unify deprecated/unsafe lifecycle warnings, pass tests

- redoes #15431 from scratch, taking on the feedback there
- unifies the messaging between "deprecated" and UNSAFE_ lifecycle messages. It reorganizes ReactStrictModeWarnings.js to capture and flush all the lifecycle warnings in one procedure each.
- matches the warning from ReactPartialRenderer to match the above change
- passes all the tests
- this also turns on `warnAboutDeprecatedLifecycles` for the test renderer. I think we missed doing so it previously. In a future PR, I'll remove the feature flag altogether.
- this DOES NOT do the same treatment for context warnings, I'll do that in another PR too

Author: threepointone

packages/react-dom/src/__tests__/ReactComponentLifeCycle-test.js

@@ -709,9 +709,9 @@ describe('ReactComponentLifeCycle', () => {
       );
     }).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated',
-        'componentWillReceiveProps is deprecated',
-        'componentWillUpdate is deprecated',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
@@ -748,9 +748,9 @@ describe('ReactComponentLifeCycle', () => {
       );
     }).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated',
-        'componentWillReceiveProps is deprecated',
-        'componentWillUpdate is deprecated',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
@@ -815,7 +815,10 @@ describe('ReactComponentLifeCycle', () => {
         {withoutStack: true},
       );
     }).toLowPriorityWarnDev(
-      ['componentWillMount is deprecated', 'componentWillUpdate is deprecated'],
+      [
+        'componentWillMount has been renamed',
+        'componentWillUpdate has been renamed',
+      ],
       {withoutStack: true},
     );
 
@@ -863,7 +866,7 @@ describe('ReactComponentLifeCycle', () => {
           'https://fb.me/react-async-component-lifecycle-hooks',
         {withoutStack: true},
       );
-    }).toLowPriorityWarnDev(['componentWillMount is deprecated'], {
+    }).toLowPriorityWarnDev(['componentWillMount has been renamed'], {
       withoutStack: true,
     });
 
@@ -887,7 +890,7 @@ describe('ReactComponentLifeCycle', () => {
           'https://fb.me/react-async-component-lifecycle-hooks',
         {withoutStack: true},
       );
-    }).toLowPriorityWarnDev(['componentWillReceiveProps is deprecated'], {
+    }).toLowPriorityWarnDev(['componentWillReceiveProps has been renamed'], {
       withoutStack: true,
     });
   });
@@ -921,7 +924,10 @@ describe('ReactComponentLifeCycle', () => {
         {withoutStack: true},
       );
     }).toLowPriorityWarnDev(
-      ['componentWillMount is deprecated', 'componentWillUpdate is deprecated'],
+      [
+        'componentWillMount has been renamed',
+        'componentWillUpdate has been renamed',
+      ],
       {withoutStack: true},
     );
 
@@ -967,7 +973,7 @@ describe('ReactComponentLifeCycle', () => {
           'https://fb.me/react-async-component-lifecycle-hooks',
         {withoutStack: true},
       );
-    }).toLowPriorityWarnDev(['componentWillMount is deprecated'], {
+    }).toLowPriorityWarnDev(['componentWillMount has been renamed'], {
       withoutStack: true,
     });
 
