diff --git a/test/core.js b/test/core.js
index 19f66a3d..673e1dcb 100644
--- a/test/core.js
+++ b/test/core.js
@@ -273,8 +273,8 @@ test( "jQuery.expr.pseudos aliases", function( assert ) {
 } );
 
 TestManager.runIframeTest( "old pre-3.0 jQuery", "old-jquery.html",
-	function( logOutput, assert ) {
+	function( assert, jQuery, window, document, log ) {
 		assert.expect( 1 );
 
-		assert.ok( /jQuery 3/.test( logOutput ), "logged: " + logOutput );
+		assert.ok( /jQuery 3/.test( log ), "logged: " + log );
 	} );
diff --git a/test/event-props.html b/test/event-props.html
index 5d08cc70..29a68910 100644
--- a/test/event-props.html
+++ b/test/event-props.html
@@ -8,17 +8,13 @@
 	<script src="testinit.js"></script>
 	<script>
 		TestManager.loadProject( "jquery", "git" );
-		// Close this script tag so file will load
 	</script>
+	<script src="iframeTest.js"></script>
 	<script>
 		jQuery.noConflict();
 		TestManager.loadProject( "jquery-migrate", "dev", true );
-		// Close this script tag so file will load
 	</script>
 	<script>
-		jQuery.migrateMute = true;
-		jQuery.migrateReset();
-
 		function dispatchEvent( elem, type ) {
 			var e = document.createEvent( "HTMLEvents" );
 			e.initEvent( type, true, true );
@@ -57,7 +53,7 @@
 					jQuery.event.props.length === 0 &&
 					jQuery.event.fixHooks[ "excite" ].props.length === 0;
 
-				parent.TestManager.iframeCallback( worked );
+				startIframeTest( worked );
 			} );
 
 			dispatchEvent( div, "excite" );
diff --git a/test/event.js b/test/event.js
index b35654e6..ade59cac 100644
--- a/test/event.js
+++ b/test/event.js
@@ -107,20 +107,19 @@ test( "custom ready", function() {
 } );
 
 TestManager.runIframeTest( "document ready", "ready-event.html",
-	function( fired, warnings, assert ) {
-		assert.expect( 2 );
+	function( assert, jQuery, window, document, log ) {
+		assert.expect( 1 );
 
-		assert.ok( fired, "ready event fired" );
-		assert.equal( warnings.length, 1, "warnings: " + JSON.stringify( warnings ) );
+		assert.equal( jQuery.migrateWarnings.length, 1, "warnings: " +
+			JSON.stringify( jQuery.migrateWarnings ) );
 	} );
 
-if ( jQuery.event.addProp ) {
-
-	// Do this as iframe because there is no way to undo prop addition
-	TestManager.runIframeTest( "jQuery.event.props and fixHooks", "event-props.html",
-		function( worked, assert ) {
-			assert.expect( 1 );
+// Do this as iframe because there is no way to undo prop addition
+TestManager.runIframeTest( "jQuery.event.props and fixHooks", "event-props.html",
+	function( assert, jQuery, window, document, log, worked ) {
+		assert.expect( 2 );
 
-			assert.ok( worked, "hooks were installed" );
-		} );
-}
+		assert.ok( worked, "hooks were installed" );
+		assert.equal( jQuery.migrateWarnings.length, 2, "warnings: " +
+			JSON.stringify( jQuery.migrateWarnings ) );
+	} );
diff --git a/test/iframeTest.js b/test/iframeTest.js
new file mode 100644
index 00000000..6f9c793a
--- /dev/null
+++ b/test/iframeTest.js
@@ -0,0 +1,29 @@
+/*
+ * Iframe-based unit tests support
+ * Load this file immediately after jQuery, before jQuery Migrate
+ */
+
+// Warning messages are available to parent test in jQuery.migrateWarnings
+jQuery.migrateMute = true;
+
+// Support: IE9 only (no console at times)
+if ( !window.console ) {
+	window.console = {};
+}
+
+// Capture output so the test in the parent window can inspect it, and so the
+// initialization for the iframe doesn't show another Migrate startup header.
+var logOutput = "";
+
+window.console.log = function() {
+	logOutput += Array.prototype.join.call( arguments, " " ) + "\n";
+};
+
+// Callback gets ( jQuery, window, document, log [, startIframe args ] )
+window.startIframeTest = function() {
+	var args = Array.prototype.slice.call( arguments );
+
+	// Note: jQuery may be undefined if page did not load it
+	args.unshift( window.jQuery, window, document, logOutput );
+	window.parent.TestManager.iframeCallback.apply( null, args );
+};
diff --git a/test/old-jquery.html b/test/old-jquery.html
index 7a22d00b..dc3dd7f3 100644
--- a/test/old-jquery.html
+++ b/test/old-jquery.html
@@ -3,31 +3,18 @@
 <head>
 	<meta charset="utf-8">
 	<title>jQuery Migrate old-jQuery initialization test</title>
-	<script>
-		// Capture log output to ensure we warned on old jQuery
-		var logOutput = "";
-
-		// Support: IE9 only (no console at times)
-		if ( !window.console ) {
-			window.console = {};
-		}
-
-		window.console.log = function() {
-			logOutput += Array.prototype.join.call( arguments, " " ) + "\n";
-		};
-	</script>
 
 	<!-- Load older jQuery, then jquery-migrate plugin file based on URL -->
 	<script src="./data/jquery-2.2.3.js"></script>
+	<script src="iframeTest.js"></script>
 	<script src="testinit.js"></script>
 	<script>
 		jQuery.noConflict();
 		TestManager.loadProject( "jquery-migrate", "dev", true );
-		// Close this script tag so file will load
 	</script>
 	<script>
 		// Should have logged during initialization
-		parent.TestManager.iframeCallback( logOutput );
+		startIframeTest();
 	</script>
 </head>
 <body>
diff --git a/test/ready-event.html b/test/ready-event.html
index f2512b22..78751fa1 100644
--- a/test/ready-event.html
+++ b/test/ready-event.html
@@ -8,18 +8,16 @@
 	<script src="testinit.js"></script>
 	<script>
 		TestManager.loadProject( "jquery", "git" );
-		// Close this script tag so file will load
 	</script>
+	<script src="iframeTest.js"></script>
 	<script>
 		jQuery.noConflict();
 		TestManager.loadProject( "jquery-migrate", "dev", true );
-		// Close this script tag so file will load
 	</script>
 	<script>
-		jQuery.migrateMute = true;
-		jQuery.migrateReset();
+		// This should warn when the handler runs
 		jQuery( document ).on( "ready", function() {
-			parent.TestManager.iframeCallback( true, jQuery.migrateWarnings );
+			startIframeTest();
 		} );
 	</script>
 </head>
diff --git a/test/testinit.js b/test/testinit.js
index 23e978e6..3f848b28 100644
--- a/test/testinit.js
+++ b/test/testinit.js
@@ -78,7 +78,7 @@ TestManager = {
 			self.iframeCallback = function() {
 				var args = Array.prototype.slice.call( arguments );
 
-				args.push( assert );
+				args.unshift( assert );
 
 				setTimeout( function() {
 					self.iframeCallback = undefined;