, getState } = createStore(sourceThreadFront);
+    const { dispatch, getState } = createStore(mockCommandClient);
 
     await dispatch(
       actions.newGeneratedSource({
@@ -169,7 +169,7 @@ describe("sources", () => {
   });
 
   it("sets and clears selected location correctly", async () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
     const source = await dispatch(
       actions.newGeneratedSource(makeSource("testSource"))
     );
@@ -188,7 +188,7 @@ describe("sources", () => {
   });
 
   it("sets and clears pending selected location correctly", () => {
-    const { dispatch, getState, cx } = createStore(sourceThreadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
     const url = "testURL";
     const options = { location: { line: "testLine" } };
 
@@ -207,7 +207,7 @@ describe("sources", () => {
   });
 
   it("should keep the generated the viewing context", async () => {
-    const store = createStore(sourceThreadFront);
+    const store = createStore(mockCommandClient);
     const { dispatch, getState, cx } = store;
     const baseSource = await dispatch(
       actions.newGeneratedSource(makeSource("base.js"))
@@ -224,7 +224,7 @@ describe("sources", () => {
 
   it("should keep the original the viewing context", async () => {
     const { dispatch, getState, cx } = createStore(
-      sourceThreadFront,
+      mockCommandClient,
       {},
       {
         getOriginalLocation: async location => ({ ...location, line: 12 }),
@@ -258,7 +258,7 @@ describe("sources", () => {
 
   it("should change the original the viewing context", async () => {
     const { dispatch, getState, cx } = createStore(
-      sourceThreadFront,
+      mockCommandClient,
       {},
       {
         getOriginalLocation: async location => ({ ...location, line: 12 }),
@@ -290,7 +290,7 @@ describe("sources", () => {
 
   describe("selectSourceURL", () => {
     it("should automatically select a pending source", async () => {
-      const { dispatch, getState, cx } = createStore(sourceThreadFront);
+      const { dispatch, getState, cx } = createStore(mockCommandClient);
       const baseSourceURL = makeSourceURL("base.js");
       await dispatch(actions.selectSourceURL(cx, baseSourceURL));
 
diff --git a/devtools/client/debugger/src/actions/tests/helpers/threadFront.js b/devtools/client/debugger/src/actions/tests/helpers/mockCommandClient.js
similarity index 58%
rename from devtools/client/debugger/src/actions/tests/helpers/threadFront.js
rename to devtools/client/debugger/src/actions/tests/helpers/mockCommandClient.js
index ae10a06afff3..90330ead963e 100644
--- a/devtools/client/debugger/src/actions/tests/helpers/threadFront.js
+++ b/devtools/client/debugger/src/actions/tests/helpers/mockCommandClient.js
@@ -4,11 +4,7 @@
 
 // @flow
 
-import type {
-  SourceActor,
-  SourceActorLocation,
-  BreakpointOptions,
-} from "../../../types";
+import type { SourceActor } from "../../../types";
 
 export function createSource(name: string, code?: string) {
   name = name.replace(/\..*$/, "");
@@ -36,33 +32,7 @@ const sources = [
   "jquery.js",
 ];
 
-export const simpleMockThreadFront = {
-  getBreakpointByLocation: (jest.fn(): any),
-  setBreakpoint: (location: SourceActorLocation, _condition: string) =>
-    Promise.resolve({ id: "hi", actualLocation: location }),
-
-  removeBreakpoint: (_id: string) => Promise.resolve(),
-
-  setBreakpointOptions: (
-    _id: string,
-    _location: SourceActorLocation,
-    _options: BreakpointOptions,
-    _noSliding: boolean
-  ) => Promise.resolve({ sourceId: "a", line: 5 }),
-  sourceContents: ({
-    source,
-  }: SourceActor): Promise<{| source: any, contentType: ?string |}> =>
-    new Promise((resolve, reject) => {
-      if (sources.includes(source)) {
-        resolve(createSource(source));
-      }
-
-      reject(`unknown source: ${source}`);
-    }),
-};
-
-// sources and tabs
-export const sourceThreadFront = {
+export const mockCommandClient = {
   sourceContents: function({
     source,
   }: SourceActor): Promise<{| source: any, contentType: ?string |}> {
@@ -75,6 +45,7 @@ export const sourceThreadFront = {
     });
   },
   setBreakpoint: async () => {},
+  removeBreakpoint: (_id: string) => Promise.resolve(),
   threadFront: async () => {},
   getFrameScopes: async () => {},
   evaluateExpressions: async () => {},
diff --git a/devtools/client/debugger/src/actions/tests/pending-breakpoints.spec.js b/devtools/client/debugger/src/actions/tests/pending-breakpoints.spec.js
index b35743524d6e..d928d6956548 100644
--- a/devtools/client/debugger/src/actions/tests/pending-breakpoints.spec.js
+++ b/devtools/client/debugger/src/actions/tests/pending-breakpoints.spec.js
@@ -10,7 +10,7 @@ import {
   mockPendingBreakpoint,
 } from "./helpers/breakpoints.js";
 
