AfterFunc underlying function is executed in its own goroutine

[smirnov-vs]

Original AfterFunc executes function in its own goroutine
Mock should do it in the same way, otherwise tests doesn't cover races with this kind of timer

[vincentbernat]

This introduces race conditions in the tests. To fix them:

diff --git a/clock_test.go b/clock_test.go
index 73813fb679c5..053ca6ece4d3 100644
--- a/clock_test.go
+++ b/clock_test.go
@@ -604,24 +604,25 @@ func ExampleMock_After() {
 func ExampleMock_AfterFunc() {
        // Create a new mock clock.
        clock := NewMock()
-       count := 0
+       var count counter
+       count.incr()

        // Execute a function after 10 mock seconds.
        clock.AfterFunc(10*time.Second, func() {
-               count = 100
+               count.incr()
        })
        gosched()

        // Print the starting value.
-       fmt.Printf("%s: %d\n", clock.Now().UTC(), count)
+       fmt.Printf("%s: %d\n", clock.Now().UTC(), count.get())

        // Move the clock forward 10 seconds and print the new value.
        clock.Add(10 * time.Second)
-       fmt.Printf("%s: %d\n", clock.Now().UTC(), count)
+       fmt.Printf("%s: %d\n", clock.Now().UTC(), count.get())

        // Output:
-       // 1970-01-01 00:00:00 +0000 UTC: 0
-       // 1970-01-01 00:00:10 +0000 UTC: 100
+       // 1970-01-01 00:00:00 +0000 UTC: 1
+       // 1970-01-01 00:00:10 +0000 UTC: 2
 }

 func ExampleMock_Sleep() {
@@ -728,9 +729,9 @@ func TestMock_AddAfterFuncRace(t *testing.T) {

        mockedClock := NewMock()

-       called := false
+       var called counter
        defer func() {
-               if !called {
+               if called.get() == 0 {
                        t.Errorf("AfterFunc did not call the function")
                }
        }()
@@ -741,7 +742,7 @@ func TestMock_AddAfterFuncRace(t *testing.T) {
                <-start

                mockedClock.AfterFunc(time.Millisecond, func() {
-                       called = true
+                       called.incr()
                })
        }()

(this patch also includes code for #42)

[djmitche]

(The second commit is from @vincentbernat's comment)

[djmitche]

Done, and released as 1.3.3