Fix dependency graph with new nodes

Signed-off-by: Oliver Sand <oliver.sand@sda-se.com>

.changeset/thirty-seas-bathe.md

@@ -0,0 +1,5 @@
+---
+'@backstage/core-components': patch
+---
+
+Handle changes to nodes passed into `<DependencyGraph>` correctly.

packages/core-components/src/components/DependencyGraph/DependencyGraph.test.tsx

@@ -49,6 +49,28 @@ describe('<DependencyGraph />', () => {
     expect(queryAllByTestId(LABEL_TEST_ID)).toHaveLength(0);
   });
 
+  it('update render if already referenced nodes are added later', async () => {
+    const { getByText, queryAllByTestId, findAllByTestId, rerender } = render(
+      <DependencyGraph nodes={nodes.slice(0, 2)} edges={edges} />,
+    );
+
+    let renderedNodes = await findAllByTestId(NODE_TEST_ID);
+    expect(renderedNodes).toHaveLength(2);
+    expect(getByText(nodes[0].id)).toBeInTheDocument();
+    expect(getByText(nodes[1].id)).toBeInTheDocument();
+    expect(queryAllByTestId(EDGE_TEST_ID)).toHaveLength(2);
+    expect(queryAllByTestId(LABEL_TEST_ID)).toHaveLength(0);
+
+    rerender(<DependencyGraph nodes={nodes} edges={edges} />);
+
+    renderedNodes = await findAllByTestId(NODE_TEST_ID);
+    expect(renderedNodes).toHaveLength(3);
+    expect(getByText(nodes[0].id)).toBeInTheDocument();
+    expect(getByText(nodes[1].id)).toBeInTheDocument();
+    expect(queryAllByTestId(EDGE_TEST_ID)).toHaveLength(2);
+    expect(queryAllByTestId(LABEL_TEST_ID)).toHaveLength(0);
+  });
+
   it('renders edge labels if present', async () => {
     const labeledEdges = [
       { ...edges[0], label: 'first' },

packages/core-components/src/components/DependencyGraph/DependencyGraph.tsx

@@ -171,7 +171,7 @@ export function DependencyGraph({
         .nodes()
         .find(nodeId => node.id === nodeId);
 
-      if (existingNode) {
+      if (existingNode && graph.current.node(existingNode)) {
         const { width, height, x, y } = graph.current.node(existingNode);
         graph.current.setNode(existingNode, { ...node, width, height, x, y });
       } else {