Added Diagnostic and Diagnosticf.

These produce diagnostic output, as defined by the TAP spec.

Author: tesujimath

util/tap/tap.go

@@ -111,3 +111,13 @@ func (t *T) Count() int {
 func (t *T) AutoPlan() {
 	t.printf("1..%d\n", t.Count())
 }
+
+// Diagnostic generates a diagnostic from the message.
+func (t *T) Diagnostic(message string) {
+	t.printf("# %s\n", message)
+}
+
+// Diagnosticf generates a diagnostic from the format string and arguments.
+func (t *T) Diagnosticf(format string, a ...interface{}) {
+	t.printf("# "+format+"\n", a...)
+}

util/tap/test/diagnostic/main.go

@@ -0,0 +1,11 @@
+package main
+
+import "github.com/mndrix/tap-go"
+
+func main() {
+	t := tap.New()
+	t.Header(1)
+	t.Diagnostic("expecting all to be well")
+	t.Diagnosticf("here's some perfectly magical output: %d %s 0x%X.", 6, "abracadabra", 28)
+	t.Pass("all good")
+}