#1: Add case when Mojang's API returns empty response

api/mojang/mojang.go

@@ -28,6 +28,8 @@ type ProfileInfo struct {
 	IsDemo   bool   `json:"demo,omitempty"`
 }
 
+// Exchanges usernames array to array of uuids
+// See https://wiki.vg/Mojang_API#Playernames_-.3E_UUIDs
 func UsernamesToUuids(usernames []string) ([]*ProfileInfo, error) {
 	requestBody, _ := json.Marshal(usernames)
 	request, err := http.NewRequest("POST", "https://api.mojang.com/profiles/minecraft", bytes.NewBuffer(requestBody))
@@ -43,8 +45,8 @@ func UsernamesToUuids(usernames []string) ([]*ProfileInfo, error) {
 	}
 	defer response.Body.Close()
 
-	if response.StatusCode == 429 {
-		return nil, &TooManyRequestsError{}
+	if responseErr := validateResponse(response); responseErr != nil {
+		return nil, responseErr
 	}
 
 	var result []*ProfileInfo
@@ -55,6 +57,8 @@ func UsernamesToUuids(usernames []string) ([]*ProfileInfo, error) {
 	return result, nil
 }
 
+// Obtains textures information for provided uuid
+// See https://wiki.vg/Mojang_API#UUID_-.3E_Profile_.2B_Skin.2FCape
 func UuidToTextures(uuid string, signed bool) (*SignedTexturesResponse, error) {
 	url := "https://sessionserver.mojang.com/session/minecraft/profile/" + uuid
 	if signed {
@@ -72,8 +76,8 @@ func UuidToTextures(uuid string, signed bool) (*SignedTexturesResponse, error) {
 	}
 	defer response.Body.Close()
 
-	if response.StatusCode == 429 {
-		return nil, &TooManyRequestsError{}
+	if responseErr := validateResponse(response); responseErr != nil {
+		return nil, responseErr
 	}
 
 	var result *SignedTexturesResponse
@@ -84,9 +88,30 @@ func UuidToTextures(uuid string, signed bool) (*SignedTexturesResponse, error) {
 	return result, nil
 }
 
+func validateResponse(response *http.Response) error {
+	switch response.StatusCode {
+	case 204:
+		return &EmptyResponse{}
+	case 429:
+		return &TooManyRequestsError{}
+	}
+
+	return nil
+}
+
+// Mojang API doesn't return a 404 Not Found error for non-existent data identifiers
+// Instead, they return 204 with an empty body
+type EmptyResponse struct {
+}
+
+func (*EmptyResponse) Error() string {
+	return "Empty Response"
+}
+
+// When you exceed the set limit of requests, this error will be returned
 type TooManyRequestsError struct {
 }
 
-func (e *TooManyRequestsError) Error() string {
+func (*TooManyRequestsError) Error() string {
 	return "Too Many Requests"
 }

api/mojang/mojang_test.go

@@ -146,7 +146,27 @@ func TestUuidToTextures(t *testing.T) {
 		}
 	})
 
-	t.Run("handle too many requests error", func(t *testing.T) {
+	t.Run("handle empty response", func(t *testing.T) {
+		assert := testify.New(t)
+
+		defer gock.Off()
+		gock.New("https://sessionserver.mojang.com").
+			Get("/session/minecraft/profile/4566e69fc90748ee8d71d7ba5aa00d20").
+			Reply(204).
+			BodyString("")
+
+		client := &http.Client{}
+		gock.InterceptClient(client)
+
+		HttpClient = client
+
+		result, err := UuidToTextures("4566e69fc90748ee8d71d7ba5aa00d20", false)
+		assert.Nil(result)
+		assert.IsType(&EmptyResponse{}, err)
+		assert.EqualError(err, "Empty Response")
+	})
+
+	t.Run("handle too many requests response", func(t *testing.T) {
 		assert := testify.New(t)
 
 		defer gock.Off()

api/mojang/queue/queue.go

@@ -146,12 +146,12 @@ func (ctx *JobsQueue) getTextures(uuid string) *mojang.SignedTexturesResponse {
 
 	shouldCache := true
 	result, err := uuidToTextures(uuid, true)
-	if err != nil {
-		if _, ok := err.(*mojang.TooManyRequestsError); !ok {
-			panic(err)
-		}
-
+	switch err.(type) {
+	case *mojang.EmptyResponse:
+	case *mojang.TooManyRequestsError:
 		shouldCache = false
+	case error:
+		panic(err)
 	}
 
 	if shouldCache && result != nil {

api/mojang/queue/queue_test.go

@@ -293,7 +293,7 @@ func (suite *QueueTestSuite) TestDoNothingWhenNoTasks() {
 	suite.Iterate()
 }
 
-func (suite *QueueTestSuite) TestHandle429ResponseWhenExchangingUsernamesToUuids() {
+func (suite *QueueTestSuite) TestHandleTooManyRequestsResponseWhenExchangingUsernamesToUuids() {
 	suite.Storage.On("GetUuid", "maksimkurb").Once().Return("", &ValueNotFound{})
 	// Storage.StoreUuid, Storage.GetTextures and Storage.StoreTextures shouldn't be called
 	suite.MojangApi.On("UsernameToUuids", []string{"maksimkurb"}).Once().Return(nil, &mojang.TooManyRequestsError{})
@@ -305,7 +305,27 @@ func (suite *QueueTestSuite) TestHandle429ResponseWhenExchangingUsernamesToUuids
 	suite.Assert().Nil(<-resultChan)
 }
 
-func (suite *QueueTestSuite) TestHandle429ResponseWhenRequestingUsersTextures() {
+func (suite *QueueTestSuite) TestHandleEmptyResponseWhenRequestingUsersTextures() {
+	suite.Storage.On("GetUuid", "maksimkurb").Once().Return("", &ValueNotFound{})
+	suite.Storage.On("StoreUuid", "maksimkurb", "0d252b7218b648bfb86c2ae476954d32").Once()
+	suite.Storage.On("GetTextures", "0d252b7218b648bfb86c2ae476954d32").Once().Return(nil, &ValueNotFound{})
+	// Storage.StoreTextures shouldn't be called
+	suite.MojangApi.On("UsernameToUuids", []string{"maksimkurb"}).Once().Return([]*mojang.ProfileInfo{
+		{Id: "0d252b7218b648bfb86c2ae476954d32", Name: "maksimkurb"},
+	}, nil)
+	suite.MojangApi.On("UuidToTextures", "0d252b7218b648bfb86c2ae476954d32", true).Once().Return(
+		nil,
+		&mojang.EmptyResponse{},
+	)
+
+	resultChan := suite.Queue.GetTexturesForUsername("maksimkurb")
+
+	suite.Iterate()
+
+	suite.Assert().Nil(<-resultChan)
+}
+
+func (suite *QueueTestSuite) TestHandleTooManyRequestsResponseWhenRequestingUsersTextures() {
 	suite.Storage.On("GetUuid", "maksimkurb").Once().Return("", &ValueNotFound{})
 	suite.Storage.On("StoreUuid", "maksimkurb", "0d252b7218b648bfb86c2ae476954d32").Once()
 	suite.Storage.On("GetTextures", "0d252b7218b648bfb86c2ae476954d32").Once().Return(nil, &ValueNotFound{})