Fix IDE commit to use start_ref

**Why?**
The branch HEAD could be changed since the
IDE was opened. This leads to user's unintentionally
creating commits that overwrite other changes.

https://gitlab.com/gitlab-org/gitlab-ce/issues/59023

app/assets/javascripts/ide/services/index.js

@@ -56,7 +56,13 @@ export default {
     return Api.branchSingle(projectId, currentBranchId);
   },
   commit(projectId, payload) {
-    return Api.commitMultiple(projectId, payload);
+    // Currently the `commit` endpoint does not support `start_sha` so we
+    // have to make the request in the FE. This is not ideal and will be
+    // resolved soon. https://gitlab.com/gitlab-org/gitlab-ce/issues/59023
+    const { branch, start_sha: ref } = payload;
+    const branchPromise = ref ? Api.createBranch(projectId, { ref, branch }) : Promise.resolve();
+
+    return branchPromise.then(() => Api.commitMultiple(projectId, payload));
   },
   getFiles(projectUrl, branchId) {
     const url = `${projectUrl}/files/${branchId}`;

app/assets/javascripts/ide/stores/modules/commit/actions.js

@@ -123,6 +123,7 @@ export const commitChanges = ({ commit, state, getters, dispatch, rootState, roo
         getters,
         state,
         rootState,
+        rootGetters,
       });
 
       return service.commit(rootState.currentProjectId, payload);

app/assets/javascripts/ide/stores/utils.js

@@ -135,7 +135,14 @@ export const getCommitFiles = stagedFiles =>
     });
   }, []);
 
-export const createCommitPayload = ({ branch, getters, newBranch, state, rootState }) => ({
+export const createCommitPayload = ({
+  branch,
+  getters,
+  newBranch,
+  state,
+  rootState,
+  rootGetters,
+}) => ({
   branch,
   commit_message: state.commitMessage || getters.preBuiltCommitMessage,
   actions: getCommitFiles(rootState.stagedFiles).map(f => ({
@@ -146,7 +153,7 @@ export const createCommitPayload = ({ branch, getters, newBranch, state, rootSta
     encoding: f.base64 ? 'base64' : 'text',
     last_commit_id: newBranch || f.deleted || f.prevPath ? undefined : f.lastCommitSha,
   })),
-  start_branch: newBranch ? rootState.currentBranchId : undefined,
+  start_sha: newBranch ? rootGetters.lastCommit.short_id : undefined,
 });
 
 export const createNewMergeRequestUrl = (projectUrl, source, target) =>

changelogs/unreleased/59023-fix-web-ide-creating-branches-off-new-commits.yml

+---
+title: Fix IDE commit using latest ref in branch and overriding contents
+merge_request: 29769
+author:
+type: fixed

spec/frontend/ide/services/index_spec.js

+import services from '~/ide/services';
+import Api from '~/api';
+
+jest.mock('~/api');
+
+const TEST_PROJECT_ID = 'alice/wonderland';
+const TEST_BRANCH = 'master-patch-123';
+const TEST_COMMIT_SHA = '123456789';
+
+describe('IDE services', () => {
+  describe('commit', () => {
+    let payload;
+
+    beforeEach(() => {
+      payload = {
+        branch: TEST_BRANCH,
+        commit_message: 'Hello world',
+        actions: [],
+        start_sha: undefined,
+      };
+
+      Api.createBranch.mockReturnValue(Promise.resolve());
+      Api.commitMultiple.mockReturnValue(Promise.resolve());
+    });
+
+    describe.each`
+      startSha           | shouldCreateBranch
+      ${undefined}       | ${false}
+      ${TEST_COMMIT_SHA} | ${true}
+    `('when start_sha is $startSha', ({ startSha, shouldCreateBranch }) => {
+      beforeEach(() => {
+        payload.start_sha = startSha;
+
+        return services.commit(TEST_PROJECT_ID, payload);
+      });
+
+      if (shouldCreateBranch) {
+        it('should create branch', () => {
+          expect(Api.createBranch).toHaveBeenCalledWith(TEST_PROJECT_ID, {
+            ref: TEST_COMMIT_SHA,
+            branch: TEST_BRANCH,
+          });
+        });
+      } else {
+        it('should not create branch', () => {
+          expect(Api.createBranch).not.toHaveBeenCalled();
+        });
+      }
+
+      it('should commit', () => {
+        expect(Api.commitMultiple).toHaveBeenCalledWith(TEST_PROJECT_ID, payload);
+      });
+    });
+  });
+});

spec/javascripts/ide/stores/modules/commit/actions_spec.js

@@ -7,6 +7,8 @@ import consts from '~/ide/stores/modules/commit/constants';
 import { commitActionTypes } from '~/ide/constants';
 import { resetStore, file } from 'spec/ide/helpers';
 
+const TEST_COMMIT_SHA = '123456789';
+
 describe('IDE commit module actions', () => {
   beforeEach(() => {
     spyOn(router, 'push');
@@ -136,6 +138,9 @@ describe('IDE commit module actions', () => {
         branches: {
           master: {
             workingReference: '',
+            commit: {
+              short_id: TEST_COMMIT_SHA,
+            },
           },
         },
       };
@@ -236,6 +241,9 @@ describe('IDE commit module actions', () => {
         branches: {
           master: {
             workingReference: '1',
+            commit: {
+              short_id: TEST_COMMIT_SHA,
+            },
           },
         },
       };
@@ -244,7 +252,7 @@ describe('IDE commit module actions', () => {
         ...file('changed'),
         type: 'blob',
         active: true,
-        lastCommitSha: '123456789',
+        lastCommitSha: TEST_COMMIT_SHA,
       };
       store.state.stagedFiles.push(f);
       store.state.changedFiles = [
@@ -303,7 +311,7 @@ describe('IDE commit module actions', () => {
                   previous_path: undefined,
                 },
               ],
-              start_branch: 'master',
+              start_sha: TEST_COMMIT_SHA,
             });
 
             done();
@@ -326,11 +334,11 @@ describe('IDE commit module actions', () => {
                   file_path: jasmine.anything(),
                   content: undefined,
                   encoding: jasmine.anything(),
-                  last_commit_id: '123456789',
+                  last_commit_id: TEST_COMMIT_SHA,
                   previous_path: undefined,
                 },
               ],
-              start_branch: undefined,
+              start_sha: undefined,
             });
 
             done();

spec/javascripts/ide/stores/utils_spec.js

@@ -132,7 +132,7 @@ describe('Multi-file store utils', () => {
             previous_path: undefined,
           },
         ],
-        start_branch: undefined,
+        start_sha: undefined,
       });
     });
 
@@ -187,7 +187,7 @@ describe('Multi-file store utils', () => {
             previous_path: undefined,
           },
         ],
-        start_branch: undefined,
+        start_sha: undefined,
       });
     });
   });