Clear staged changes _before_ redirection

Any local changes in WebIDE should be cleared _before_ redirecting
to the new merge request page. Earlier, it was happening just after
redirection, which causes onbeforeunload event to trigger and warns the
user that his unsaved changes will be lost, when in fact there are no
unsaved changes at this point.

The test for this case was falsely passing. I have modified it to
ensure that it always fails in the absence of this change.

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

@@ -152,6 +152,14 @@ export const commitChanges = ({ commit, state, getters, dispatch, rootState, roo
         branch: getters.branchName,
       })
         .then(() => {
+          commit(rootTypes.CLEAR_STAGED_CHANGES, null, { root: true });
+
+          commit(rootTypes.CLEAR_REPLACED_FILES, null, { root: true });
+
+          setTimeout(() => {
+            commit(rootTypes.SET_LAST_COMMIT_MSG, '', { root: true });
+          }, 5000);
+
           if (state.shouldCreateMR) {
             const { currentProject } = rootGetters;
             const targetBranch = getters.isCreatingNewBranch
@@ -164,14 +172,6 @@ export const commitChanges = ({ commit, state, getters, dispatch, rootState, roo
               { root: true },
             );
           }
-
-          commit(rootTypes.CLEAR_STAGED_CHANGES, null, { root: true });
-
-          commit(rootTypes.CLEAR_REPLACED_FILES, null, { root: true });
-
-          setTimeout(() => {
-            commit(rootTypes.SET_LAST_COMMIT_MSG, '', { root: true });
-          }, 5000);
         })
         .then(() => {
           if (rootGetters.lastOpenedFile) {

changelogs/unreleased/30881-webide-mr-confirmation.yml

+---
+title: 'Fix Issue: WebIDE asks for confirmation to leave the page when committing
+  and creating a new MR'
+merge_request: 17671
+author:
+type: fixed

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

@@ -473,18 +473,16 @@ describe('IDE commit module actions', () => {
         });
 
         it('resets changed files before redirecting', done => {
+          visitUrl = visitUrl.and.callFake(() => {
+            expect(store.state.stagedFiles.length).toBe(0);
+            done();
+          });
+
           spyOn(eventHub, '$on');
 
           store.state.commit.commitAction = '3';
 
-          store
-            .dispatch('commit/commitChanges')
-            .then(() => {
-              expect(store.state.stagedFiles.length).toBe(0);
-
-              done();
-            })
-            .catch(done.fail);
+          store.dispatch('commit/commitChanges').catch(done.fail);
         });
       });
     });