NSKVOSupport: Add observer via proxy test

The new KVO implementation for libobjc2/clang, located in Source/NSKVO*, reuses
or installs a hidden class and subsequently adds the swizzled method to the
hidden class. Make sure that the invocation mechanism calls the swizzled method.

Tests/base/NSKVOSupport/proxy.m

@@ -0,0 +1,160 @@
+#import <GNUstepBase/GNUstep.h>
+
+#import <Foundation/NSProxy.h>
+#import <Foundation/NSInvocation.h>
+#import <Foundation/NSObject.h>
+#import <Foundation/NSString.h>
+#import <Foundation/NSDictionary.h>
+#import <Foundation/NSSet.h>
+#import <Foundation/NSAutoreleasePool.h>
+#import <Foundation/NSKeyValueObserving.h>
+
+#import "Testing.h"
+
+
+@interface Observee : NSObject
+{
+    NSString *_name;
+    NSString *_derivedName;
+}
+
+- (NSString *) name;
+- (void) setName: (NSString *)name;
+
+- (NSString *) derivedName;
+- (void) setDerivedName: (NSString *)name;
+
+@end
+
+@implementation Observee
+
+- (NSString *) name
+{
+    return [[_name retain] autorelease];
+}
+- (void) setName: (NSString *)name
+{
+    ASSIGN(_name, name);
+}
+
+- (NSString *)derivedName
+{
+	return [NSString stringWithFormat:@"Derived %@", self.name];
+}
+- (void) setDerivedName: (NSString *)name
+{
+    ASSIGN(_derivedName, name);
+}
+
++ (NSSet *)keyPathsForValuesAffectingDerivedName
+{
+	return [NSSet setWithObject:@"name"];
+}
+
+- (void) dealloc {
+    RELEASE(_name);
+    RELEASE(_derivedName);
+    [super dealloc];
+}
+
+@end
+
+@interface TProxy : NSProxy
+{
+    id _proxiedObject;
+}
+@end
+
+@implementation TProxy
+
+- (instancetype)initWithProxiedObject:(id)proxiedObject
+{
+    ASSIGN(_proxiedObject, proxiedObject);
+	return self;
+}
+
+- (void)forwardInvocation:(NSInvocation *)invocation
+{
+	[invocation invokeWithTarget:_proxiedObject];
+}
+
+- (NSMethodSignature *)methodSignatureForSelector:(SEL)sel
+{
+	return [_proxiedObject methodSignatureForSelector:sel];
+}
+
+- (void) dealloc
+{
+    RELEASE(_proxiedObject);
+    [super dealloc];
+}
+
+@end
+
+@interface Observer: NSObject
+
+- (void)runTest;
+
+@end
+
+@implementation Observer
+{
+    int count;
+}
+
+- (void)runTest
+{
+	Observee *obj = [[Observee alloc] init];
+	TProxy *proxy = [[TProxy alloc] initWithProxiedObject:obj];
+	
+	[(Observee *)proxy addObserver:self forKeyPath:@"name" options:NSKeyValueObservingOptionNew context:NULL];
+	[(Observee *)proxy addObserver:self forKeyPath:@"derivedName" options:NSKeyValueObservingOptionNew context:NULL];
+	
+	[((Observee *)proxy) setName: @"MOO"];
+    PASS(count == 2, "Got two change notifications");
+	
+	[obj setName: @"BAH"];
+    PASS(count == 4, "Got two change notifications");
+	
+	[(Observee *)proxy removeObserver:self forKeyPath:@"name" context:NULL];
+	[(Observee *)proxy removeObserver:self forKeyPath:@"derivedName" context:NULL];
+
+    [proxy release];
+    [obj release];
+}
+
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
+{
+    count += 1;
+    switch (count) {
+        case 1:
+            PASS_EQUAL(keyPath, @"derivedName", "change notification for dependent key 'derivedName' is emitted first");
+            break;
+        case 2:
+            PASS_EQUAL(keyPath, @"name", "'name' change notification for proxy is second");
+            break;
+        case 3:
+            PASS_EQUAL(keyPath, @"derivedName", "'derivedName' change notification for object is third");
+            break;
+        case 4:
+            PASS_EQUAL(keyPath, @"name", "'name' change notification for object is fourth");
+            break;
+        default:
+            PASS(0, "unexpected -[Observer observeValueForKeyPath:ofObject:change:context:] callback");
+    }
+}
+
+@end
+
+int
+main(int argc, char *argv[])
+{
+    NSAutoreleasePool *arp = [NSAutoreleasePool new];
+    Observer *obs = [Observer new];
+
+    [obs runTest];
+    [obs release];
+
+    DESTROY(arp);
+    return 0;
+}