@@ -990,7 +996,7 @@ describe('ReactComponentLifeCycle', () => {
           'https://fb.me/react-async-component-lifecycle-hooks',
         {withoutStack: true},
       );
-    }).toLowPriorityWarnDev(['componentWillReceiveProps is deprecated'], {
+    }).toLowPriorityWarnDev(['componentWillReceiveProps has been renamed'], {
       withoutStack: true,
     });
   });
@@ -1130,9 +1136,9 @@ describe('ReactComponentLifeCycle', () => {
       ReactDOM.render(<MyComponent foo="bar" />, div),
     ).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated',
-        'componentWillReceiveProps is deprecated',
-        'componentWillUpdate is deprecated',
+        'componentWillMount has been renamed',
+        'componentWillReceiveProps has been renamed',
+        'componentWillUpdate has been renamed',
       ],
       {withoutStack: true},
     );
@@ -1403,22 +1409,35 @@ describe('ReactComponentLifeCycle', () => {
       ReactDOM.render(<MyComponent x={1} />, container),
     ).toLowPriorityWarnDev(
       [
-        'componentWillMount is deprecated and will be removed in the next major version. ' +
-          'Use componentDidMount instead. As a temporary workaround, ' +
-          'you can rename to UNSAFE_componentWillMount.' +
-          '\n\nPlease update the following components: MyComponent',
-        'componentWillReceiveProps is deprecated and will be removed in the next major version. ' +
-          'Use static getDerivedStateFromProps instead.' +
-          '\n\nPlease update the following components: MyComponent',
-        'componentWillUpdate is deprecated and will be removed in the next major version. ' +
-          'Use componentDidUpdate instead. As a temporary workaround, ' +
-          'you can rename to UNSAFE_componentWillUpdate.' +
-          '\n\nPlease update the following components: MyComponent',
+        /* eslint-disable max-len */
+        `Warning: componentWillMount has been renamed, and is not recommended for use. See https://fb.me/react-async-component-lifecycle-hooks for details.
+
+* Move code from componentWillMount to componentDidMount (preferred in most cases) or the constructor.
+* Rename componentWillMount to UNSAFE_componentWillMount to suppress this warning in non-strict mode. In React 17.x, only the UNSAFE_ name will work.
+* To rename all deprecated lifecycles to their new names, you can run \`npx react-codemod rename-unsafe-lifecycles /path/to/code\`.
+
+Please update the following components: MyComponent`,
+        `Warning: componentWillReceiveProps has been renamed, and is not recommended for use. See https://fb.me/react-async-component-lifecycle-hooks for details.
+
+* Move data fetching code or side effects from componentWillReceiveProps to componentDidUpdate.
+* If you're updating state whenever props change, refactor your code to use memoization techniques, or move it to static getDerivedStateFromProps. Learn more at: https://fb.me/react-derived-state
+* Rename componentWillReceiveProps to UNSAFE_componentWillReceiveProps to suppress this warning in non-strict mode. In React 17.x, only the UNSAFE_ name will work.
+* To rename all deprecated lifecycles to their new names, you can run \`npx react-codemod rename-unsafe-lifecycles /path/to/code\`.
+
+Please update the following components: MyComponent`,
+        `Warning: componentWillUpdate has been renamed, and is not recommended for use. See https://fb.me/react-async-component-lifecycle-hooks for details.
+
+* Move data fetching code or side effects from componentWillUpdate to componentDidUpdate.
+* Rename componentWillUpdate to UNSAFE_componentWillUpdate to suppress this warning in non-strict mode. In React 17.x, only the UNSAFE_ name will work.
+* To rename all deprecated lifecycles to their new names, you can run \`npx react-codemod rename-unsafe-lifecycles /path/to/code\`.
+
+Please update the following components: MyComponent`,
+        /* eslint-enable max-len */
       ],
       {withoutStack: true},
     );
 
-    // Dedupe check (update and instantiate new
+    // Dedupe check (update and instantiate new)
     ReactDOM.render(<MyComponent x={2} />, container);
     ReactDOM.render(<MyComponent key="new" x={1} />, container);
   });

packages/react-dom/src/__tests__/ReactDOMServerLifecycles-test.js

@@ -229,7 +229,7 @@ describe('ReactDOMServerLifecycles', () => {
 
     expect(() =>
       ReactDOMServer.renderToString(<Component />),
-    ).toLowPriorityWarnDev('componentWillMount() is deprecated', {
+    ).toLowPriorityWarnDev('componentWillMount has been renamed', {
       withoutStack: true,
     });
     expect(log).toEqual(['componentWillMount', 'UNSAFE_componentWillMount']);
@@ -286,10 +286,9 @@ describe('ReactDOMServerLifecycles', () => {
 
     expect(() =>
       ReactDOMServer.renderToString(<Component />),
-    ).toLowPriorityWarnDev(
-      'Component: componentWillMount() is deprecated and will be removed in the next major version.',
-      {withoutStack: true},
-    );
+    ).toLowPriorityWarnDev('componentWillMount has been renamed', {
+      withoutStack: true,
+    });
   });
 
   it('should warn about deprecated lifecycle hooks', () => {
@@ -302,11 +301,9 @@ describe('ReactDOMServerLifecycles', () => {
 
     expect(() =>
       ReactDOMServer.renderToString(<Component />),
-    ).toLowPriorityWarnDev(
-      'Warning: Component: componentWillMount() is deprecated and will be removed ' +
-        'in the next major version.',
-      {withoutStack: true},
-    );
+    ).toLowPriorityWarnDev('componentWillMount has been renamed', {
+      withoutStack: true,
+    });
 
