add tests to ensure module id returns correctly

internal/module/test/http-client_test.go

@@ -14,6 +14,7 @@ func TestHTTPClientFromRegistry(t *testing.T) {
 	}
 
 	moduleInstance, err := registration.New(config.ModuleConfig{
+		Id:   "test",
 		Type: "http.client",
 	})
 
@@ -21,6 +22,10 @@ func TestHTTPClientFromRegistry(t *testing.T) {
 		t.Fatalf("failed to create http.client module: %s", err)
 	}
 
+	if moduleInstance.Id() != "test" {
+		t.Fatalf("http.client module has wrong id: %s", moduleInstance.Id())
+	}
+
 	if moduleInstance.Type() != "http.client" {
 		t.Fatalf("http.client module has wrong type: %s", moduleInstance.Type())
 	}