--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_output_copy.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_output_copy.js
@@ -1,34 +1,32 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim: set ft=javascript ts=2 et sw=2 tw=80: */
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 
+/* import-globals-from head.js */
+
 "use strict";
 
 // Test copy to clipboard on the console output. See Bug 587617.
 const TEST_URI = "data:text/html,Test copy to clipboard on the console output";
 
 add_task(async function () {
   let hud = await openNewTabAndConsole(TEST_URI);
 
   const smokeMessage = "Hello world!";
   let onMessage = waitForMessage(hud, smokeMessage);
   ContentTask.spawn(gBrowser.selectedBrowser, smokeMessage, function (msg) {
     content.wrappedJSObject.console.log(msg);
   });
   const {node} = await onMessage;
   ok(true, "Message was logged");
 
-  const selection = node.ownerDocument.getSelection();
-  const range = document.createRange();
-  range.selectNodeContents(node);
-  selection.removeAllRanges();
-  selection.addRange(range);
+  let selection = selectNode(hud, node);
 
   const selectionString = selection.toString().trim();
   is(selectionString, smokeMessage, `selection has expected "${smokeMessage}" value`);
 
   await waitForClipboardPromise(
     () => {
       // The focus is on the JsTerm, so we need to blur it for the copy comand to work.
       node.ownerDocument.activeElement.blur();

--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_output_copy_newlines.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_output_copy_newlines.js
@@ -1,13 +1,15 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim: set ft=javascript ts=2 et sw=2 tw=80: */
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 
+/* import-globals-from head.js */
+
 "use strict";
 
 // Test that multiple messages are copied into the clipboard and that they are
 // separated by new lines. See bug 916997.
 const TEST_URI = "data:text/html,<meta charset=utf8>" +
   "Test copy multiple messages to clipboard";
 
 add_task(async function () {
@@ -19,21 +21,17 @@ add_task(async function () {
   ContentTask.spawn(gBrowser.selectedBrowser, messages, msgs => {
     msgs.forEach(msg => content.wrappedJSObject.console.log(msg));
   });
   const {node} = await onMessage;
   ok(node, "Messages were logged");
 
   // Select the whole output.
   const output = node.closest(".webconsole-output");
-  const selection = node.ownerDocument.getSelection();
-  const range = document.createRange();
-  range.selectNodeContents(output);
-  selection.removeAllRanges();
-  selection.addRange(range);
+  selectNode(hud, output);
 
   info("Wait for the clipboard to contain the text corresponding to all the messages");
   await waitForClipboardPromise(
     () => {
       // The focus is on the JsTerm, so we need to blur it for the copy comand to work.
       output.ownerDocument.activeElement.blur();
       goDoCommand("cmd_copy");
     },

--- a/devtools/client/webconsole/new-console-output/test/mochitest/head.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/head.js
@@ -545,8 +545,23 @@ async function openMessageInNetmonitor(t
 
   await waitUntil(() => {
     const selected = getSelectedRequest(store.getState());
     return selected && selected.url === url;
   });
 
   ok(true, "The attached url is correct.");
 }
+
+function selectNode(hud, node) {
+  let outputContainer = hud.ui.outputNode.querySelector(".webconsole-output");
+
+  // We must first blur the input or else we can't select anything.
+  outputContainer.ownerDocument.activeElement.blur();
+
+  let selection = outputContainer.ownerDocument.getSelection();
+  let range = document.createRange();
+  range.selectNodeContents(node);
+  selection.removeAllRanges();
+  selection.addRange(range);
+
+  return selection;
+}