test(useNodesINitialized): add test

examples/nextjs/cypress/components/hooks/useNodesInitialized.cy.tsx

@@ -0,0 +1,68 @@
+import ReactFlow, { useNodesInitialized } from 'reactflow';
+
+import { nodes } from '../../fixtures/simpleflow';
+import ControlledFlow from '../../support/ControlledFlow';
+
+describe('useNodesInitialized.cy.tsx', () => {
+  it('returns false for no nodes', () => {
+    const initSpy = cy.spy().as('initSpy');
+
+    cy.mount(
+      <ReactFlow nodes={[]}>
+        <HookHelperComponent onChange={initSpy} />
+      </ReactFlow>
+    );
+
+    cy.get('@initSpy').should('to.be.calledOnce');
+    cy.get('@initSpy').should('have.been.calledWith', false);
+  });
+
+  it('returns false without onNodesChange', () => {
+    const initSpy = cy.spy().as('initSpy');
+
+    cy.mount(
+      <ReactFlow nodes={nodes}>
+        <HookHelperComponent onChange={initSpy} />
+      </ReactFlow>
+    );
+
+    cy.get('@initSpy').should('to.be.calledOnce');
+    cy.get('@initSpy').should('have.be.calledWith', false);
+  });
+
+  it('returns true for defaultNodes', () => {
+    const initSpy = cy.spy().as('initSpy');
+
+    cy.mount(
+      <ReactFlow defaultNodes={nodes}>
+        <HookHelperComponent onChange={initSpy} />
+      </ReactFlow>
+    );
+
+    cy.get('@initSpy').should('have.been.calledWith', false);
+    cy.get('@initSpy').should('have.been.calledWith', true);
+  });
+
+  it('returns true for nodes + onNodesChange', () => {
+    const initSpy = cy.spy().as('initSpy');
+
+    cy.mount(
+      <ControlledFlow initialNodes={nodes}>
+        <HookHelperComponent onChange={initSpy} />
+      </ControlledFlow>
+    );
+
+    cy.get('@initSpy').should('have.been.calledWith', false);
+    cy.get('@initSpy').should('have.been.calledWith', true);
+  });
+});
+
+// test specific helpers
+
+function HookHelperComponent({ onChange }: { onChange: (init: boolean) => void }) {
+  const initialized = useNodesInitialized();
+
+  onChange(initialized);
+
+  return null;
+}