[Fix] preserve stack traces for returned Promises (async/await)

lib/test.js

@@ -16,6 +16,7 @@ var isEnumerable = bind.call(Function.call, Object.prototype.propertyIsEnumerabl
 var toLowerCase = bind.call(Function.call, String.prototype.toLowerCase);
 var isProto = bind.call(Function.call, Object.prototype.isPrototypeOf);
 var $test = bind.call(Function.call, RegExp.prototype.test);
+var objectToString = bind.call(Function.call, Object.prototype.toString);
 
 module.exports = Test;
 
@@ -111,7 +112,11 @@ Test.prototype.run = function () {
                 self.end();
             }
         })['catch'](function onError(err) {
-            self.fail(err);
+            if (err instanceof Error || objectToString(err) === '[object Error]') {
+                self.ifError(err);
+            } else {
+                self.fail(err);
+            }
             self.end();
         });
         return;

test/async-await.js

@@ -217,9 +217,10 @@ tap.test('async-error', function (t) {
             'ok 1 before throw',
             'not ok 2 Error: oopsie',
             '  ---',
-            '    operator: fail',
+            '    operator: error',
             '    stack: |-',
-            '      Error: Error: oopsie',
+            '      Error: oopsie',
+            '          at Test.myTest ($TEST/async-await/async-error.js:$LINE:$COL)',
             '          [... stack stripped ...]',
             '  ...',
             '',
@@ -245,3 +246,42 @@ tap.test('async-error', function (t) {
         t.end();
     });
 });
+
+tap.test('async-bug', function (t) {
+    runProgram('async-await', 'async-bug.js', function (r) {
+        var stdout = r.stdout.toString('utf8');
+        var lines = stdout.split('\n');
+        lines = lines.filter(function (line) {
+            return !/^(\s+)at(\s+)<anonymous>$/.test(line);
+        });
+        stdout = lines.join('\n');
+
+        t.same(stripFullStack(stdout), [
+            'TAP version 13',
+            '# async-error',
+            'ok 1 before throw',
+            'ok 2 should be strictly equal',
+            'not ok 3 TypeError: Cannot read property \'length\' of null',
+            '  ---',
+            '    operator: error',
+            '    stack: |-',
+            '      TypeError: Cannot read property \'length\' of null',
+            '          at myCode ($TEST/async-await/async-bug.js:$LINE:$COL)',
+            '          at Test.myTest ($TEST/async-await/async-bug.js:$LINE:$COL)',
+            '  ...',
+            '',
+            '1..3',
+            '# tests 3',
+            '# pass  2',
+            '# fail  1',
+            '',
+            '',
+        ].join('\n'));
+        t.same(r.exitCode, 1);
+
+        var stderr = r.stderr.toString('utf8');
+
+        t.same(stderr, '');
+        t.end();
+    });
+});

test/async-await/async-bug.js

@@ -0,0 +1,32 @@
+'use strict';
+
+var test = require('../../');
+
+function myCode(arr) {
+    let sum = 0;
+    // oops forgot to handle null
+    for (let i = 0; i < arr.length; i++) {
+        sum += arr[i];
+    }
+    return sum;
+}
+
+test('async-error', async function myTest(t) {
+    await sleep(100);
+    t.ok(true, 'before throw');
+
+    const sum = myCode([1, 2, 3]);
+    t.equal(sum, 6);
+
+    const sum2 = myCode(null);
+    t.equal(sum2, 0);
+
+    t.end();
+});
+
+
+function sleep(ms) {
+    return new Promise((resolve) => {
+        setTimeout(resolve, ms);
+    });
+}

test/promise_fail.js

@@ -20,21 +20,29 @@ tap.test('callback returning rejected promise should cause that test (and only t
         }
 
         var strippedString = stripFullStack(rowsString);
+        var lines = strippedString.split('\n');
+        lines = lines.filter(function (line) {
+            return !/^(\s+)at(\s+)(?:Test\.)?<anonymous>(?:$|\s)/.test(line);
+        });
+        strippedString = lines.join('\n');
 
         // hack for consistency across all versions of node
         // some versions produce a longer stack trace for some reason
         // since this doesn't affect the validity of the test, the extra line is removed if present
         // the regex just removes the lines "at <anonymous>" and "[... stack stripped ...]" if they occur together
-        strippedString = strippedString.replace(/.+at <anonymous>\n.+\[\.\.\. stack stripped \.\.\.\]\n/, '');
+        strippedString = strippedString
+            .replace(/.+at (?:Test\.)?<anonymous>\n.+\[\.\.\. stack stripped \.\.\.\]\n/g, '')
+            .replace(/(?:(.+)\[\.\.\. stack stripped \.\.\.\]\n)+/g, '$1[... stack stripped ...]\n');
 
         tt.same(strippedString, [
             'TAP version 13',
             '# promise',
             'not ok 1 Error: rejection message',
             '  ---',
-            '    operator: fail',
+            '    operator: error',
             '    stack: |-',
-            '      Error: Error: rejection message',
+            '      Error: rejection message',
+            '          at $TEST/promises/fail.js:$LINE:$COL',
             '          [... stack stripped ...]',
             '  ...',
             '# after',
@@ -63,22 +71,30 @@ tap.test('subtest callback returning rejected promise should cause that subtest
         }
 
         var strippedString = stripFullStack(rowsString);
+        var lines = strippedString.split('\n');
+        lines = lines.filter(function (line) {
+            return !/^(\s+)at(\s+)(?:Test\.)?<anonymous>(?:$|\s)/.test(line);
+        });
+        strippedString = lines.join('\n');
 
         // hack for consistency across all versions of node
         // some versions produce a longer stack trace for some reason
         // since this doesn't affect the validity of the test, the extra line is removed if present
         // the regex just removes the lines "at <anonymous>" and "[... stack stripped ...]" if they occur together
-        strippedString = strippedString.replace(/.+at <anonymous>\n.+\[\.\.\. stack stripped \.\.\.\]\n/, '');
+        strippedString = strippedString
+            .replace(/.+at (?:Test\.)?<anonymous>\n.+\[\.\.\. stack stripped \.\.\.\]\n/, '')
+            .replace(/(?:(.+)\[\.\.\. stack stripped \.\.\.\]\n)+/g, '$1[... stack stripped ...]\n');
 
         tt.same(strippedString, [
             'TAP version 13',
             '# promise',
             '# sub test that should fail',
             'not ok 1 Error: rejection message',
             '  ---',
-            '    operator: fail',
+            '    operator: error',
             '    stack: |-',
-            '      Error: Error: rejection message',
+            '      Error: rejection message',
+            '          at $TEST/promises/subTests.js:$LINE:$COL',
             '          [... stack stripped ...]',
             '  ...',
             '# sub test that should pass',