-import { simpleMockThreadFront } from "./helpers/threadFront.js";
+import { mockCommandClient } from "./helpers/mockCommandClient";
 
 import { asyncStore } from "../../utils/prefs";
 
@@ -47,7 +47,7 @@ import sourceMaps from "devtools-source-map";
 import { makePendingLocationId } from "../../utils/breakpoint";
 function mockClient(bpPos = {}) {
   return {
-    ...simpleMockThreadFront,
+    ...mockCommandClient,
 
     getBreakpointPositions: async () => bpPos,
     getBreakableLines: async () => [],
diff --git a/devtools/client/debugger/src/actions/tests/tabs.spec.js b/devtools/client/debugger/src/actions/tests/tabs.spec.js
index e0b371ca053a..210cc0373af7 100644
--- a/devtools/client/debugger/src/actions/tests/tabs.spec.js
+++ b/devtools/client/debugger/src/actions/tests/tabs.spec.js
@@ -12,11 +12,11 @@ import {
 } from "../../utils/test-head";
 const { getSelectedSource, getSourceTabs } = selectors;
 
-import { sourceThreadFront as threadFront } from "./helpers/threadFront.js";
+import { mockCommandClient } from "./helpers/mockCommandClient";
 
 describe("closing tabs", () => {
   it("closing a tab", async () => {
-    const { dispatch, getState, cx } = createStore(threadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     const fooSource = await dispatch(
       actions.newGeneratedSource(makeSource("foo.js"))
@@ -29,7 +29,7 @@ describe("closing tabs", () => {
   });
 
   it("closing the inactive tab", async () => {
-    const { dispatch, getState, cx } = createStore(threadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     const fooSource = await dispatch(
       actions.newGeneratedSource(makeSource("foo.js"))
@@ -45,7 +45,7 @@ describe("closing tabs", () => {
   });
 
   it("closing the only tab", async () => {
-    const { dispatch, getState, cx } = createStore(threadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     const fooSource = await dispatch(
       actions.newGeneratedSource(makeSource("foo.js"))
@@ -58,7 +58,7 @@ describe("closing tabs", () => {
   });
 
   it("closing the active tab", async () => {
-    const { dispatch, getState, cx } = createStore(threadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     await dispatch(actions.newGeneratedSource(makeSource("foo.js")));
     const barSource = await dispatch(
@@ -74,7 +74,7 @@ describe("closing tabs", () => {
   });
 
   it("closing many inactive tabs", async () => {
-    const { dispatch, getState, cx } = createStore(threadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     await dispatch(actions.newGeneratedSource(makeSource("foo.js")));
     await dispatch(actions.newGeneratedSource(makeSource("bar.js")));
@@ -97,7 +97,7 @@ describe("closing tabs", () => {
   });
 
   it("closing many tabs including the active tab", async () => {
-    const { dispatch, getState, cx } = createStore(threadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     await dispatch(actions.newGeneratedSource(makeSource("foo.js")));
     await dispatch(actions.newGeneratedSource(makeSource("bar.js")));
@@ -119,7 +119,7 @@ describe("closing tabs", () => {
   });
 
   it("closing all the tabs", async () => {
-    const { dispatch, getState, cx } = createStore(threadFront);
+    const { dispatch, getState, cx } = createStore(mockCommandClient);
 
     await dispatch(actions.newGeneratedSource(makeSource("foo.js")));
     await dispatch(actions.newGeneratedSource(makeSource("bar.js")));