Add draft for mock http client for unittesting

mock/client.go

@@ -0,0 +1,146 @@
+package mock
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"regexp"
+)
+
+type EndpointPattern = *regexp.Regexp
+
+// Users
+var UsersGetEndpoint EndpointPattern = regexp.MustCompile(`^\/users\/[a-zA-Z]+`)
+
+// Orgs
+var OrgsListEndpoint = regexp.MustCompile(`^\/users\/([a-z]+\/orgs|orgs)$`)
+var OrgsGetEndpoint = regexp.MustCompile(`^\/orgs\/[a-z]+`)
+
+type RequestMatch struct {
+	EndpointPattern EndpointPattern
+	Method          string // GET or POST
+}
+
+func (rm *RequestMatch) Match(r *http.Request) bool {
+	if (r.Method == rm.Method) &&
+		r.URL.Path == rm.EndpointPattern.FindString(r.URL.Path) {
+		return true
+	}
+
+	return false
+}
+
+var RequestMatchUsersGet = RequestMatch{
+	EndpointPattern: UsersGetEndpoint,
+	Method:          http.MethodGet,
+}
+
+var RequestMatchOrganizationsList = RequestMatch{
+	EndpointPattern: OrgsListEndpoint,
+	Method:          http.MethodGet,
+}
+
+type MockRoundTripper struct {
+	RequestMocks map[RequestMatch][][]byte
+}
+
+// RoundTrip implements http.RoundTripper interface
+func (mrt *MockRoundTripper) RoundTrip(r *http.Request) (*http.Response, error) {
+	for requestMatch, respBodies := range mrt.RequestMocks {
+		if requestMatch.Match(r) {
+			if len(respBodies) == 0 {
+				fmt.Printf(
+					"no more available mocked responses for endpoit %s\n",
+					r.URL.Path,
+				)
+
+				fmt.Println("please add the required RequestMatch to the MockHttpClient. Eg.")
+				fmt.Println(`
+				mockedHttpClient := NewMockHttpClient(
+					WithRequestMatch(
+						RequestMatchUsersGet,
+						MustMarshall(github.User{
+							Name: github.String("foobar"),
+						}),
+					),
+					WithRequestMatch(
+						RequestMatchOrganizationsList,
+						MustMarshall([]github.Organization{
+							{
+								Name: github.String("foobar123"),
+							},
+						}),
+					),
+				)
+				`)
+
+				panic(nil)
+			}
+
+			resp := respBodies[0]
+
+			defer func(mrt *MockRoundTripper, rm RequestMatch) {
+				mrt.RequestMocks[rm] = mrt.RequestMocks[rm][1:]
+			}(mrt, requestMatch)
+
+			re := bytes.NewReader(resp)
+
+			return &http.Response{
+				StatusCode: http.StatusOK,
+				Body:       ioutil.NopCloser(re),
+			}, nil
+		}
+	}
+
+	return nil, fmt.Errorf(
+		"couldn find a mock request that matches the request sent to: %s",
+		r.URL.Path,
+	)
+
+}
+
+var _ http.RoundTripper = &MockRoundTripper{}
+
+type MockHttpClientOption func(*MockRoundTripper)
+
+func WithRequestMatch(
+	rm RequestMatch,
+	marshalled []byte,
+) MockHttpClientOption {
+	return func(mrt *MockRoundTripper) {
+		if _, found := mrt.RequestMocks[rm]; !found {
+			mrt.RequestMocks[rm] = make([][]byte, 0)
+		}
+
+		mrt.RequestMocks[rm] = append(
+			mrt.RequestMocks[rm],
+			marshalled,
+		)
+	}
+}
+
+func NewMockHttpClient(options ...MockHttpClientOption) *http.Client {
+	rt := &MockRoundTripper{
+		RequestMocks: make(map[RequestMatch][][]byte),
+	}
+
+	for _, o := range options {
+		o(rt)
+	}
+
+	return &http.Client{
+		Transport: rt,
+	}
+}
+
+func MustMarshal(v interface{}) []byte {
+	b, err := json.Marshal(v)
+
+	if err == nil {
+		return b
+	}
+
+	panic(err)
+}

mock/client_test.go

@@ -0,0 +1,59 @@
+package mock
+
+import (
+	"context"
+	"testing"
+
+	"github.com/google/go-github/v37/github"
+)
+
+func TestMockClient(t *testing.T) {
+	ctx := context.Background()
+
+	mockedHttpClient := NewMockHttpClient(
+		WithRequestMatch(
+			RequestMatchUsersGet,
+			MustMarshal(github.User{
+				Name: github.String("foobar"),
+			}),
+		),
+		WithRequestMatch(
+			RequestMatchOrganizationsList,
+			MustMarshal([]github.Organization{
+				{
+					Name: github.String("foobar123thisorgwasmocked"),
+				},
+			}),
+		),
+	)
+
+	c := github.NewClient(mockedHttpClient)
+
+	user, _, userErr := c.Users.Get(ctx, "someUser")
+
+	if user == nil || user.Name == nil || *user.Name != "foobar" {
+		t.Fatalf("User name is %s, want foobar", user)
+	}
+
+	if userErr != nil {
+		t.Errorf("User err is %s, want nil", userErr.Error())
+	}
+
+	orgs, _, err := c.Organizations.List(
+		ctx,
+		*(user.Name),
+		nil,
+	)
+
+	if len(orgs) != 1 {
+		t.Errorf("Orgs len is %d want 1", len(orgs))
+	}
+
+	if err != nil {
+		t.Errorf("Err is %s, want nil", err.Error())
+	}
+
+	if *(orgs[0].Name) != "foobar123thisorgwasmocked" {
+		t.Errorf("orgs[0].Name is %s, want %s", *orgs[0].Name, "foobar123thisorgdoesnotexist")
+	}
+}