Add description for intl-test-helper using TSDoc

tests/helpers/intl-test-helper.tsx

@@ -1,7 +1,6 @@
 // Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
 // See LICENSE.txt for license information.
 
-import PropTypes from 'prop-types';
 import React, {
     ReactElement,
     ExoticComponent,
@@ -30,6 +29,12 @@ export const defaultIntl = createIntl({
     textComponent: 'span',
 });
 
+/**
+ * Attempts to unwrap if wrapped in React.forwardRef
+ *
+ * @param element - the component element that might be wrapped in React.forwardRef.
+ * @returns cloned instance of wrapped element if it's forwardRef, otherwise just element.
+ */
 function unwrapForwardRef<WrappedComponentElement extends ReactElement>(element: ReactElement): WrappedComponentElement {
     const {type, props} = element as ReactElement<any, ExoticComponent>;
     if (type.$$typeof && type.$$typeof === Symbol.for('react.forward_ref')) {
@@ -57,31 +62,42 @@ interface ShallowWithIntlOptions extends ShallowRendererProps {
     intl?: IntlShape;
 }
 
+/**
+ * Shallow renders a react component which use injectIntl.
+ *
+ * @param element - An instance of {@link IntlInjectedElement}
+ * @param options - Extra options for Enzyme's {@link enzyme#shallow | `shallow()`}
+ */
 export function shallowWithIntl<T extends IntlInjectedElement>(element: T, options?: ShallowWithIntlOptions) {
     const {intl = defaultIntl, ...shallowOptions} = options || {};
 
     // eslint-disable-next-line no-param-reassign
     element = unwrapForwardRef<T>(element);
+
     if (!isIntlInjectedElement(element)) {
         throw new Error('shallowWithIntl() allows only components wrapped by injectIntl() HOC. Use shallow() instead.');
     }
 
     return shallow(
-
-        // Unwrap injectIntl
         <element.type.WrappedComponent
             intl={intl}
             {...element.props}
         />,
-
-        // Override options
         shallowOptions,
     );
 }
 
 interface MountWithIntlOptions extends MountRendererProps {
     intl?: IntlShape;
 }
+
+/**
+ * Mounts and renders a react component
+ * and provide context for {@link react-intl#useIntl | `useIntl()`}, `<Formatted.../>` and etc.
+ *
+ * @param element - An instance of any ReactElement containing elements use react-intl inside.
+ * @param options - Extra options for Enzyme's {@link enzyme#mount | `mount()`}
+ */
 export function mountWithIntl<T extends ReactElement | IntlInjectedElement>(element: T, options?: MountWithIntlOptions) {
     const {intl = defaultIntl, ...mountOptions} = options || {};
 
@@ -96,16 +112,9 @@ export function mountWithIntl<T extends ReactElement | IntlInjectedElement>(elem
         />
     ) : element;
 
-    return mount(
-        newElement,
-
-        // For useIntl, <Formatted.../>
-        {
-            wrappingComponent: IntlProvider,
-            wrappingComponentProps: {...intl},
-
-            // Override options
-            ...mountOptions,
-        },
-    );
+    return mount(newElement, {
+        wrappingComponent: IntlProvider,
+        wrappingComponentProps: {...intl},
+        ...mountOptions,
+    });
 }