Port fast-forward MR widget states from EE

See https://gitlab.com/gitlab-org/gitlab-ce/issues/20076

7 files changed, 157 insertions, 83 deletions

diff --git a/app/assets/javascripts/vue_merge_request_widget/components/mr_widget_status_icon.js b/app/assets/javascripts/vue_merge_request_widget/components/mr_widget_status_icon.js
index 703f3a56a34..3cbcbdd52c5 100644
--- a/app/assets/javascripts/vue_merge_request_widget/components/mr_widget_status_icon.js
+++ b/app/assets/javascripts/vue_merge_request_widget/components/mr_widget_status_icon.js
@@ -26,6 +26,7 @@ export default {
       <ci-icon v-else :status="statusObj" />
       <button
         v-if="showDisabledButton"
+        ref="mergeButton"
         type="button"
         class="btn btn-success btn-sm"
         disabled="true">
diff --git a/app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_conflicts.js b/app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_conflicts.js
index f9cb79a0bc1..f2245a532f4 100644
--- a/app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_conflicts.js
+++ b/app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_conflicts.js
@@ -10,27 +10,40 @@ export default {
   },
   template: `
     <div class="mr-widget-body media">
-      <status-icon status="failed" showDisabledButton />
+      <status-icon
+        ref="statusIcon"
+        status="failed"
+        showDisabledButton />
       <div class="media-body space-children">
-        <span class="bold">
-          There are merge conflicts<span v-if="!mr.canMerge">.</span>
-          <span v-if="!mr.canMerge">
-            Resolve these conflicts or ask someone with write access to this repository to merge it locally
+        <template v-if="mr.ffOnlyEnabled">
+          <span class="bold">
+            Fast-forward merge is not possible.
+            To merge this request, first rebase locally
           </span>
-        </span>
-        <a
-          v-if="mr.canMerge && mr.conflictResolutionPath"
-          :href="mr.conflictResolutionPath"
-          class="btn btn-default btn-xs js-resolve-conflicts-button">
-          Resolve conflicts
-        </a>
-        <a
-          v-if="mr.canMerge"
-          class="btn btn-default btn-xs js-merge-locally-button"
-          data-toggle="modal"
-          href="#modal_merge_info">
-          Merge locally
-        </a>
+        </template>
+        <template v-else>
+          <span class="bold">
+            There are merge conflicts<span v-if="!mr.canMerge">.</span>
+            <span v-if="!mr.canMerge">
+              Resolve these conflicts or ask someone with write access to this repository to merge it locally
+            </span>
+          </span>
+          <a
+            v-if="mr.canMerge && mr.conflictResolutionPath"
+            ref="resolveConflictsButton"
+            :href="mr.conflictResolutionPath"
+            class="btn btn-default btn-xs">
+            Resolve conflicts
+          </a>
+          <a
+            v-if="mr.canMerge"
+            ref="mergeLocallyButton"
+            class="btn btn-default btn-xs"
+            data-toggle="modal"
+            href="#modal_merge_info">
+            Merge locally
+          </a>
+        </template>
       </div>
     </div>
   `,
diff --git a/app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_ready_to_merge.js b/app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_ready_to_merge.js
index ad709da51ee..e1c37add496 100644
--- a/app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_ready_to_merge.js
+++ b/app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_ready_to_merge.js
@@ -284,7 +284,14 @@ export default {
                 :mr="mr"
                 :is-merge-button-disabled="isMergeButtonDisabled" />
 
+              <span
+                v-if="mr.ffOnlyEnabled"
+                ref="fastForwardMessage">
+                Fast-forward merge without a merge commit
+              </span>
               <button
+                v-else
+                ref="modifyCommitMessageButton"
                 @click="toggleCommitMessageEditor"
                 :disabled="isMergeButtonDisabled"
                 class="btn btn-default btn-xs"
diff --git a/app/assets/javascripts/vue_merge_request_widget/stores/mr_widget_store.js b/app/assets/javascripts/vue_merge_request_widget/stores/mr_widget_store.js
index 29464662578..03969e33e97 100644
--- a/app/assets/javascripts/vue_merge_request_widget/stores/mr_widget_store.js
+++ b/app/assets/javascripts/vue_merge_request_widget/stores/mr_widget_store.js
@@ -57,6 +57,7 @@ export default class MergeRequestStore {
     this.onlyAllowMergeIfPipelineSucceeds = data.only_allow_merge_if_pipeline_succeeds || false;
     this.mergeWhenPipelineSucceeds = data.merge_when_pipeline_succeeds || false;
     this.mergePath = data.merge_path;
+    this.ffOnlyEnabled = data.ff_only_enabled;
     this.statusPath = data.status_path;
     this.emailPatchesPath = data.email_patches_path;
     this.plainDiffPath = data.plain_diff_path;
diff --git a/app/serializers/merge_request_entity.rb b/app/serializers/merge_request_entity.rb
index 1f5ce2ef58c..5f2700df692 100644
--- a/app/serializers/merge_request_entity.rb
+++ b/app/serializers/merge_request_entity.rb
@@ -17,7 +17,6 @@ class MergeRequestEntity < IssuableEntity
     merge_request.project.merge_requests_ff_only_enabled
   end
 
