test, integration: Add cluster primitives to integration framework

This further extends the integration framework to add some simple
primitives for building clusters. More complex primitives and patterns
can be added in the future, but this should serve the general cases.

integration/util_test.go

@@ -63,3 +63,21 @@ file "${root}/mgmt-hello-world" {
 		t.Errorf("code samples differ")
 	}
 }
+
+func TestParsePort(t *testing.T) {
+	if port, err := ParsePort("http://127.0.0.1:2379"); err != nil {
+		t.Errorf("could not determine port: %+v", err)
+	} else if port != 2379 {
+		t.Errorf("unexpected port: %d", port)
+	}
+
+	if port, err := ParsePort("http://127.0.0.1:2381"); err != nil {
+		t.Errorf("could not determine port: %+v", err)
+	} else if port != 2381 {
+		t.Errorf("unexpected port: %d", port)
+	}
+
+	if port, err := ParsePort("http://127.0.0.1"); err == nil {
+		t.Errorf("expected error, got: %d", port)
+	}
+}