test: fill gaps in library root

notify_test.go

@@ -1,6 +1,7 @@
 package notify
 
 import (
+	"context"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
@@ -97,3 +98,21 @@ func TestNewWithServices(t *testing.T) {
 		}
 	}
 }
+
+func TestGlobal(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	if err := Send(ctx, "subject", "message"); err != nil {
+		t.Errorf("Send() with no receivers returned error: %v", err)
+	}
+
+	UseServices(mail.New("", ""), nil)
+	if len(std.notifiers) != 1 {
+		t.Errorf("UseServices(mail.New()) was expected to have 1 notifier but had %d", len(std.notifiers))
+	}
+
+	if err := Send(ctx, "subject", "message"); err == nil {
+		t.Error("Send() with invalid mail returned no error")
+	}
+}

send_test.go

@@ -38,4 +38,25 @@ func TestNotifySend(t *testing.T) {
 	if err := n.Send(ctx, "subject", "message"); err == nil {
 		t.Errorf("Send() invalid mail returned no error: %v", err)
 	}
+
+	// After disabling the Notifier, Send() should return silently.
+	n.WithOptions(Disable)
+
+	if err := n.Send(ctx, "subject", "message"); err != nil {
+		t.Errorf("Send() of disabled Notifier returned error: %v", err)
+	}
+
+	n.WithOptions(Enable)
+
+	// Smuggle in a nil service. This usually never happens, since UseServices filters out nil services. But, it's good
+	// to test anyway.
+	n.notifiers = make([]Notifier, 0)
+	n.notifiers = append(n.notifiers, nil)
+
+	if err := n.Send(ctx, "subject", "message"); err != nil {
+		t.Errorf("Send() of disabled Notifier returned no error: %v", err)
+	}
+	if r := recover(); r != nil {
+		t.Errorf("Send() with nil service panicked: %v", r)
+	}
 }