a better message, consistent with the state update one.

Author: threepointone

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

@@ -74,10 +74,10 @@ describe('ReactDOMHooks', () => {
       expect(container2.textContent).toBe('4');
       expect(container3.textContent).toBe('6');
     }).toWarnDev([
-      'Your test just caused an effect from Example1',
-      'Your test just caused an effect from Example2',
-      'Your test just caused an effect from Example1',
-      'Your test just caused an effect from Example2',
+      'An update to Example1 ran an effect',
+      'An update to Example2 ran an effect',
+      'An update to Example1 ran an effect',
+      'An update to Example2 ran an effect',
     ]);
   });
 

packages/react-reconciler/src/ReactFiberWorkLoop.js

@@ -2434,7 +2434,7 @@ export function warnIfNotCurrentlyActingEffectsInDEV(fiber: Fiber): void {
     if (ReactCurrentActingRendererSigil.current !== ReactActingRendererSigil) {
       warningWithoutStack(
         false,
-        'Your test just caused an effect from %s, but was not wrapped in act(...).\n\n' +
+        'An update to %s ran an effect, but was not wrapped in act(...).\n\n' +
           'When testing, code that causes React state updates should be ' +
           'wrapped into act(...):\n\n' +
           'act(() => {\n' +

packages/react-reconciler/src/__tests__/ReactHooks-test.internal.js

@@ -1800,7 +1800,7 @@ describe('ReactHooks', () => {
       globalListener();
       globalListener();
     }).toWarnDev([
-      'Your test just caused an effect from C',
+      'An update to C ran an effect',
       'An update to C inside a test was not wrapped in act',
       'An update to C inside a test was not wrapped in act',
       // Note: should *not* warn about updates on unmounted component.

packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.internal.js

@@ -674,7 +674,7 @@ describe('ReactHooksWithNoopRenderer', () => {
         expect(Scheduler).toFlushAndYield(['Passive effect']);
         expect(ReactNoop.getChildren()).toEqual([span('Passive')]);
       });
-      // exiting act calls flushePassiveEffects(), but there none are left with flush.
+      // exiting act calls flushPassiveEffects(), but there are none left to flush.
       expect(Scheduler).toHaveYielded([]);
     });
 
@@ -885,14 +885,13 @@ describe('ReactHooksWithNoopRenderer', () => {
 
       // we explicitly wait for missing act() warnings here since
       // it's a lot harder to simulate this condition inside an act scope
-      // todo - is this ok?
       expect(() => {
         ReactNoop.render(<Counter count={0} />, () =>
           Scheduler.yieldValue('Sync effect'),
         );
         expect(Scheduler).toFlushAndYieldThrough(['Count: 0', 'Sync effect']);
         expect(ReactNoop.getChildren()).toEqual([span('Count: 0')]);
-      }).toWarnDev(['Your test just caused an effect from Counter']);
+      }).toWarnDev(['An update to Counter ran an effect']);
 
       // A discrete event forces the passive effect to be flushed --
       // updateCount(1) happens first, so 2 wins.
@@ -907,8 +906,8 @@ describe('ReactHooksWithNoopRenderer', () => {
       expect(() => {
         expect(Scheduler).toFlushAndYield(['Count: 2']);
       }).toWarnDev([
-        'Your test just caused an effect from Counter',
-        'Your test just caused an effect from Counter',
+        'An update to Counter ran an effect',
+        'An update to Counter ran an effect',
       ]);
 
       expect(ReactNoop.getChildren()).toEqual([span('Count: 2')]);
@@ -943,7 +942,6 @@ describe('ReactHooksWithNoopRenderer', () => {
       const tracingEvent = {id: 0, name: 'hello', timestamp: 0};
       // we explicitly wait for missing act() warnings here since
       // it's a lot harder to simulate this condition inside an act scope
-      // todo - is this ok?
       expect(() => {
         SchedulerTracing.unstable_trace(
           tracingEvent.name,
@@ -956,7 +954,7 @@ describe('ReactHooksWithNoopRenderer', () => {
         );
         expect(Scheduler).toFlushAndYieldThrough(['Count: 0', 'Sync effect']);
         expect(ReactNoop.getChildren()).toEqual([span('Count: 0')]);
-      }).toWarnDev(['Your test just caused an effect from Counter']);
+      }).toWarnDev(['An update to Counter ran an effect']);
 
       expect(onInteractionScheduledWorkCompleted).toHaveBeenCalledTimes(0);
 
@@ -973,8 +971,8 @@ describe('ReactHooksWithNoopRenderer', () => {
       expect(() => {
         expect(Scheduler).toFlushAndYield(['Count: 2']);
       }).toWarnDev([
-        'Your test just caused an effect from Counter',
-        'Your test just caused an effect from Counter',
+        'An update to Counter ran an effect',
+        'An update to Counter ran an effect',
       ]);
 
       expect(ReactNoop.getChildren()).toEqual([span('Count: 2')]);