Function render

packages/react-refresh/src/__tests__/ReactFreshIntegration-test.js:131–174

(source)

    ['TypeScript syntax', executeTypescript, testTypeScript],
  ])('%s', (language, execute, runTest) => {
    async function render(source) {
      const Component = execute(source);
      await act(() => {
        root.render(<Component />);
      });
      // Module initialization shouldn't be counted as a hot update.
      expect(ReactFreshRuntime.performReactRefresh()).toBe(null);
    }

    async function patch(source) {
      const prevExports = exportsObj;
      execute(source);
      const nextExports = exportsObj;

      // Check if exported families have changed.
      // (In a real module system we'd do this for *all* exports.)
      // For example, this can happen if you convert a class to a function.
      // Or if you wrap something in a HOC.
      const didExportsChange =
        ReactFreshRuntime.getFamilyByType(prevExports.default) !==
        ReactFreshRuntime.getFamilyByType(nextExports.default);
      if (didExportsChange) {
        // In a real module system, we would propagate such updates upwards,
        // and re-execute modules that imported this one. (Just like if we edited them.)
        // This makes adding/removing/renaming exports re-render references to them.
        // Here, we'll just force a re-render using the newer type to emulate this.
        const NextComponent = nextExports.default;
        await act(() => {
          root.render(<NextComponent />);
        });
      }
      await act(() => {
        const result = ReactFreshRuntime.performReactRefresh();
        if (!didExportsChange) {
          // Normally we expect that some components got updated in our tests.
          expect(result).not.toBe(null);
        } else {
          // However, we have tests where we convert functions to classes,
          // and in those cases it's expected nothing would get updated.
          // (Instead, the export change branch above would take care of it.)
        }
      });
      expect(ReactFreshRuntime._getMountedRootCount()).toBe(1);
    }

    runTest(render, patch);
  });