Feat: Adds Ability to Merge MR (#147)

This adds the ability to merge an MR from within `gitlab.nvim` directly. If the reviewer is open, it'll be closed automatically. Users may configure whether they'd like to squash commits on the merge, as well as whether they'd like to delete the original source branch on a merge.

If squashing, users are prompted to provide an optional custom squash message for the squash commit.

cmd/merge_test.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"errors"
+	"net/http"
+	"testing"
+
+	"github.com/xanzy/go-gitlab"
+)
+
+func acceptAndMergeFn(pid interface{}, mergeRequest int, opt *gitlab.AcceptMergeRequestOptions, options ...gitlab.RequestOptionFunc) (*gitlab.MergeRequest, *gitlab.Response, error) {
+	return &gitlab.MergeRequest{}, makeResponse(http.StatusOK), nil
+}
+
+func acceptAndMergeFnErr(pid interface{}, mergeRequest int, opt *gitlab.AcceptMergeRequestOptions, options ...gitlab.RequestOptionFunc) (*gitlab.MergeRequest, *gitlab.Response, error) {
+	return nil, nil, errors.New("Some error from Gitlab")
+}
+
+func acceptAndMergeNon200(pid interface{}, mergeRequest int, opt *gitlab.AcceptMergeRequestOptions, options ...gitlab.RequestOptionFunc) (*gitlab.MergeRequest, *gitlab.Response, error) {
+	return nil, makeResponse(http.StatusSeeOther), nil
+}
+
+func TestAcceptAndMergeHandler(t *testing.T) {
+	t.Run("Accepts and merges a merge request", func(t *testing.T) {
+		request := makeRequest(t, http.MethodPost, "/merge", AcceptMergeRequestRequest{})
+		server, _ := createRouterAndApi(fakeClient{acceptAndMergeFn: acceptAndMergeFn})
+		data := serveRequest(t, server, request, SuccessResponse{})
+		assert(t, data.Message, "MR merged successfully")
+		assert(t, data.Status, http.StatusOK)
+	})
+
+	t.Run("Disallows non-POST methods", func(t *testing.T) {
+		request := makeRequest(t, http.MethodGet, "/merge", AcceptMergeRequestRequest{})
+		server, _ := createRouterAndApi(fakeClient{acceptAndMergeFn: acceptAndMergeFn})
+		data := serveRequest(t, server, request, ErrorResponse{})
+		checkBadMethod(t, *data, http.MethodPost)
+	})
+
+	t.Run("Handles errors from Gitlab client", func(t *testing.T) {
+		request := makeRequest(t, http.MethodPost, "/merge", AcceptMergeRequestRequest{})
+		server, _ := createRouterAndApi(fakeClient{acceptAndMergeFn: acceptAndMergeFnErr})
+		data := serveRequest(t, server, request, ErrorResponse{})
+		checkErrorFromGitlab(t, *data, "Could not merge MR")
+	})
+
+	t.Run("Handles non-200s from Gitlab client", func(t *testing.T) {
+		request := makeRequest(t, http.MethodPost, "/merge", AcceptMergeRequestRequest{})
+		server, _ := createRouterAndApi(fakeClient{acceptAndMergeFn: acceptAndMergeNon200})
+		data := serveRequest(t, server, request, ErrorResponse{})
+		checkNon200(t, *data, "Could not merge MR", "/merge")
+	})
+}