Fix epic add existing issue form

Clicking on the "Add an existing issue" button in an epic
showed the Linked Issues part of the form which was incorrect.
This commit fixes this so it is not shown in this scenario.

ee/app/assets/javascripts/related_issues/components/add_issuable_form.vue

@@ -33,6 +33,11 @@ export default {
       required: false,
       default: () => ({}),
     },
+    isLinkedIssueBlock: {
+      type: Boolean,
+      required: false,
+      default: false,
+    },
     isSubmitting: {
       type: Boolean,
       required: false,
@@ -83,9 +88,6 @@ export default {
     };
   },
   computed: {
-    isIssue() {
-      return this.issuableType === issuableTypesMap.ISSUE;
-    },
     isSubmitButtonDisabled() {
       return (
         (this.inputValue.length === 0 && this.pendingReferences.length === 0) || this.isSubmitting
@@ -126,7 +128,7 @@ export default {
 
 <template>
   <form @submit.prevent="onFormSubmit">
-    <template v-if="isIssue">
+    <template v-if="isLinkedIssueBlock">
       <gl-form-group
         :label="__('The current issue')"
         label-for="linked-issue-type-radio"

ee/app/assets/javascripts/related_issues/components/related_issues_block.vue

@@ -169,6 +169,7 @@ export default {
           class="js-add-related-issues-form-area card-body bordered-box bg-white"
         >
           <add-issuable-form
+            :is-linked-issue-block="true"
             :is-submitting="isSubmitting"
             :issuable-type="issuableType"
             :input-value="inputValue"

ee/spec/features/epics/epic_issues_spec.rb

@@ -244,5 +244,14 @@ describe 'Epic Issues', :js do
         expect(page).to have_selector('li.js-item-type-issue', count: 3)
       end
     end
+
+    it 'user does not see the linked issues part of the form when they click "Add an existing issue"' do
+      find(".related-items-tree-container .js-add-epics-issues-button").click
+      find('.related-items-tree-container .js-add-epics-issues-button .dropdown-item', text: 'Add an existing issue').click
+
+      expect(page).not_to have_content("The current issue")
+      expect(page).not_to have_content("is blocked by")
+      expect(page).not_to have_content("the following issue(s)")
+    end
   end
 end

ee/spec/javascripts/issuable/related_issues/components/add_issuable_form_spec.js

@@ -113,6 +113,41 @@ describe('AddIssuableForm', () => {
         });
       });
 
+      it('does not show radio inputs', () => {
+        expect(findRadioInputs(wrapper).length).toBe(0);
+      });
+    });
+
+    describe('when issuable type is "epic"', () => {
+      beforeEach(() => {
+        wrapper = shallowMount(AddIssuableForm, {
+          propsData: {
+            inputValue: '',
+            issuableType: issuableTypesMap.EPIC,
+            pathIdSeparator,
+            pendingReferences: [],
+          },
+        });
+      });
+
+      it('does not show radio inputs', () => {
+        expect(findRadioInputs(wrapper).length).toBe(0);
+      });
+    });
+
+    describe('when it is a Linked Issues form', () => {
+      beforeEach(() => {
+        wrapper = mount(AddIssuableForm, {
+          propsData: {
+            inputValue: '',
+            isLinkedIssueBlock: true,
+            issuableType: issuableTypesMap.ISSUE,
+            pathIdSeparator,
+            pendingReferences: [],
+          },
+        });
+      });
+
       it('shows radio inputs to allow categorisation of blocking issues', () => {
         expect(findRadioInputs(wrapper).length).toBeGreaterThan(0);
       });
@@ -202,22 +237,5 @@ describe('AddIssuableForm', () => {
         });
       });
     });
-
-    describe('when issuable type is "epic"', () => {
-      beforeEach(() => {
-        wrapper = shallowMount(AddIssuableForm, {
-          propsData: {
-            inputValue: '',
-            issuableType: issuableTypesMap.EPIC,
-            pathIdSeparator,
-            pendingReferences: [],
-          },
-        });
-      });
-
-      it('does not show radio inputs', () => {
-        expect(findRadioInputs(wrapper).length).toBe(0);
-      });
-    });
   });
 });