assert: add partial support for evaluated code in simple assert

This makes sure using `assert.ok()` in `new Function()` statements
visualizes the actual call site in the error message.

PR-URL: https://github.com/nodejs/node/pull/27781
Reviewed-By: Rich Trott <rtrott@gmail.com>

lib/assert.js

@@ -269,42 +269,55 @@ function getErrMessage(message, fn) {
   Error.prepareStackTrace = tmpPrepare;
 
   const filename = call.getFileName();
-
-  if (!filename) {
-    return message;
-  }
-
   const line = call.getLineNumber() - 1;
   let column = call.getColumnNumber() - 1;
+  let identifier;
+  let code;
 
-  const identifier = `${filename}${line}${column}`;
+  if (filename) {
+    identifier = `${filename}${line}${column}`;
+
+    // Skip Node.js modules!
+    if (filename.endsWith('.js') &&
+        NativeModule.exists(filename.slice(0, -3))) {
+      errorCache.set(identifier, undefined);
+      return;
+    }
+  } else {
+    const fn = call.getFunction();
+    if (!fn) {
+      return message;
+    }
+    code = String(fn);
+    identifier = `${code}${line}${column}`;
+  }
 
   if (errorCache.has(identifier)) {
     return errorCache.get(identifier);
   }
 
-  // Skip Node.js modules!
-  if (filename.endsWith('.js') && NativeModule.exists(filename.slice(0, -3))) {
-    errorCache.set(identifier, undefined);
-    return;
-  }
-
   let fd;
   try {
     // Set the stack trace limit to zero. This makes sure unexpected token
     // errors are handled faster.
     Error.stackTraceLimit = 0;
 
-    if (decoder === undefined) {
-      const { StringDecoder } = require('string_decoder');
-      decoder = new StringDecoder('utf8');
+    if (filename) {
+      if (decoder === undefined) {
+        const { StringDecoder } = require('string_decoder');
+        decoder = new StringDecoder('utf8');
+      }
+      fd = openSync(filename, 'r', 0o666);
+      // Reset column and message.
+      [column, message] = getCode(fd, line, column);
+      // Flush unfinished multi byte characters.
+      decoder.end();
+    } else {
+      for (let i = 0; i < line; i++) {
+        code = code.slice(code.indexOf('\n') + 1);
+      }
+      [column, message] = parseCode(code, column);
     }
-
-    fd = openSync(filename, 'r', 0o666);
-    // Reset column and message.
-    [column, message] = getCode(fd, line, column);
-    // Flush unfinished multi byte characters.
-    decoder.end();
     // Always normalize indentation, otherwise the message could look weird.
     if (message.includes('\n')) {
       if (EOL === '\r\n') {

test/parallel/test-assert.js

@@ -859,6 +859,13 @@ common.expectsError(
   {
     code: 'ERR_ASSERTION',
     type: assert.AssertionError,
+    message: 'The expression evaluated to a falsy value:\n\n  assert(1 === 2)\n'
+  }
+);
+assert.throws(
+  () => eval('console.log("FOO");\nassert.ok(1 === 2);'),
+  {
+    code: 'ERR_ASSERTION',
     message: 'false == true'
   }
 );