Update test to be Abs and include function name in error output

Author: leighmcculloch

src/testing/testing.go

@@ -18,11 +18,11 @@
 // For more detail, run ``go help test'' and ``go help testflag''.
 //
 // A simple test function looks like this:
-//     func TestHello(t *testing.T) {
-//         got := fmt.Sprintf("hello %s", "world")
-//         want := "hello world"
+//     func TestAbs(t *testing.T) {
+//         got := Abs(-1)
+//         want := 1
 //         if got != want {
-//             t.Errorf("got %q, want %q", got, want)
+//             t.Errorf("Abs(-1) returns %d, want %d", got, want)
 //         }
 //     }
 //