Fix ListViewMock unique key error (#14894)

Summary:
Add key prop to renderHeader and renderFooter in ListViewMock.
Fix unique key error when using jest snapshots.

It closes #12762
Pull Request resolved: https://github.com/facebook/react-native/pull/14894

Reviewed By: TheSavior

Differential Revision: D13396721

Pulled By: cpojer

fbshipit-source-id: 5bbcb8157e3cd98fe07f2a037e1dbc06ab599c87

Libraries/Lists/ListView/__mocks__/ListViewMock.js

@@ -24,34 +24,51 @@ class ListViewMock extends React.Component<$FlowFixMeProps> {
      * Flow. */
     renderScrollComponent: props => <ScrollView {...props} />,
   };
+
   componentDidMount() {
     ListViewMock.latestRef = this;
   }
+
   render() {
     const {dataSource, renderFooter, renderHeader} = this.props;
-    const rows = [renderHeader && renderHeader()];
-    const allRowIDs = dataSource.rowIdentities;
-    for (let sectionIdx = 0; sectionIdx < allRowIDs.length; sectionIdx++) {
-      const sectionID = dataSource.sectionIdentities[sectionIdx];
-      const rowIDs = allRowIDs[sectionIdx];
-      for (let rowIdx = 0; rowIdx < rowIDs.length; rowIdx++) {
-        const rowID = rowIDs[rowIdx];
-        // Row IDs are only unique in a section
-        rows.push(
+    let rows = [
+      renderHeader && (
         <StaticRenderer
-            key={'section_' + sectionID + '_row_' + rowID}
+          key="renderHeader"
+          shouldUpdate={true}
+          render={renderHeader}
+        />
+      ),
+    ];
+
+    const dataSourceRows = dataSource.rowIdentities.map(
+      (rowIdentity, rowIdentityIndex) => {
+        const sectionID = dataSource.sectionIdentities[rowIdentityIndex];
+        return rowIdentity.map((row, rowIndex) => (
+          <StaticRenderer
+            key={'section_' + sectionID + '_row_' + rowIndex}
             shouldUpdate={true}
             render={this.props.renderRow.bind(
               null,
-              dataSource.getRowData(sectionIdx, rowIdx),
+              dataSource.getRowData(rowIdentityIndex, rowIndex),
               sectionID,
-              rowID,
+              row,
             )}
+          />
+        ));
+      },
+    );
+
+    rows = [...rows, ...dataSourceRows];
+    renderFooter &&
+      rows.push(
+        <StaticRenderer
+          key="renderFooter"
+          shouldUpdate={true}
+          render={renderFooter}
         />,
       );
-      }
-    }
-    renderFooter && rows.push(renderFooter());
+
     return this.props.renderScrollComponent({...this.props, children: rows});
   }
   static DataSource = ListViewDataSource;