Fix #22: Improve alerting provider tests by mocking HTTP client

test/mock.go

@@ -0,0 +1,9 @@
+package test
+
+import "net/http"
+
+type MockRoundTripper func(r *http.Request) *http.Response
+
+func (f MockRoundTripper) RoundTrip(r *http.Request) (*http.Response, error) {
+	return f(r), nil
+}