Moved unit test files inside same directory as test target

The unit tests were inside the `gateway/tests` directory which had no
effect to the coverage for `go test`. Therefore, moved the tests inside
the same directory as the test target.

Signed-off-by: Ken Fukuyama <kenfdev@gmail.com>

gateway/metrics/add_metrics_test.go

@@ -0,0 +1,103 @@
+package metrics
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/openfaas/faas/gateway/requests"
+)
+
+type FakePrometheusQueryFetcher struct {
+}
+
+func (q FakePrometheusQueryFetcher) Fetch(query string) (*VectorQueryResponse, error) {
+	val := []byte(`{"status":"success","data":{"resultType":"vector","result":[{"metric":{"code":"200","function_name":"func_echoit"},"value":[1509267827.752,"1"]}]}}`)
+	queryRes := VectorQueryResponse{}
+	err := json.Unmarshal(val, &queryRes)
+	return &queryRes, err
+}
+
+func makeFakePrometheusQueryFetcher() FakePrometheusQueryFetcher {
+	return FakePrometheusQueryFetcher{}
+}
+
+func Test_PrometheusMetrics_MixedInto_Services(t *testing.T) {
+	functionsHandler := makeFunctionsHandler()
+	fakeQuery := makeFakePrometheusQueryFetcher()
+
+	handler := AddMetricsHandler(functionsHandler, fakeQuery)
+
+	rr := httptest.NewRecorder()
+	request, _ := http.NewRequest(http.MethodGet, "/system/functions", nil)
+	handler.ServeHTTP(rr, request)
+
+	if status := rr.Code; status != http.StatusOK {
+		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusOK)
+	}
+
+	if rr.Header().Get("Content-Type") != "application/json" {
+		t.Errorf("Want application/json content-type, got: %s", rr.Header().Get("Content-Type"))
+	}
+	body := rr.Body.String()
+	if len(body) == 0 {
+		t.Errorf("Want content-length > 0, got: %d", len(rr.Body.String()))
+	}
+	results := []requests.Function{}
+	json.Unmarshal([]byte(rr.Body.String()), &results)
+	if len(results) == 0 {
+		t.Errorf("Want %d function, got: %d", 1, len(results))
+	}
+	if results[0].InvocationCount != 1 {
+		t.Errorf("InvocationCount want: %d , got: %f", 1, results[0].InvocationCount)
+	}
+}
+
+func Test_FunctionsHandler_ReturnsJSONAndOneFunction(t *testing.T) {
+	functionsHandler := makeFunctionsHandler()
+
+	rr := httptest.NewRecorder()
+	request, err := http.NewRequest(http.MethodGet, "/system/functions", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	functionsHandler.ServeHTTP(rr, request)
+
+	if status := rr.Code; status != http.StatusOK {
+		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusOK)
+	}
+
+	if rr.Header().Get("Content-Type") != "application/json" {
+		t.Errorf("Want application/json content-type, got: %s", rr.Header().Get("Content-Type"))
+	}
+
+	if len(rr.Body.String()) == 0 {
+		t.Errorf("Want content-length > 0, got: %d", len(rr.Body.String()))
+	}
+
+}
+
+func makeFunctionsHandler() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		functions := []requests.Function{
+			requests.Function{
+				Name:     "func_echoit",
+				Replicas: 0,
+			},
+		}
+		bytesOut, marshalErr := json.Marshal(&functions)
+		if marshalErr != nil {
+			log.Fatal(marshalErr.Error())
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+		_, err := w.Write(bytesOut)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+}