diff --git a/remote/test/browser/browser_page_javascriptDialog_alert.js b/remote/test/browser/browser_page_javascriptDialog_alert.js
index a6d5ff1f89c3..2bcab178b617 100644
--- a/remote/test/browser/browser_page_javascriptDialog_alert.js
+++ b/remote/test/browser/browser_page_javascriptDialog_alert.js
@@ -3,12 +3,10 @@
 
 "use strict";
 
-const TEST_URI = "data:text/html;charset=utf-8,default-test-page";
-
 // Test a browser alert is detected via Page.javascriptDialogOpening and can be
 // closed with Page.handleJavaScriptDialog
 add_task(async function() {
-  const { client, tab } = await setupTestForUri(TEST_URI);
+  const { client, tab } = await setup();
 
   const { Page } = client;
 
diff --git a/remote/test/browser/browser_page_javascriptDialog_beforeunload.js b/remote/test/browser/browser_page_javascriptDialog_beforeunload.js
index ce752d5c59f2..500ed6a1ac22 100644
--- a/remote/test/browser/browser_page_javascriptDialog_beforeunload.js
+++ b/remote/test/browser/browser_page_javascriptDialog_beforeunload.js
@@ -3,8 +3,6 @@
 
 "use strict";
 
-const TEST_URI = "data:text/html;charset=utf-8,default-test-page";
-
 // Test beforeunload dialog events.
 add_task(async function() {
   info("Allow to trigger onbeforeunload without user interaction");
@@ -15,7 +13,7 @@ add_task(async function() {
     SpecialPowers.pushPrefEnv(options, resolve);
   });
 
-  const { client, tab } = await setupTestForUri(TEST_URI);
+  const { client, tab } = await setup();
 
   const { Page } = client;
 
diff --git a/remote/test/browser/browser_page_javascriptDialog_confirm.js b/remote/test/browser/browser_page_javascriptDialog_confirm.js
index 015742156c64..dfea7958c9e7 100644
--- a/remote/test/browser/browser_page_javascriptDialog_confirm.js
+++ b/remote/test/browser/browser_page_javascriptDialog_confirm.js
@@ -3,12 +3,10 @@
 
 "use strict";
 
-const TEST_URI = "data:text/html;charset=utf-8,default-test-page";
-
 // Test for window.confirm(). Check that the dialog is correctly detected and that it can
 // be rejected or accepted.
 add_task(async function() {
-  const { client, tab } = await setupTestForUri(TEST_URI);
+  const { client, tab } = await setup();
 
   const { Page } = client;
 
diff --git a/remote/test/browser/browser_page_javascriptDialog_otherTarget.js b/remote/test/browser/browser_page_javascriptDialog_otherTarget.js
index 40746eb140f2..73cff3b019fe 100644
--- a/remote/test/browser/browser_page_javascriptDialog_otherTarget.js
+++ b/remote/test/browser/browser_page_javascriptDialog_otherTarget.js
@@ -3,13 +3,13 @@
 
 "use strict";
 
-const TEST_URI = "data:text/html;charset=utf-8,default-test-page";
-const OTHER_URI = "data:text/html;charset=utf-8,other-test-page";
+const FIRST_DOC = toDataURL("default-test-page");
+const SECOND_DOC = toDataURL("other-test-page");
 
 // Test that javascript dialog events are emitted by the page domain only if
 // the dialog is created for the window of the target.
 add_task(async function() {
-  const { client, tab } = await setupTestForUri(TEST_URI);
+  const { client, tab } = await setupForURL(FIRST_DOC);
 
   const { Page } = client;
 
@@ -24,7 +24,7 @@ add_task(async function() {
   info("Open another tab");
   const otherTab = await BrowserTestUtils.openNewForegroundTab(
     gBrowser,
-    OTHER_URI
+    SECOND_DOC
   );
   is(gBrowser.selectedTab, otherTab, "Selected tab is now the new tab");
 
diff --git a/remote/test/browser/browser_page_javascriptDialog_prompt.js b/remote/test/browser/browser_page_javascriptDialog_prompt.js
index dc3efaebb83d..c3e30be11815 100644
--- a/remote/test/browser/browser_page_javascriptDialog_prompt.js
+++ b/remote/test/browser/browser_page_javascriptDialog_prompt.js
@@ -3,12 +3,10 @@
 
 "use strict";
 
-const TEST_URI = "data:text/html;charset=utf-8,default-test-page";
-
 // Test for window.prompt(). Check that the dialog is correctly detected and that it can
 // be rejected or accepted, with a custom prompt text.
 add_task(async function() {
-  const { client, tab } = await setupTestForUri(TEST_URI);
+  const { client, tab } = await setup();
 
   const { Page } = client;
 
diff --git a/remote/test/browser/browser_runtime_callFunctionOn.js b/remote/test/browser/browser_runtime_callFunctionOn.js
index 5e491943a3fe..4b6bba4364fb 100644
--- a/remote/test/browser/browser_runtime_callFunctionOn.js
+++ b/remote/test/browser/browser_runtime_callFunctionOn.js
@@ -7,7 +7,7 @@
 // See also browser_runtime_evaluate, which covers basic usages of this method.
 
 add_task(async function() {
-  const { client } = await setupForURL(toDataURL(""));
+  const { client } = await setup();
 
   const firstContext = await testRuntimeEnable(client);
   const contextId = firstContext.id;
diff --git a/remote/test/browser/browser_runtime_get_properties.js b/remote/test/browser/browser_runtime_get_properties.js
index 42700a146cfd..7fc121b09ce8 100644
--- a/remote/test/browser/browser_runtime_get_properties.js
+++ b/remote/test/browser/browser_runtime_get_properties.js
@@ -6,7 +6,7 @@
 // Test the Runtime remote object
 
 add_task(async function() {
-  const { client } = await setupForURL(toDataURL(""));
+  const { client } = await setup();
 
   const firstContext = await testRuntimeEnable(client);
   const contextId = firstContext.id;
diff --git a/remote/test/browser/browser_runtime_remote_objects.js b/remote/test/browser/browser_runtime_remote_objects.js
index 7cb45ae3c9e8..c23b334a1460 100644
--- a/remote/test/browser/browser_runtime_remote_objects.js
+++ b/remote/test/browser/browser_runtime_remote_objects.js
@@ -6,7 +6,7 @@
 // Test the Runtime remote object
 
 add_task(async function() {
-  const { client } = await setupForURL(toDataURL(""));
+  const { client } = await setup();
 
   const firstContext = await testRuntimeEnable(client);
   const contextId = firstContext.id;
diff --git a/remote/test/browser/head.js b/remote/test/browser/head.js
index a9606c90228b..183d9822018f 100644
--- a/remote/test/browser/head.js
+++ b/remote/test/browser/head.js
@@ -101,6 +101,14 @@ function getTargets(CDP) {
   });
 }
 
+/**
+ * Set up test environment in same fashion as setupForURL(),
+ * except using an empty document.
+ */
+async function setup() {
+  return setupForURL(toDataURL(""));
+}
+
 /**
  * Set up test environment by starting the remote agent, connecting
  * the CDP client over loopback, and creating a fresh tab to avoid