-
   # Events
   expose :merge_event, using: EventEntity
   expose :closed_event, using: EventEntity
diff --git a/spec/javascripts/vue_mr_widget/components/states/mr_widget_conflicts_spec.js b/spec/javascripts/vue_mr_widget/components/states/mr_widget_conflicts_spec.js
index 3b7b7d93662..d4b18703b25 100644
--- a/spec/javascripts/vue_mr_widget/components/states/mr_widget_conflicts_spec.js
+++ b/spec/javascripts/vue_mr_widget/components/states/mr_widget_conflicts_spec.js
@@ -2,17 +2,16 @@ import Vue from 'vue';
 import conflictsComponent from '~/vue_merge_request_widget/components/states/mr_widget_conflicts';
 
 const path = '/conflicts';
-const createComponent = () => {
+const createComponent = (customConfig = {}) => {
   const Component = Vue.extend(conflictsComponent);
 
+  const config = Object.assign({
+    mr: {},
+  }, customConfig);
+
   return new Component({
     el: document.createElement('div'),
-    propsData: {
-      mr: {
-        canMerge: true,
-        conflictResolutionPath: path,
-      },
-    },
+    propsData: config,
   });
 };
 
@@ -27,44 +26,78 @@ describe('MRWidgetConflicts', () => {
   });
 
   describe('template', () => {
-    it('should have correct elements', () => {
-      const el = createComponent().$el;
-      const resolveButton = el.querySelector('.js-resolve-conflicts-button');
-      const mergeButton = el.querySelector('.mr-widget-body .btn');
-      const mergeLocallyButton = el.querySelector('.js-merge-locally-button');
-
-      expect(el.textContent).toContain('There are merge conflicts');
-      expect(el.textContent).not.toContain('ask someone with write access');
-      expect(el.querySelector('.btn-success').disabled).toBeTruthy();
-      expect(resolveButton.textContent).toContain('Resolve conflicts');
-      expect(resolveButton.getAttribute('href')).toEqual(path);
-      expect(mergeButton.textContent).toContain('Merge');
-      expect(mergeLocallyButton.textContent).toContain('Merge locally');
+    describe('when allowed to merge', () => {
+      let vm;
+
+      beforeEach(() => {
+        vm = createComponent({
+          mr: {
+            canMerge: true,
+            conflictResolutionPath: path,
+          },
+        });
+      });
+
+      it('should tell you about conflicts without bothering other people', () => {
+        expect(vm.$el.textContent).toContain('There are merge conflicts');
+        expect(vm.$el.textContent).not.toContain('ask someone with write access');
+      });
+
+      it('should allow you to resolve the conflicts', () => {
+        const resolveButton = vm.$refs.resolveConflictsButton;
+
+        expect(resolveButton.textContent).toContain('Resolve conflicts');
+        expect(resolveButton.getAttribute('href')).toEqual(path);
+      });
+
+      it('should have merge buttons', () => {
+        const mergeButton = vm.$refs.statusIcon.$refs.mergeButton;
+        const mergeLocallyButton = vm.$refs.mergeLocallyButton;
+
+        expect(mergeButton.textContent).toContain('Merge');
+        expect(mergeButton.disabled).toBeTruthy();
+        expect(mergeButton.classList.contains('btn-success')).toBeTruthy();
+        expect(mergeLocallyButton.textContent).toContain('Merge locally');
+      });
     });
 
     describe('when user does not have permission to merge', () => {
       let vm;
 
       beforeEach(() => {
-        vm = createComponent();
-        vm.mr.canMerge = false;
+        vm = createComponent({
+          mr: {
+            canMerge: false,
+          },
+        });
       });
 
-      it('should show proper message', (done) => {
-        Vue.nextTick(() => {
-          expect(vm.$el.textContent).toContain('ask someone with write access');
-          done();
-        });
+      it('should show proper message', () => {
+        expect(vm.$el.textContent).toContain('ask someone with write access');
+      });
+
+      it('should not have action buttons', () => {
+        expect(vm.$refs.statusIcon.$refs.mergeButton).toBeDefined();
+        expect(vm.$refs.resolveConflictsButton).toBeUndefined();
+        expect(vm.$refs.mergeLocallyButton).toBeUndefined();
       });
+    });
+
+    describe('when fast-forward merge enabled', () => {
+      let vm;
 
