Fix MR Selection, Go Code Refactor (#358)

refactor: Refactors the Go codebase into a more modular and idiomatic approach
fix: require selection of specific MR when there are multiple targets for a given source branch
feat: Allows for the passing of Gitlab's filter options when choosing an MR, improves MR selection
feat: API to choose an MR from a list based on the provided username's involvement as an assignee/reviewer/author

This is a #MINOR release

cmd/app/test_helpers.go

@@ -0,0 +1,149 @@
+package app
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/harrisoncramer/gitlab.nvim/cmd/app/git"
+	"github.com/xanzy/go-gitlab"
+)
+
+var errorFromGitlab = errors.New("Some error from Gitlab")
+
+/* The assert function is a helper function used to check two comparables */
+func assert[T comparable](t *testing.T, got T, want T) {
+	t.Helper()
+	if got != want {
+		t.Errorf("Got '%v' but wanted '%v'", got, want)
+	}
+}
+
+/* Will create a new request with the given method, endpoint and body */
+func makeRequest(t *testing.T, method string, endpoint string, body any) *http.Request {
+	t.Helper()
+
+	var reader io.Reader
+	if body != nil {
+		j, err := json.Marshal(body)
+		if err != nil {
+			t.Fatal(err)
+		}
+		reader = bytes.NewReader(j)
+	}
+
+	request, err := http.NewRequest(method, endpoint, reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return request
+}
+
+/* Make response makes a simple response value with the right status code */
+func makeResponse(status int) *gitlab.Response {
+	return &gitlab.Response{
+		Response: &http.Response{
+			StatusCode: status,
+			Body:       http.NoBody,
+		},
+	}
+}
+
+var testProjectData = data{
+	projectInfo: &ProjectInfo{},
+	gitInfo: &git.GitData{
+		BranchName: "some-branch",
+	},
+}
+
+func getSuccessData(t *testing.T, svc ServiceWithHandler, request *http.Request) SuccessResponse {
+	res := httptest.NewRecorder()
+	svc.handler(res, request)
+
+	var data SuccessResponse
+	err := json.Unmarshal(res.Body.Bytes(), &data)
+	if err != nil {
+		t.Error(err)
+	}
+	return data
+}
+
+func getFailData(t *testing.T, svc ServiceWithHandler, request *http.Request) ErrorResponse {
+	res := httptest.NewRecorder()
+	svc.handler(res, request)
+
+	var data ErrorResponse
+	err := json.Unmarshal(res.Body.Bytes(), &data)
+	if err != nil {
+		t.Error(err)
+	}
+	return data
+}
+
+type testBase struct {
+	errFromGitlab bool
+	status        int
+}
+
+// Helper for easily mocking bad responses or errors from Gitlab
+func (f *testBase) handleGitlabError() (*gitlab.Response, error) {
+	if f.errFromGitlab {
+		return nil, errorFromGitlab
+	}
+	if f.status == 0 {
+		f.status = 200
+	}
+	return makeResponse(f.status), nil
+}
+
+func checkErrorFromGitlab(t *testing.T, data ErrorResponse, msg string) {
+	t.Helper()
+	assert(t, data.Status, http.StatusInternalServerError)
+	assert(t, data.Message, msg)
+	assert(t, data.Details, errorFromGitlab.Error())
+}
+
+func checkBadMethod(t *testing.T, data ErrorResponse, methods ...string) {
+	t.Helper()
+	assert(t, data.Status, http.StatusMethodNotAllowed)
+	assert(t, data.Details, "Invalid request type")
+	expectedMethods := strings.Join(methods, " or ")
+	assert(t, data.Message, fmt.Sprintf("Expected %s", expectedMethods))
+}
+
+func checkNon200(t *testing.T, data ErrorResponse, msg, endpoint string) {
+	t.Helper()
+	assert(t, data.Status, http.StatusSeeOther)
+	assert(t, data.Message, msg)
+	assert(t, data.Details, fmt.Sprintf("An error occurred on the %s endpoint", endpoint))
+}
+
+type FakeGitManager struct {
+	RemoteUrl   string
+	BranchName  string
+	ProjectName string
+	Namespace   string
+}
+
+func (f FakeGitManager) RefreshProjectInfo(remote string) error {
+	return nil
+}
+
+func (f FakeGitManager) GetCurrentBranchNameFromNativeGitCmd() (string, error) {
+	return f.BranchName, nil
+}
+
+func (f FakeGitManager) GetLatestCommitOnRemote(remote string, branchName string) (string, error) {
+	return "", nil
+}
+
+func (f FakeGitManager) GetProjectUrlFromNativeGitCmd(string) (url string, err error) {
+	return f.RemoteUrl, nil
+}