fix: set default transport when caller provides uninitialized one

kong/client_test.go

@@ -3,6 +3,7 @@ package kong
 import (
 	"context"
 	"io/ioutil"
+	"net/http"
 	"os"
 	"testing"
 
@@ -57,31 +58,55 @@ func TestRootJSON(T *testing.T) {
 }
 
 func TestDo(T *testing.T) {
-	assert := assert.New(T)
-	require := require.New(T)
-
-	client, err := NewTestClient(nil, nil)
-	assert.NoError(err)
-	assert.NotNil(client)
-
-	req, err := client.NewRequest("GET", "/does-not-exist", nil, nil)
-	assert.NoError(err)
-	require.NotNil(req)
-	resp, err := client.Do(context.Background(), req, nil)
-	assert.True(IsNotFoundErr(err))
-	require.NotNil(resp)
-	assert.Equal(404, resp.StatusCode)
+	testcases := []struct {
+		name           string
+		httpClientFunc func() *http.Client
+	}{
+		{
+			name:           "nil http.Client",
+			httpClientFunc: func() *http.Client { return nil },
+		},
+		{
+			name:           "default/uninitialized http.Client",
+			httpClientFunc: func() *http.Client { return &http.Client{} },
+		},
+		{
+			name:           "default/uninitialized http.Client with HTTPClientWithHeaders",
+			httpClientFunc: func() *http.Client { return HTTPClientWithHeaders(&http.Client{}, nil) },
+		},
+	}
 
-	req, err = client.NewRequest("POST", "/", nil, nil)
-	assert.NoError(err)
-	require.NotNil(req)
-	resp, err = client.Do(context.Background(), req, nil)
-	require.NotNil(err)
-	require.NotNil(resp)
-	body, err := ioutil.ReadAll(resp.Body)
-	assert.NoError(err)
-	assert.Empty(body)
-	assert.Equal(405, resp.StatusCode)
+	for _, tc := range testcases {
+		tc := tc
+
+		T.Run(tc.name, func(T *testing.T) {
+			assert := assert.New(T)
+			require := require.New(T)
+
+			client, err := NewTestClient(nil, tc.httpClientFunc())
+			require.NoError(err)
+			require.NotNil(client)
+
+			req, err := client.NewRequest("GET", "/does-not-exist", nil, nil)
+			assert.NoError(err)
+			require.NotNil(req)
+			resp, err := client.Do(context.Background(), req, nil)
+			assert.True(IsNotFoundErr(err), "got %v", err)
+			require.NotNil(resp)
+			assert.Equal(404, resp.StatusCode)
+
+			req, err = client.NewRequest("POST", "/", nil, nil)
+			assert.NoError(err)
+			require.NotNil(req)
+			resp, err = client.Do(context.Background(), req, nil)
+			require.NotNil(err)
+			require.NotNil(resp)
+			body, err := ioutil.ReadAll(resp.Body)
+			assert.NoError(err)
+			assert.Empty(body)
+			assert.Equal(405, resp.StatusCode)
+		})
+	}
 }
 
 func TestMain(m *testing.M) {

kong/custom_entity_service.go

@@ -88,7 +88,7 @@ func (s *CustomEntityService) Create(ctx context.Context,
 	o := entity.Object()
 	// Necessary to Marshal an empty map
 	// as {} and not null
-	if o == nil || len(o) == 0 {
+	if len(o) == 0 {
 		o = make(map[string]interface{})
 	}
 	req, err := s.client.NewRequest(method, queryPath, nil, o)
@@ -123,7 +123,7 @@ func (s *CustomEntityService) Update(ctx context.Context,
 	o := entity.Object()
 	// Necessary to Marshal an empty map
 	// as {} and not null
-	if o == nil || len(o) == 0 {
+	if len(o) == 0 {
 		o = make(map[string]interface{})
 	}
 	req, err := s.client.NewRequest("PATCH", queryPath, nil, o)

kong/utils.go

@@ -115,6 +115,11 @@ func HTTPClientWithHeaders(client *http.Client,
 		res.Transport = defaultTransport
 	} else {
 		res = client
+		// If a client with nil transport has been provided then set it to http's
+		// default transport so that the caller is still able to use it.
+		if res.Transport == nil {
+			res.Transport = http.DefaultTransport.(*http.Transport)
+		}
 	}
 	res.Transport = headerRoundTripper{
 		headers: headers,

kong/utils_test.go

@@ -2,6 +2,7 @@ package kong
 
 import (
 	"net/http"
+	"net/http/httptest"
 	"reflect"
 	"testing"
 
@@ -524,3 +525,26 @@ func TestFillUpstreamsDefaults(T *testing.T) {
 		})
 	}
 }
+
+func TestHTTPClientWithHeaders(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	assert.NotPanics(t,
+		func() {
+			client := HTTPClientWithHeaders(&http.Client{}, nil)
+			assert.NotNil(t, client)
+		},
+		"creating Kong's HTTP client using default/uninitialized http.Client shouldn't panic",
+	)
+
+	assert.NotPanics(t,
+		func() {
+			client := HTTPClientWithHeaders(nil, nil)
+			assert.NotNil(t, client)
+		},
+		"creating Kong's HTTP client using nil http.Client shouldn't panic",
+	)
+}