Simplify Go Endpoints + Add Tests (#120)

This MR represents a major refactor of the Go codebase, as well as introducing tests for the handlers. The MR also introduces an endpoint to shutdown or restart the Go server, which may be useful for clients who want to refresh the state of the plugin after checking out branches. Finally, this MR adds a contributing document for users who want to make feature changes.

cmd/reviewer.go

@@ -22,13 +22,18 @@ type ReviewersRequestResponse struct {
 	Reviewers []int `json:"reviewers"`
 }
 
-func ReviewersHandler(w http.ResponseWriter, r *http.Request) {
-	c := r.Context().Value("client").(Client)
+/* reviewersHandler adds or removes reviewers from an MR */
+func (a *api) reviewersHandler(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
+	if r.Method != http.MethodPut {
+		w.Header().Set("Access-Control-Allow-Methods", http.MethodPut)
+		handleError(w, InvalidRequestError{}, "Expected PUT", http.StatusMethodNotAllowed)
+		return
+	}
 
 	body, err := io.ReadAll(r.Body)
 	if err != nil {
-		c.handleError(w, err, "Could not read request body", http.StatusBadRequest)
+		handleError(w, err, "Could not read request body", http.StatusBadRequest)
 		return
 	}
 
@@ -37,26 +42,25 @@ func ReviewersHandler(w http.ResponseWriter, r *http.Request) {
 	err = json.Unmarshal(body, &reviewerUpdateRequest)
 
 	if err != nil {
-		c.handleError(w, err, "Could not read JSON from request", http.StatusBadRequest)
+		handleError(w, err, "Could not read JSON from request", http.StatusBadRequest)
 		return
 	}
 
-	mr, res, err := c.git.MergeRequests.UpdateMergeRequest(c.projectId, c.mergeId, &gitlab.UpdateMergeRequestOptions{
+	mr, res, err := a.client.UpdateMergeRequest(a.projectInfo.ProjectId, a.projectInfo.MergeId, &gitlab.UpdateMergeRequestOptions{
 		ReviewerIDs: &reviewerUpdateRequest.Ids,
 	})
 
 	if err != nil {
-		c.handleError(w, err, "Could not modify merge request reviewers", http.StatusBadRequest)
+		handleError(w, err, "Could not modify merge request reviewers", http.StatusInternalServerError)
 		return
 	}
 
-	if res.StatusCode != http.StatusOK {
-		c.handleError(w, err, "Could not modify merge request reviewers", http.StatusBadRequest)
+	if res.StatusCode >= 300 {
+		handleError(w, GenericError{endpoint: "/mr/reviewer"}, "Could not modify merge request reviewers", res.StatusCode)
 		return
 	}
 
 	w.WriteHeader(http.StatusOK)
-
 	response := ReviewerUpdateResponse{
 		SuccessResponse: SuccessResponse{
 			Message: "Reviewers updated",
@@ -67,6 +71,6 @@ func ReviewersHandler(w http.ResponseWriter, r *http.Request) {
 
 	err = json.NewEncoder(w).Encode(response)
 	if err != nil {
-		c.handleError(w, err, "Could not encode response", http.StatusInternalServerError)
+		handleError(w, err, "Could not encode response", http.StatusInternalServerError)
 	}
 }