test: make common.mustNotCall show file:linenumber

When a test fails via `common.mustNotCall` it is sometimes hard to
determine exactly what was called. This modification stores the
caller's file and line number by using the V8 Error API to capture
a stack at the time `common.mustNotCall()` is called. In the event
of failure, this information is printed.

This change also exposes a new function in test/common, `getCallSite()`
which accepts a `function` and returns a `String` with the file name and
line number for the function.

PR-URL: https://github.com/nodejs/node/pull/17257
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Khaidi Chu <i@2333.moe>

2 files changed, 21 insertions, 1 deletions

diff --git a/test/common/README.md b/test/common/README.md
index 7fa47677ca..f48215836e 100644
--- a/test/common/README.md
+++ b/test/common/README.md
@@ -133,6 +133,12 @@ a reason otherwise.
 
 Returns an instance of all possible `ArrayBufferView`s of the provided Buffer.
 
+### getCallSite(func)
+* `func` [<Function>]
+* return [<String>]
+
+Returns the file name and line number for the provided Function.
+
 ### globalCheck
 * [<Boolean>]
 
diff --git a/test/common/index.js b/test/common/index.js
index a78f900877..2cf188abe5 100644
--- a/test/common/index.js
+++ b/test/common/index.js
@@ -566,9 +566,23 @@ exports.canCreateSymLink = function() {
   return true;
 };
 
+exports.getCallSite = function getCallSite(top) {
+  const originalStackFormatter = Error.prepareStackTrace;
+  Error.prepareStackTrace = (err, stack) =>
+    `${stack[0].getFileName()}:${stack[0].getLineNumber()}`;
+  const err = new Error();
+  Error.captureStackTrace(err, top);
+  // with the V8 Error API, the stack is not formatted until it is accessed
+  err.stack;
+  Error.prepareStackTrace = originalStackFormatter;
+  return err.stack;
+};
+
 exports.mustNotCall = function(msg) {
+  const callSite = exports.getCallSite(exports.mustNotCall);
   return function mustNotCall() {
-    assert.fail(msg || 'function should not have been called');
+    assert.fail(
+      `${msg || 'function should not have been called'} at ${callSite}`);
   };
 };