     // De-duped
     ReactDOMServer.renderToString(<Component />);

packages/react-dom/src/__tests__/ReactServerRenderingHydration-test.js

@@ -362,20 +362,16 @@ describe('ReactDOMServerHydration', () => {
     const element = document.createElement('div');
     expect(() => {
       element.innerHTML = ReactDOMServer.renderToString(markup);
-    }).toLowPriorityWarnDev(
-      ['componentWillMount() is deprecated and will be removed'],
-      {withoutStack: true},
-    );
+    }).toLowPriorityWarnDev(['componentWillMount has been renamed'], {
+      withoutStack: true,
+    });
     expect(element.textContent).toBe('Hi');
 
     expect(() => {
-      expect(() => ReactDOM.hydrate(markup, element)).toWarnDev(
-        'Please update the following components to use componentDidMount instead: ComponentWithWarning',
-      );
-    }).toLowPriorityWarnDev(
-      ['componentWillMount is deprecated and will be removed'],
-      {withoutStack: true},
-    );
+      ReactDOM.hydrate(markup, element);
+    }).toLowPriorityWarnDev(['componentWillMount has been renamed'], {
+      withoutStack: true,
+    });
     expect(element.textContent).toBe('Hi');
   });
 

packages/react-dom/src/server/ReactPartialRenderer.js

@@ -572,13 +572,12 @@ function resolve(
             if (!didWarnAboutDeprecatedWillMount[componentName]) {
               lowPriorityWarning(
                 false,
-                '%s: componentWillMount() is deprecated and will be ' +
-                  'removed in the next major version. Read about the motivations ' +
-                  'behind this change: ' +
-                  'https://fb.me/react-async-component-lifecycle-hooks' +
-                  '\n\n' +
-                  'As a temporary workaround, you can rename to ' +
-                  'UNSAFE_componentWillMount instead.',
+                // keep this warning in sync with ReactStrictModeWarning.js
+                'componentWillMount has been renamed, and is not recommended for use. ' +
+                  'See https://fb.me/react-async-component-lifecycle-hooks for details.\n\n' +
+                  '* Move code from componentWillMount to componentDidMount (preferred in most cases) ' +
+                  'or the constructor.\n' +
+                  '\nPlease update the following components: %s',
                 componentName,
               );
               didWarnAboutDeprecatedWillMount[componentName] = true;

packages/react-reconciler/src/ReactFiberClassComponent.js

@@ -806,19 +806,14 @@ function mountClassInstance(
     }
 
     if (workInProgress.mode & StrictMode) {
-      ReactStrictModeWarnings.recordUnsafeLifecycleWarnings(
-        workInProgress,
-        instance,
-      );
-
       ReactStrictModeWarnings.recordLegacyContextWarning(
         workInProgress,
         instance,
       );
     }
 
     if (warnAboutDeprecatedLifecycles) {
-      ReactStrictModeWarnings.recordDeprecationWarnings(
+      ReactStrictModeWarnings.recordUnsafeLifecycleWarnings(
         workInProgress,
         instance,
       );

packages/react-reconciler/src/ReactFiberWorkLoop.js

@@ -2247,11 +2247,10 @@ function checkForNestedUpdates() {
 
 function flushRenderPhaseStrictModeWarningsInDEV() {
   if (__DEV__) {
-    ReactStrictModeWarnings.flushPendingUnsafeLifecycleWarnings();
     ReactStrictModeWarnings.flushLegacyContextWarning();
 
     if (warnAboutDeprecatedLifecycles) {
-      ReactStrictModeWarnings.flushPendingDeprecationWarnings();
+      ReactStrictModeWarnings.flushPendingUnsafeLifecycleWarnings();
     }
   }
 }