Add strong enforcement that the currentState never transitions to `…

…nil`
blakewatters · Jun 24, 2015 · 46dcde7 · 46dcde7
1 parent a85b966
commit 46dcde7
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Showing 2 changed files with 25 additions and 2 deletions.
diff --git a/Code/TKStateMachine.m b/Code/TKStateMachine.m
@@ -104,6 +104,14 @@ - (void)setInitialState:(TKState *)initialState
     _initialState = initialState;
 }
 
+- (void)setCurrentState:(TKState *)currentState
+{
+    if (currentState == nil) {
+        [NSException raise:NSInvalidArgumentException format:@"Cannot assign currentState to `nil`: Expected a `TKState` object. (%@)", self];
+    }
+    _currentState = currentState;
+}
+
 - (NSSet *)states
 {
     return [NSSet setWithSet:self.mutableStates];
@@ -288,7 +296,6 @@ - (id)copyWithZone:(NSZone *)zone
 {
     TKStateMachine *copiedStateMachine = [[[self class] allocWithZone:zone] init];
     copiedStateMachine.active = NO;
-    copiedStateMachine.currentState = nil;
     copiedStateMachine.initialState = self.initialState;
 
     for (TKState *state in self.states) {

diff --git a/Specs/TKStateMachineSpec.m b/Specs/TKStateMachineSpec.m
@@ -57,6 +57,10 @@ - (void)startTryingToPickUpCollegeGirls {}
         [stateMachine.initialState shouldBeNil];
     });
 
+    it(@"has a nil current state", ^{
+        [stateMachine.currentState shouldBeNil];
+    });
+
     it(@"has no events", ^{
         [[stateMachine.events should] haveCountOf:0];
     });
@@ -263,11 +267,23 @@ - (void)startTryingToPickUpCollegeGirls {}
         stateMachine.initialState = [stateMachine stateNamed:@"Dating"];
         [stateMachine activate];
     });
+
+    context(@"when attempting to set the currentState to `nil`", ^{
+        it(@"should raise", ^{
+            __block NSException *exception;
+            @try {
+                [stateMachine setValue:nil forKey:@"currentState"];
+            } @catch (NSException *anException) {
+                exception = anException;
+            }
+            [[exception.name should] equal:NSInvalidArgumentException];
+            [[exception.reason should] startWithString:@"Cannot assign currentState to `nil`: Expected a `TKState` object."];
+        });
+    });
 
     it(@"invokes callbacks with a TKTransition describing the state change", ^{
         __block TKTransition *blockTransition;
         [singleState setWillEnterStateBlock:^(TKState *state, TKTransition *transition) {
-            NSLog(@"dsfdsfds");
             blockTransition = transition;
         }];
         NSError *error = nil;