Merge pull request react-bootstrap#1127 from taion/deprecation-warning-once

Only issue each deprecation warning once

Author: jquense

src/CollapsibleMixin.js

@@ -2,8 +2,6 @@ import React from 'react';
 import TransitionEvents from './utils/TransitionEvents';
 import deprecationWarning from './utils/deprecationWarning';
 
-let warned = false;
-
 const CollapsibleMixin = {
 
   propTypes: {
@@ -25,10 +23,7 @@ const CollapsibleMixin = {
   },
 
   componentWillMount(){
-    if ( !warned ){
-      deprecationWarning('CollapsibleMixin', 'Collapse Component');
-      warned = true;
-    }
+    deprecationWarning('CollapsibleMixin', 'Collapse Component');
   },
 
   componentWillUpdate(nextProps, nextState){

src/FadeMixin.js

@@ -17,14 +17,9 @@ function getElementsAndSelf (root, classes){
   return els;
 }
 
-let warned = false;
-
 export default {
   componentWillMount(){
-    if ( !warned ){
-      deprecationWarning('FadeMixin', 'Fade Component');
-      warned = true;
-    }
+    deprecationWarning('FadeMixin', 'Fade Component');
   },
 
   _fadeIn() {

src/utils/deprecationWarning.js

@@ -1,11 +1,19 @@
 import warning from 'react/lib/warning';
 
+const warned = {};
+
 export default function deprecationWarning(oldname, newname, link) {
+  const warnKey = `${oldname}\n${newname}`;
+  if (warned[warnKey]) {
+    return;
+  }
+
   let message = `${oldname} is deprecated. Use ${newname} instead.`;
 
   if (link) {
     message += `\nYou can read more about it at ${link}`;
   }
 
   warning(false, message);
+  warned[warnKey] = true;
 }

test/utils/deprecationWarningSpec.js

@@ -0,0 +1,16 @@
+import deprecationWarning from '../../src/utils/deprecationWarning';
+
+describe('deprecationWarning', function () {
+  it('warns exactly once', function () {
+    // console.warn has already been stubbed out by test setup.
+
+    deprecationWarning('foo', 'bar');
+    expect(console.warn).to.have.been.calledOnce;
+
+    deprecationWarning('foo', 'bar');
+    expect(console.warn).to.have.been.calledOnce;
+
+    // Reset the stub to avoid unhandled warnings.
+    console.warn.reset();
+  });
+});