Ensure 'this' in test implementations is null

We shouldn't expose the test instance through 'this'.

Author: novemberborn

lib/test.js

@@ -312,7 +312,7 @@ class Test {
 		try {
 			return {
 				ok: true,
-				retval: this.fn(this.createExecutionContext())
+				retval: this.fn.call(null, this.createExecutionContext())
 			};
 		} catch (err) {
 			return {

test/reporters/mini.regular.log

@@ -225,7 +225,7 @@ stderr
     https://github.com/avajs/ava#throwsfunctionpromise-error-message
 
   fn (test.js:35:9)
-  Test.t [as fn] (test.js:37:11)
+  t (test.js:37:11)
 
 
 
@@ -254,7 +254,7 @@ stderr
     https://github.com/avajs/ava#throwsfunctionpromise-error-message
 
   fn (test.js:42:9)
-  Test.t [as fn] (test.js:44:14)
+  t (test.js:44:14)
 
 
 
@@ -275,7 +275,7 @@ stderr
 
   Unhandled rejection in test/fixture/report/regular/unhandled-rejection.js
   Error: Can't catch me
-  Test.t [as fn] (unhandled-rejection.js:4:17)
+  t (unhandled-rejection.js:4:17)
 
   Unhandled rejection in test/fixture/report/regular/unhandled-rejection.js
   Threw non-error: {"message":"null"}

test/reporters/tap.failfast.log

@@ -6,7 +6,7 @@ not ok 1 - a › fails
     name: AssertionError
     message: Test failed via `t.fail()`
     assertion: fail
-    at: 'Test.t [as fn] (a.js:3:22)'
+    at: 't (a.js:3:22)'
   ...
 ---tty-stream-chunk-separator
 

test/reporters/tap.failfast2.log

@@ -6,7 +6,7 @@ not ok 1 - a › fails
     name: AssertionError
     message: Test failed via `t.fail()`
     assertion: fail
-    at: 'Test.t [as fn] (a.js:3:22)'
+    at: 't (a.js:3:22)'
   ...
 ---tty-stream-chunk-separator
 

test/reporters/tap.regular.log

@@ -20,7 +20,7 @@ ok 4 - unhandled-rejection › unhandled non-error rejection
 not ok 5 - Can't catch me
   ---
     name: Error
-    at: 'Test.t [as fn] (unhandled-rejection.js:4:17)'
+    at: 't (unhandled-rejection.js:4:17)'
   ...
 ---tty-stream-chunk-separator
 # null
@@ -58,7 +58,7 @@ not ok 12 - test › fails
     name: AssertionError
     message: Test failed via `t.fail()`
     assertion: fail
-    at: 'Test.t [as fn] (test.js:12:22)'
+    at: 't (test.js:12:22)'
   ...
 ---tty-stream-chunk-separator
 # test › known failure
@@ -81,7 +81,7 @@ not ok 15 - test › logs
     name: AssertionError
     message: Test failed via `t.fail()`
     assertion: fail
-    at: 'Test.t [as fn] (test.js:21:4)'
+    at: 't (test.js:21:4)'
   ...
 ---tty-stream-chunk-separator
 # test › formatted
@@ -93,7 +93,7 @@ not ok 16 - test › formatted
       'Difference:': |-
         - 'foo'
         + 'bar'
-    at: 'Test.t [as fn] (test.js:25:4)'
+    at: 't (test.js:25:4)'
   ...
 ---tty-stream-chunk-separator
 # test › power-assert
@@ -104,7 +104,7 @@ not ok 17 - test › power-assert
     operator: '!'
     values:
       'Value is not falsy:': '''bar'''
-    at: 'Test.t [as fn] (test.js:30:4)'
+    at: 't (test.js:30:4)'
   ...
 ---tty-stream-chunk-separator
 # test › bad throws

test/reporters/verbose.regular.log

@@ -15,7 +15,7 @@
 ---tty-stream-chunk-separator
   Unhandled rejection in test/fixture/report/regular/unhandled-rejection.js
   Error: Can't catch me
-  Test.t [as fn] (unhandled-rejection.js:4:17)
+  t (unhandled-rejection.js:4:17)
 
 
 
@@ -167,7 +167,7 @@ stderr
     https://github.com/avajs/ava#throwsfunctionpromise-error-message
 
   fn (test.js:35:9)
-  Test.t [as fn] (test.js:37:11)
+  t (test.js:37:11)
 
 
 
@@ -196,7 +196,7 @@ stderr
     https://github.com/avajs/ava#throwsfunctionpromise-error-message
 
   fn (test.js:42:9)
-  Test.t [as fn] (test.js:44:14)
+  t (test.js:44:14)
 
 
 

test/test.js

@@ -758,3 +758,10 @@ test('snapshot assertion cannot be skipped when updating snapshots', t => {
 		t.is(result.error.message, 'Snapshot assertions cannot be skipped when updating snapshots');
 	});
 });
+
+test('implementation runs with null scope', t => {
+	return ava(function (a) {
+		a.pass();
+		t.is(this, null);
+	}).run();
+});