[Fix] shallow: do not call cDM unexpectedly

Fixes #1765. Fixes #1766.

Author: koba04

packages/enzyme-test-suite/test/ReactWrapper-spec.jsx

@@ -5196,5 +5196,35 @@ describeWithDOM('mount', () => {
       expect(spy).to.have.property('callCount', 1);
       expect(wrapper.state('foo')).to.equal('update');
     });
+
+    it('should not call `componentDidMount` twice when a child component is created', () => {
+      class Foo extends React.Component {
+        constructor(props) {
+          super(props);
+          this.state = {
+            foo: 'init',
+          };
+        }
+
+        componentDidMount() {}
+
+        render() {
+          return (
+            <div>
+              <button onClick={() => this.setState({ foo: 'update2' })}>
+                click
+              </button>
+              {this.state.foo}
+            </div>
+          );
+        }
+      }
+      const spy = sinon.spy(Foo.prototype, 'componentDidMount');
+
+      const wrapper = mount(<Foo />);
+      expect(spy).to.have.property('callCount', 1);
+      wrapper.find('button').prop('onClick')();
+      expect(spy).to.have.property('callCount', 1);
+    });
   });
 });

packages/enzyme-test-suite/test/ShallowWrapper-spec.jsx

@@ -4994,6 +4994,36 @@ describe('shallow', () => {
         expect(spy).to.have.property('callCount', 1);
         expect(wrapper.state('foo')).to.equal('update');
       });
+
+      it('should not call `componentDidMount` twice when a child component is created', () => {
+        class Foo extends React.Component {
+          constructor(props) {
+            super(props);
+            this.state = {
+              foo: 'init',
+            };
+          }
+
+          componentDidMount() {}
+
+          render() {
+            return (
+              <div>
+                <button onClick={() => this.setState({ foo: 'update2' })}>
+                  click
+                </button>
+                {this.state.foo}
+              </div>
+            );
+          }
+        }
+        const spy = sinon.spy(Foo.prototype, 'componentDidMount');
+
+        const wrapper = shallow(<Foo />);
+        expect(spy).to.have.property('callCount', 1);
+        wrapper.find('button').prop('onClick')();
+        expect(spy).to.have.property('callCount', 1);
+      });
     });
 
     describeIf(is('>= 16'), 'support getSnapshotBeforeUpdate', () => {
@@ -5054,6 +5084,36 @@ describe('shallow', () => {
       expect(spy).to.have.property('callCount', 0);
     });
 
+    it('should be able to call `componentDidMount` directly when disableLifecycleMethods is true', () => {
+      class Table extends React.Component {
+        render() {
+          return (<table />);
+        }
+      }
+
+      class MyComponent extends React.Component {
+        constructor(props) {
+          super(props);
+          this.state = {
+            showTable: false,
+          };
+        }
+
+        componentDidMount() {
+          this.setState({ showTable: true });
+        }
+
+        render() {
+          const { showTable } = this.state;
+          return (<div>{showTable ? <Table /> : null}</div>);
+        }
+      }
+      const wrapper = shallow(<MyComponent />, { disableLifecycleMethods: true });
+      expect(wrapper.find(Table).length).to.equal(0);
+      wrapper.instance().componentDidMount();
+      expect(wrapper.find(Table).length).to.equal(1);
+    });
+
     it('should call shouldComponentUpdate when disableLifecycleMethods flag is true', () => {
       const spy = sinon.spy();
       class Foo extends React.Component {

packages/enzyme/src/ShallowWrapper.js

@@ -168,37 +168,38 @@ class ShallowWrapper {
     const adapter = getAdapter(options);
     const lifecycles = getAdapterLifecycles(adapter);
 
-    let renderedNode;
+    // mounting a ShallowRender component
     if (!root) {
       privateSet(this, ROOT, this);
       privateSet(this, UNRENDERED, nodes);
       const renderer = adapter.createRenderer({ mode: 'shallow', ...options });
       privateSet(this, RENDERER, renderer);
       this[RENDERER].render(nodes, options.context);
-      renderedNode = this[RENDERER].getNode();
+      const renderedNode = this[RENDERER].getNode();
       privateSetNodes(this, getRootNode(renderedNode));
+      privateSet(this, OPTIONS, options);
+
+      const { instance } = renderedNode;
+      if (instance && !options.disableLifecycleMethods) {
+        // Ensure to call componentDidUpdate when instance.setState is called
+        if (lifecycles.componentDidUpdate.onSetState && !instance[SET_STATE]) {
+          privateSet(instance, SET_STATE, instance.setState);
+          instance.setState = (...args) => this.setState(...args);
+        }
+
+        if (typeof instance.componentDidMount === 'function') {
+          this[RENDERER].batchedUpdates(() => {
+            instance.componentDidMount();
+          });
+        }
+      }
+    // creating a child component through enzyme's ShallowWrapper APIs.
     } else {
       privateSet(this, ROOT, root);
       privateSet(this, UNRENDERED, null);
       privateSet(this, RENDERER, root[RENDERER]);
       privateSetNodes(this, nodes);
-      renderedNode = this[RENDERER].getNode();
-    }
-    privateSet(this, OPTIONS, root ? root[OPTIONS] : options);
-
-    const { instance } = renderedNode;
-    if (instance && !options.disableLifecycleMethods) {
-      // Ensure to call componentDidUpdate when instance.setState is called
-      if (lifecycles.componentDidUpdate.onSetState && !instance[SET_STATE]) {
-        privateSet(instance, SET_STATE, instance.setState);
-        instance.setState = (...args) => this.setState(...args);
-      }
-
-      if (typeof instance.componentDidMount === 'function') {
-        this[RENDERER].batchedUpdates(() => {
-          instance.componentDidMount();
-        });
-      }
+      privateSet(this, OPTIONS, root[OPTIONS]);
     }
   }