Add a test for ObjC methods imported with counted-by

Author: DougGregor

test/Interop/ObjC/swiftify-import/counted-by-in-class.swift

@@ -0,0 +1,29 @@
+// REQUIRES: swift_feature_SafeInteropWrappers
+
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: %target-swift-ide-test -plugin-path %swift-plugin-dir -I %t/Inputs -enable-experimental-feature SafeInteropWrappers -print-module -module-to-print=Method -source-filename=x | %FileCheck %s
+// RUN: %target-swift-frontend -plugin-path %swift-plugin-dir -I %t/Inputs -enable-experimental-feature SafeInteropWrappers %t/method.swift -dump-macro-expansions -typecheck -verify
+
+// REQUIRES: objc_interop
+
+// CHECK: class Foo {
+// CHECK:  func bar(_ p: UnsafeMutableBufferPointer<Float>)
+
+//--- Inputs/module.modulemap
+module Method {
+    header "method.h"
+}
+
+//--- Inputs/method.h
+
+@interface Foo
+-(void)bar:(float *)p count:(int)len __attribute__((swift_attr("@_SwiftifyImport(.countedBy(pointer: .param(1), count: \"len\"))")));
+@end
+
+//--- method.swift
+import Method
+  
+func test(foo: Foo, s: UnsafeMutableBufferPointer<Float>) {
+  foo.bar(s)
+}