assert: show thrown message in doesNotThrow()

assert.doesNotThrow() should show actual error message instead of "Got unwanted exception" which is not really helpful.
nodejs · krydos · Apr 2, 2017 · Jul 15, 2017 · d023feb7c1b50578446de84e5fe2abe57428e6f0
commit d023feb7c1b50578446de84e5fe2abe57428e6f0
diff --git a/lib/assert.js b/lib/assert.js
@@ -546,7 +546,10 @@ function innerThrows(shouldThrow, block, expected, message) {
   } else if (actual !== undefined) {
     if (!expected || expectedException(actual, expected)) {
       details = message ? `: ${message}` : '.';
-      fail(actual, expected, `Got unwanted exception${details}`, fail);
+      fail(actual,
+           expected,
+           `Got unwanted exception${details}\n${actual.message}`,
+           fail);
     }
     throw actual;
   }

diff --git a/test/parallel/test-assert.js b/test/parallel/test-assert.js
@@ -468,6 +468,34 @@ assert.throws(() => {
 }, /Got unwanted exception: user message/,
               'a.doesNotThrow ignores user message');
 
+{
+  let threw = false;
+  try {
+    assert.doesNotThrow(makeBlock(thrower, Error), 'user message');
+  } catch (e) {
+    threw = true;
+    common.expectsError({
+      code: 'ERR_ASSERTION',
+      message: /Got unwanted exception: user message\n\[object Object\]/
+    })(e);
+  }
+  assert.ok(threw);
+}
+
+{
+  let threw = false;
+  try {
+    assert.doesNotThrow(makeBlock(thrower, Error));
+  } catch (e) {
+    threw = true;
+    common.expectsError({
+      code: 'ERR_ASSERTION',
+      message: /Got unwanted exception\.\n\[object Object\]/
+    })(e);
+  }
+  assert.ok(threw);
+}
+
 // make sure that validating using constructor really works
 {
   let threw = false;