From 3cef3010e6f90f03bcce8f0744dd25399b254ae0 Mon Sep 17 00:00:00 2001
From: Nick Lockwood <nicklockwood@fb.com>
Date: Fri, 7 Aug 2015 06:06:17 -0700
Subject: [PATCH] Fix RCTAssert logic

---
 React/Base/RCTAssert.h | 27 +++++++++++-----
 React/Base/RCTAssert.m | 71 +++++++++++++++++++++++++++++-------------
 2 files changed, 70 insertions(+), 28 deletions(-)

diff --git a/React/Base/RCTAssert.h b/React/Base/RCTAssert.h
index c7a331b43..05cf7bb58 100644
--- a/React/Base/RCTAssert.h
+++ b/React/Base/RCTAssert.h
@@ -14,13 +14,13 @@
 /**
  * The default error domain to be used for React errors.
  */
-extern NSString *const RCTErrorDomain;
+RCT_EXTERN NSString *const RCTErrorDomain;
 
 /**
  * A block signature to be used for custom assertion handling.
  */
 typedef void (^RCTAssertFunction)(
-  BOOL condition,
+  NSString *condition,
   NSString *fileName,
   NSNumber *lineNumber,
   NSString *function,
@@ -30,12 +30,18 @@ typedef void (^RCTAssertFunction)(
 /**
  * This is the main assert macro that you should use.
  */
-#define RCTAssert(condition, ...) do { BOOL pass = ((condition) != 0); \
-if (RCT_NSASSERT && !pass) { [[NSAssertionHandler currentHandler] handleFailureInFunction:@(__func__) \
-file:@(__FILE__) lineNumber:__LINE__ description:__VA_ARGS__]; } \
-_RCTAssertFormat(pass, __FILE__, __LINE__, __func__, __VA_ARGS__); \
+#define RCTAssert(condition, ...) do { \
+  if ((condition) == 0) { \
+    _RCTAssertFormat(#condition, __FILE__, __LINE__, __func__, __VA_ARGS__); \
+    if (RCT_NSASSERT) { \
+      [[NSAssertionHandler currentHandler] handleFailureInFunction:@(__func__) \
+        file:@(__FILE__) lineNumber:__LINE__ description:__VA_ARGS__]; \
+    } \
+  } \
 } while (false)
-RCT_EXTERN void _RCTAssertFormat(BOOL, const char *, int, const char *, NSString *, ...) NS_FORMAT_FUNCTION(5,6);
+RCT_EXTERN void _RCTAssertFormat(
+  const char *, const char *, int, const char *, NSString *, ...
+) NS_FORMAT_FUNCTION(5,6);
 
 /**
  * Convenience macro for asserting that a parameter is non-nil/non-zero.
@@ -64,6 +70,13 @@ RCT_EXTERN RCTAssertFunction RCTGetAssertFunction(void);
  */
 RCT_EXTERN void RCTAddAssertFunction(RCTAssertFunction assertFunction);
 
+/**
+ * This method temporarily overrides the assert function while performing the
+ * specified block. This is useful for testing purposes (to detect if a given
+ * function asserts something) or to suppress or override assertions temporarily.
+ */
+RCT_EXTERN void RCTPerformBlockWithAssertFunction(void (^block)(void), RCTAssertFunction assertFunction);
+
 /**
  * Get the current thread's name (or the current queue, if in debug mode)
  */
diff --git a/React/Base/RCTAssert.m b/React/Base/RCTAssert.m
index 78506f7ce..a990f7c1b 100644
--- a/React/Base/RCTAssert.m
+++ b/React/Base/RCTAssert.m
@@ -11,6 +11,8 @@
 
 NSString *const RCTErrorDomain = @"RCTErrorDomain";
 
+static NSString *const RCTAssertFunctionStack = @"RCTAssertFunctionStack";
+
 RCTAssertFunction RCTCurrentAssertFunction = nil;
 
 NSException *_RCTNotImplementedException(SEL, Class);
@@ -22,26 +24,6 @@ NSException *_RCTNotImplementedException(SEL cmd, Class cls)
                                  reason:msg userInfo:nil];
 }
 
-void _RCTAssertFormat(
-  BOOL condition,
-  const char *fileName,
-  int lineNumber,
-  const char *function,
-  NSString *format, ...)
-{
-  if (RCTCurrentAssertFunction) {
-
-    va_list args;
-    va_start(args, format);
-    NSString *message = [[NSString alloc] initWithFormat:format arguments:args];
-    va_end(args);
-
-    RCTCurrentAssertFunction(
-      condition, @(fileName), @(lineNumber), @(function), message
-    );
-  }
-}
-
 void RCTSetAssertFunction(RCTAssertFunction assertFunction)
 {
   RCTCurrentAssertFunction = assertFunction;
@@ -56,7 +38,7 @@ void RCTAddAssertFunction(RCTAssertFunction assertFunction)
 {
   RCTAssertFunction existing = RCTCurrentAssertFunction;
   if (existing) {
-    RCTCurrentAssertFunction = ^(BOOL condition,
+    RCTCurrentAssertFunction = ^(NSString *condition,
                                  NSString *fileName,
                                  NSNumber *lineNumber,
                                  NSString *function,
@@ -70,6 +52,34 @@ void RCTAddAssertFunction(RCTAssertFunction assertFunction)
   }
 }
 
+/**
+ * returns the topmost stacked assert function for the current thread, which
+ * may not be the same as the current value of RCTCurrentAssertFunction.
+ */
+static RCTAssertFunction RCTGetLocalAssertFunction()
+{
+  NSMutableDictionary *threadDictionary = [NSThread currentThread].threadDictionary;
+  NSArray *functionStack = threadDictionary[RCTAssertFunctionStack];
+  RCTAssertFunction assertFunction = [functionStack lastObject];
+  if (assertFunction) {
+    return assertFunction;
+  }
+  return RCTCurrentAssertFunction;
+}
+
+void RCTPerformBlockWithAssertFunction(void (^block)(void), RCTAssertFunction assertFunction)
+{
+  NSMutableDictionary *threadDictionary = [NSThread currentThread].threadDictionary;
+  NSMutableArray *functionStack = threadDictionary[RCTAssertFunctionStack];
+  if (!functionStack) {
+    functionStack = [[NSMutableArray alloc] init];
+    threadDictionary[RCTAssertFunctionStack] = functionStack;
+  }
+  [functionStack addObject:assertFunction];
+  block();
+  [functionStack removeLastObject];
+}
+
 NSString *RCTCurrentThreadName(void)
 {
   NSThread *thread = [NSThread currentThread];
@@ -84,3 +94,22 @@ NSString *RCTCurrentThreadName(void)
   }
   return threadName;
 }
+
+void _RCTAssertFormat(
+  const char *condition,
+  const char *fileName,
+  int lineNumber,
+  const char *function,
+  NSString *format, ...)
+{
+  RCTAssertFunction assertFunction = RCTGetLocalAssertFunction();
+  if (assertFunction) {
+
+    va_list args;
+    va_start(args, format);
+    NSString *message = [[NSString alloc] initWithFormat:format arguments:args];
+    va_end(args);
+
+    assertFunction(@(condition), @(fileName), @(lineNumber), @(function), message);
+  }
+}