-      it('should not have action buttons', (done) => {
-        Vue.nextTick(() => {
-          expect(vm.$el.querySelectorAll('.btn').length).toBe(1);
-          expect(vm.$el.querySelector('.js-resolve-conflicts-button')).toEqual(null);
-          expect(vm.$el.querySelector('.js-merge-locally-button')).toEqual(null);
-          done();
+      beforeEach(() => {
+        vm = createComponent({
+          mr: {
+            ffOnlyEnabled: true,
+          },
         });
       });
+
+      it('should tell you to rebase locally', () => {
+        expect(vm.$el.textContent).toContain('Fast-forward merge is not possible.');
+        expect(vm.$el.textContent).toContain('To merge this request, first rebase locally');
+      });
     });
   });
 });
diff --git a/spec/javascripts/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js b/spec/javascripts/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js
index 03a52f1f91c..f36b74c9e94 100644
--- a/spec/javascripts/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js
+++ b/spec/javascripts/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js
@@ -182,36 +182,6 @@ describe('MRWidgetReadyToMerge', () => {
         expect(vm.isMergeButtonDisabled).toBeTruthy();
       });
     });
-
-    describe('Remove source branch checkbox', () => {
-      describe('when user can merge but cannot delete branch', () => {
-        it('isRemoveSourceBranchButtonDisabled should be true', () => {
-          expect(vm.isRemoveSourceBranchButtonDisabled).toBe(true);
-        });
-
-        it('should be disabled in the rendered output', () => {
-          const checkboxElement = vm.$el.querySelector('#remove-source-branch-input');
-          expect(checkboxElement.getAttribute('disabled')).toBe('disabled');
-        });
-      });
-
-      describe('when user can merge and can delete branch', () => {
-        beforeEach(() => {
-          this.customVm = createComponent({
-            mr: { canRemoveSourceBranch: true },
-          });
-        });
-
-        it('isRemoveSourceBranchButtonDisabled should be false', () => {
-          expect(this.customVm.isRemoveSourceBranchButtonDisabled).toBe(false);
-        });
-
-        it('should be enabled in rendered output', () => {
-          const checkboxElement = this.customVm.$el.querySelector('#remove-source-branch-input');
-          expect(checkboxElement.getAttribute('disabled')).toBeNull();
-        });
-      });
-    });
   });
 
   describe('methods', () => {
@@ -467,4 +437,54 @@ describe('MRWidgetReadyToMerge', () => {
       });
     });
   });
+
+  describe('Remove source branch checkbox', () => {
+    describe('when user can merge but cannot delete branch', () => {
+      it('isRemoveSourceBranchButtonDisabled should be true', () => {
+        expect(vm.isRemoveSourceBranchButtonDisabled).toBe(true);
+      });
+
+      it('should be disabled in the rendered output', () => {
+        const checkboxElement = vm.$el.querySelector('#remove-source-branch-input');
+        expect(checkboxElement.getAttribute('disabled')).toBe('disabled');
+      });
+    });
+
+    describe('when user can merge and can delete branch', () => {
+      beforeEach(() => {
+        this.customVm = createComponent({
+          mr: { canRemoveSourceBranch: true },
+        });
+      });
+
+      it('isRemoveSourceBranchButtonDisabled should be false', () => {
+        expect(this.customVm.isRemoveSourceBranchButtonDisabled).toBe(false);
+      });
+
+      it('should be enabled in rendered output', () => {
+        const checkboxElement = this.customVm.$el.querySelector('#remove-source-branch-input');
+        expect(checkboxElement.getAttribute('disabled')).toBeNull();
+      });
+    });
+  });
+
+  describe('Commit message area', () => {
+    it('when using merge commits, should show "Modify commit message" button', () => {
+      const customVm = createComponent({
+        mr: { ffOnlyEnabled: false },
+      });
+
+      expect(customVm.$refs.fastForwardMessage).toBeUndefined();
+      expect(customVm.$refs.modifyCommitMessageButton).toBeDefined();
+    });
+
+    it('when fast-forward merge is enabled, only show fast-forward message', () => {
+      const customVm = createComponent({
+        mr: { ffOnlyEnabled: true },
+      });
+
+      expect(customVm.$refs.fastForwardMessage).toBeDefined();
+      expect(customVm.$refs.modifyCommitMessageButton).toBeUndefined();
+    });
+  });
 });