fix: ensures branches don't expand completely on first click (#47)

After the initial render with `initialDepth` set, clicking a node which
contained multiple sublevels would expand the entire subtree.

This was due to an unnecessary special case in the tree generation step,
which meant not all possible child nodes could be collapsed when the
tree was generated.

Author: bkrem

src/Tree/index.js

@@ -439,15 +439,7 @@ class Tree extends React.Component {
       .separation(
         (a, b) => (a.parent.id === b.parent.id ? separation.siblings : separation.nonSiblings),
       )
-      .children(d => {
-        if (initialDepth !== undefined && isInitialRenderForDataset) {
-          // If `initialDepth` is defined, a node's depth determines
-          // whether we append `children` on the first render.
-          return d.depth >= initialDepth ? null : d._children;
-        }
-        // Node's `collapsed` property determines appending of `children` for subsequent renders.
-        return d._collapsed ? null : d._children;
-      });
+      .children(d => (d._collapsed ? null : d._children));
 
     const rootNode = this.state.data[0];
     let nodes = tree.nodes(rootNode);

src/Tree/tests/index.test.js

@@ -286,6 +286,17 @@ describe('<Tree />', () => {
       const renderedComponent = shallow(<Tree data={mockTree_D1N2_D2N2} initialDepth={0} />);
       expect(renderedComponent.find(Node).length).toBe(1);
     });
+
+    it('increases tree depth by no more than 1 level when a node is expanded after initialising to `initialDepth`', () => {
+      const renderedComponent = mount(<Tree data={mockTree_D1N2_D2N2} initialDepth={0} />);
+      expect(renderedComponent.find(Node).length).toBe(1);
+      renderedComponent
+        .find(Node)
+        .first()
+        .find('circle')
+        .simulate('click');
+      expect(renderedComponent.find(Node).length).toBe(3);
+    });
   });
 
   describe('zoomable', () => {