assert: improve error messages

From now on all error messages produced by `assert` in strict mode
will produce a error diff.

PR-URL: https://github.com/nodejs/node/pull/17615
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/lib/assert.js b/lib/assert.js
index db8ae35e07..9931ce9c22 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -48,6 +48,10 @@ const meta = [
 
 const escapeFn = (str) => meta[str.charCodeAt(0)];
 
+const ERR_DIFF_DEACTIVATED = 0;
+const ERR_DIFF_NOT_EQUAL = 1;
+const ERR_DIFF_EQUAL = 2;
+
 // The assert module provides functions that throw
 // AssertionError's when particular conditions are not met. The
 // assert module must conform to the following interface.
@@ -283,7 +287,8 @@ assert.deepStrictEqual = function deepStrictEqual(actual, expected, message) {
       expected,
       message,
       operator: 'deepStrictEqual',
-      stackStartFn: deepStrictEqual
+      stackStartFn: deepStrictEqual,
+      errorDiff: this === strict ? ERR_DIFF_EQUAL : ERR_DIFF_DEACTIVATED
     });
   }
 };
@@ -296,7 +301,8 @@ function notDeepStrictEqual(actual, expected, message) {
       expected,
       message,
       operator: 'notDeepStrictEqual',
-      stackStartFn: notDeepStrictEqual
+      stackStartFn: notDeepStrictEqual,
+      errorDiff: this === strict ? ERR_DIFF_NOT_EQUAL : ERR_DIFF_DEACTIVATED
     });
   }
 }
@@ -308,7 +314,8 @@ assert.strictEqual = function strictEqual(actual, expected, message) {
       expected,
       message,
       operator: 'strictEqual',
-      stackStartFn: strictEqual
+      stackStartFn: strictEqual,
+      errorDiff: this === strict ? ERR_DIFF_EQUAL : ERR_DIFF_DEACTIVATED
     });
   }
 };
@@ -320,7 +327,8 @@ assert.notStrictEqual = function notStrictEqual(actual, expected, message) {
       expected,
       message,
       operator: 'notStrictEqual',
-      stackStartFn: notStrictEqual
+      stackStartFn: notStrictEqual,
+      errorDiff: this === strict ? ERR_DIFF_NOT_EQUAL : ERR_DIFF_DEACTIVATED
     });
   }
 };