fix: Ensure that initial selected index never goes below 0

Author: danez

src/components/Tabs.js

@@ -99,7 +99,7 @@ For more information about controlled and uncontrolled mode of react-tabs see th
  };
 
  if (newState.mode === MODE_UNCONTROLLED) {
- const maxTabIndex = getTabsCount(props.children) - 1;
+ const maxTabIndex = Math.max(0, getTabsCount(props.children) - 1);
  let selectedIndex = null;
 
  if (state.selectedIndex != null) {

src/components/__tests__/Tabs-test.js

@@ -541,4 +541,21 @@ describe('<Tabs />', () => {
  expect(firstTab).toHaveFocus();
  assertTabSelected(1);
  });
+
+ test('should render first tab once tabs are available', () => {
+ const { rerender } = render(<Tabs></Tabs>);
+
+ rerender(
+ <Tabs>
+ <TabList>
+ <Tab data-testid="tab1">Tab1</Tab>
+ <Tab data-testid="tab2">Tab2</Tab>
+ </TabList>
+ <TabPanel data-testid="panel1">Hello Tab1</TabPanel>
+ <TabPanel data-testid="panel2">Hello Tab2</TabPanel>
+ </Tabs>,
+ );
+
+ assertTabSelected(1);
+ });
 });