1 files changed, 143 insertions, 0 deletions
diff --git a/devtools/client/webconsole/test/browser/browser_jsterm_helpers_no_override.js b/devtools/client/webconsole/test/browser/browser_jsterm_helpers_no_override.js
new file mode 100644
index 0000000000..674e92c038
--- /dev/null
+++ b/devtools/client/webconsole/test/browser/browser_jsterm_helpers_no_override.js
@@ -0,0 +1,143 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Check that console helpers are not set when existing variables with similar names
+// exists in the page.
+
+const TEST_URI = `data:text/html,<!DOCTYPE html><script>
+    var $ = "var_$";
+    const $$ = "const_$$";
+    let help = "let_help";
+    globalThis.values = "globalThis_values";
+    function keys() {
+      return "function_keys";
+    }
+
+    function pauseInDebugger() {
+      let $x = "let_$x";
+      debugger;
+    }
+  </script>`;
+
+add_task(async function () {
+  const hud = await openNewTabAndConsole(TEST_URI);
+
+  let message = await executeAndWaitForResultMessage(hud, "$", "var_$");
+  ok(message, "$ was not overridden");
+
+  message = await executeAndWaitForResultMessage(hud, "$$", "const_$$");
+  ok(message, "$$ was not overridden");
+
+  message = await executeAndWaitForResultMessage(hud, "help", "let_help");
+  ok(message, "help was not overridden");
+
+  message = await executeAndWaitForResultMessage(
+    hud,
+    "values",
+    "globalThis_values"
+  );
+  ok(message, "values was not overridden");
+
+  message = await executeAndWaitForResultMessage(
+    hud,
+    "keys()",
+    "function_keys"
+  );
+  ok(message, "keys was not overridden");
+
+  info("Pause in Debugger");
+  await openDebugger();
+  const toolbox = gDevTools.getToolboxForTab(gBrowser.selectedTab);
+  const dbg = createDebuggerContext(toolbox);
+  SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+    content.wrappedJSObject.pauseInDebugger();
+  });
+  await pauseDebugger(dbg);
+
+  info("Go back to Console");
+  await toolbox.selectTool("webconsole");
+  message = await executeAndWaitForResultMessage(hud, "$x", "let_$x");
+  ok(
+    message,
+    `frame variable "$x" was not overridden while paused in the debugger`
+  );
+
+  await resume(dbg);
+});
+
+add_task(async function () {
+  // Test the behavior when the variables are declared in the script.
+
+  const hud = await openNewTabAndConsole("data:text/html,Nothing");
+
+  let message = await executeAndWaitForResultMessage(
+    hud,
+    "var $ = 'var_$'; $",
+    "var_$"
+  );
+  ok(message, "$ was not overridden");
+
+  message = await executeAndWaitForResultMessage(
+    hud,
+    "const $$ = 'const_$$'; $$",
+    "const_$$"
+  );
+  ok(message, "$$ was not overridden");
+
+  message = await executeAndWaitForResultMessage(
+    hud,
+    "function keys() { return 'function_keys';  } keys()",
+    "function_keys"
+  );
+  ok(message, "keys was not overridden");
+
+  // Hoisted variable.
+  message = await executeAndWaitForResultMessage(
+    hud,
+    "{ var clear = 'var_clear';  } clear",
+    "var_clear"
+  );
+  ok(message, "clear was not overridden");
+
+  // Hoisted function.
+  message = await executeAndWaitForResultMessage(
+    hud,
+    "{ function help() { return 'function_help';  } } help()",
+    "function_help"
+  );
+  ok(message, "help was not overridden");
+
+  // Lexical variables are not hoisted.
+  message = await executeAndWaitForResultMessage(
+    hud,
+    "{ let values = 'let_values';  } typeof values",
+    "function"
+  );
+  ok(message, "values was not overridden because it's not global");
+});
+
+add_task(async function () {
+  // NOTE: Open a new page to use the same binding name again.
+
+  const hud = await openNewTabAndConsole("data:text/html,Nothing");
+
+  // An assignment on `globalThis` property inside the script doesn't shadow
+  // the helper binding.
+  let message = await executeAndWaitForResultMessage(
+    hud,
+    "globalThis.values = 'globalThis_values'; typeof values",
+    "function"
+  );
+  ok(message, "values was overridden because it's not declaration");
+
+  // Executing `values` again shadows the helper binding, given it exists
+  // before the execution.
+  message = await executeAndWaitForResultMessage(
+    hud,
+    "values",
+    "globalThis_values"
+  );
+  ok(message, "values was not overridden if it exists before the execution");
+});