chore: Add an indicator for incoming emails (#1112)

app/javascript/shared/constants/contentType.js

@@ -0,0 +1,3 @@
+export const CONTENT_TYPES = {
+  INCOMING_EMAIL: 'incoming_email',
+};

app/javascript/shared/mixins/contentTypeMixin.js

@@ -0,0 +1,9 @@
+import { CONTENT_TYPES } from '../constants/contentType';
+
+export default {
+  computed: {
+    isEmailContentType() {
+      return this.contentType === CONTENT_TYPES.INCOMING_EMAIL;
+    },
+  },
+};

app/javascript/shared/mixins/specs/contentTypeMixin.spec.js

@@ -0,0 +1,32 @@
+import { shallowMount } from '@vue/test-utils';
+import contentTypeMixin from '../contentTypeMixin';
+
+describe('contentTypeMixin', () => {
+  it('returns true if contentType is incoming_email', () => {
+    const Component = {
+      render() {},
+      mixins: [contentTypeMixin],
+      computed: {
+        contentType() {
+          return 'incoming_email';
+        },
+      },
+    };
+    const wrapper = shallowMount(Component);
+    expect(wrapper.vm.isEmailContentType).toBe(true);
+  });
+
+  it('returns false if contentType is not incoming_email', () => {
+    const Component = {
+      render() {},
+      mixins: [contentTypeMixin],
+      computed: {
+        contentType() {
+          return 'input_select';
+        },
+      },
+    };
+    const wrapper = shallowMount(Component);
+    expect(wrapper.vm.isEmailContentType).toBe(false);
+  });
+});