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

@@ -892,7 +892,7 @@ 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']);
 
       // A discrete event forces the passive effect to be flushed --
       // updateCount(1) happens first, so 2 wins.
@@ -907,8 +907,8 @@ 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')]);
@@ -956,7 +956,7 @@ 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 +973,8 @@ 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')]);