Resolve "Cannot update Epic is_fixed columns alone in API"

doc/api/epics.md

@@ -126,7 +126,12 @@ Example response:
 
 ## New epic
 
-Creates a new epic
+Creates a new epic.
+
+NOTE: **Note:**
+Starting with GitLab [11.3][ee-6448], `start_date` and `end_date` should no longer be assigned
+directly, as they now represent composite values. You can configure it via the `*_is_fixed` and
+`*_fixed` fields instead.
 
 ```
 POST /groups/:id/epics
@@ -138,8 +143,10 @@ POST /groups/:id/epics
 | `title`             | string           | yes        | The title of the epic |
 | `labels`            | string           | no         | The comma separated list of labels |
 | `description`       | string           | no         | The description of the epic  |
-| `start_date`        | string           | no         | The start date of the epic  |
-| `end_date`          | string.          | no         | The end date of the epic |
+| `start_date_is_fixed` | boolean        | no         | Whether start date should be sourced from `start_date_fixed` or from milestones (since 11.3) |
+| `start_date_fixed`  | string           | no         | The fixed start date of an epic (since 11.3) |
+| `due_date_is_fixed` | boolean          | no         | Whether due date should be sourced from `due_date_fixed` or from milestones (since 11.3) |
+| `due_date_fixed`    | string           | no         | The fixed due date of an epic (since 11.3) |
 
 ```bash
 curl --header POST "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/groups/1/epics?title=Epic&description=Epic%20description
@@ -179,9 +186,12 @@ Example response:
 
 ## Update epic
 
-Updates an epic
+Updates an epic.
 
-Note that after [11.3][ee-6448], `start_date` and `end_date` should no longer be updated directly, as they now represent composite values. Users can configure via `_is_fixed` and `_fixed` fields instead.
+NOTE: **Note:**
+Starting with GitLab [11.3][ee-6448], `start_date` and `end_date` should no longer be assigned
+directly, as they now represent composite values. You can configure it via the `*_is_fixed` and
+`*_fixed` fields instead.
 
 ```
 PUT /groups/:id/epics/:epic_iid
@@ -194,9 +204,9 @@ PUT /groups/:id/epics/:epic_iid
 | `title`             | string           | no         | The title of an epic |
 | `description`       | string           | no         | The description of an epic  |
 | `labels`            | string           | no         | The comma separated list of labels |
-| `start_date_is_fixed` | boolean        | no         | Whether start date should be sourced from `start_date_fixed` (since 11.3) |
+| `start_date_is_fixed` | boolean        | no         | Whether start date should be sourced from `start_date_fixed` or from milestones (since 11.3) |
 | `start_date_fixed`  | string           | no         | The fixed start date of an epic (since 11.3) |
-| `due_date_is_fixed` | boolean          | no         | Whether due date should be sourced from `due_date_fixed` (since 11.3) |
+| `due_date_is_fixed` | boolean          | no         | Whether due date should be sourced from `due_date_fixed` or from milestones (since 11.3) |
 | `due_date_fixed`    | string           | no         | The fixed due date of an epic (since 11.3) |
 
 ```bash

ee/lib/api/epics.rb

@@ -112,7 +112,7 @@ module API
         optional :end_date, as: :due_date_fixed, type: String, desc: 'The due date of an epic'
         optional :due_date_is_fixed, type: Boolean, desc: 'Indicates due date should be sourced from due_date_fixed field not the issue milestones'
         optional :labels, type: String, desc: 'Comma-separated list of label names'
-        at_least_one_of :title, :description, :start_date_fixed, :due_date_fixed, :labels
+        at_least_one_of :title, :description, :start_date_fixed, :start_date_is_fixed, :due_date_fixed, :due_date_is_fixed, :labels
       end
       put ':id/(-/)epics/:epic_iid' do
         authorize_can_admin!

ee/spec/requests/api/epics_spec.rb

@@ -197,7 +197,15 @@ describe API::Epics do
 
   describe 'POST /groups/:id/epics' do
     let(:url) { "/groups/#{group.path}/epics" }
-    let(:params) { { title: 'new epic', description: 'epic description', labels: 'label1' } }
+    let(:params) do
+      {
+        title: 'new epic',
+        description: 'epic description',
+        labels: 'label1',
+        due_date_fixed: '2018-07-17',
+        due_date_is_fixed: true
+      }
+    end
 
     it_behaves_like 'error requests'
 
@@ -236,6 +244,10 @@ describe API::Epics do
 
           expect(epic.title).to eq('new epic')
           expect(epic.description).to eq('epic description')
+          expect(epic.start_date_fixed).to eq(nil)
+          expect(epic.start_date_is_fixed).to be_falsey
+          expect(epic.due_date_fixed).to eq(Date.new(2018, 7, 17))
+          expect(epic.due_date_is_fixed).to eq(true)
           expect(epic.labels.first.title).to eq('label1')
         end
 
@@ -308,6 +320,8 @@ describe API::Epics do
           expect(result.start_date).to eq(Date.new(2018, 7, 17))
           expect(result.start_date_fixed).to eq(Date.new(2018, 7, 17))
           expect(result.start_date_is_fixed).to eq(true)
+          expect(result.due_date_fixed).to eq(nil)
+          expect(result.due_date_is_fixed).to be_falsey
         end
 
         context 'when deprecated start_date and end_date params are present' do
@@ -323,6 +337,19 @@ describe API::Epics do
             expect(result.due_date_fixed).to eq(new_due_date)
           end
         end
+
+        context 'when updating start_date_is_fixed by itself' do
+          let(:epic) { create(:epic, :use_fixed_dates, group: group) }
+          let(:new_start_date) { epic.start_date + 1.day }
+          let(:new_due_date) { epic.end_date + 1.day }
+          let!(:params) { { start_date_is_fixed: false } }
+
+          it 'updates start_date_is_fixed' do
+            result = epic.reload
+
+            expect(result.start_date_is_fixed).to eq(false)
+          end
+        end
       end
     end
   end