[ResearchKit] Fix unit tests

- Fixes tests to reflect the new empty answer for a Choice Answer Format being ORKNullAnswerValue() instead of an empty array (introduced on the Review Step feature).
- Fixes test for task step identifier uniqueness validation (it now takes place on task init).

Author: rsanchezsaez

ResearchKitTests/ORKChoiceAnswerFormatHelperTests.m

@@ -192,11 +192,11 @@ - (void)testAnswerForSelectedIndexes {
 
         id answer = [formatHelper answerForSelectedIndexes:@[@(0)]];
 
-        XCTAssert([answer isKindOfClass:[NSArray class]] && ((NSArray *)answer).count == 0, @"%@", answer);
+        XCTAssert(answer == ORKNullAnswerValue(), @"%@", answer);
 
         answer = [formatHelper answerForSelectedIndex:0];
 
-        XCTAssert([answer isKindOfClass:[NSArray class]] && ((NSArray *)answer).count == 0, @"%@", answer);
+        XCTAssert(answer == ORKNullAnswerValue(), @"%@", answer);
 
         [textChoices enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
 

ResearchKitTests/ORKTaskTests.m

@@ -361,9 +361,8 @@ - (void)testOrderedTask {
     ORKStep *step = [[ORKInstructionStep alloc] initWithIdentifier:BlankStepIdentifier];
     [steps addObject:step];
 
-    ORKOrderedTask *orderedTask = [[ORKOrderedTask alloc] initWithIdentifier:OrderedTaskIdentifier
-                                                                       steps:steps];
-    XCTAssertThrows([orderedTask validateParameters]);
+    XCTAssertThrows([[ORKOrderedTask alloc] initWithIdentifier:OrderedTaskIdentifier
+                                                         steps:steps]);
 }
 
 #define getIndividualNavigableOrderedTaskSteps() \

ResearchKitTests/ORKTextChoiceCellGroupTests.m

@@ -272,29 +272,47 @@ - (void)testMultiChoice {
 
         [group didSelectCellAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0]];
         id answer = group.answer;
-        XCTAssert([answer isKindOfClass:[NSArray class]]);
-        NSArray *answerArray = answer;
-        XCTAssertEqual(answerArray.count, group.size - index -1);
+        if (index < group.size - 1) {
+            XCTAssert([answer isKindOfClass:[NSArray class]]);
+            NSArray *answerArray = answer;
+            XCTAssertEqual(answerArray.count, group.size - index -1);
+        } else {
+            // Answer becomes NSNull when all cells are deselected
+            XCTAssert(answer == ORKNullAnswerValue());
+        }
 
         ORKChoiceViewCell *cell = [group cellAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0] withReuseIdentifier:@"abc"];
         XCTAssertEqual( cell.selectedItem, NO);
     }
 
-    id answer = group.answer;
-    XCTAssert([answer isKindOfClass:[NSArray class]]);
-    NSArray *answerArray = answer;
-    XCTAssertEqual(answerArray.count, 0);
+    XCTAssert(group.answer == ORKNullAnswerValue());
+
+    // Select all cells again
+    for ( index = 0 ; index < group.size; index++) {
+        [group didSelectCellAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0]];
+    }
+    
+    NSArray *answerArray = group.answer;
+    XCTAssertEqual(answerArray.count, group.size);
 
     // Test set nil/null answer
     [group setAnswer:nil];
-    XCTAssertEqual(answerArray.count, 0);
+    XCTAssertNil(group.answer);
     for ( index = 0 ; index < group.size; index++) {
         ORKChoiceViewCell *cell = [group cellAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0] withReuseIdentifier:@"abc"];
         XCTAssert( cell.selectedItem == NO);
     }
-    [group setAnswer:ORKNullAnswerValue()];
-    XCTAssertEqual(answerArray.count, 0);
 
+    // Select all cells again
+    for ( index = 0 ; index < group.size; index++) {
+        [group didSelectCellAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0]];
+    }
+    
+    answerArray = group.answer;
+    XCTAssertEqual(answerArray.count, group.size);
+
+    [group setAnswer:ORKNullAnswerValue()];
+    XCTAssert(group.answer == ORKNullAnswerValue());
     for ( index = 0 ; index < group.size; index++) {
         ORKChoiceViewCell *cell = [group cellAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0] withReuseIdentifier:@"abc"];
         XCTAssertEqual(cell.selectedItem, NO);
@@ -423,9 +441,7 @@ - (void)testMultiChoiceWithExclusives:(NSArray *)choices {
         // Test cell deselection.  First deselect the exclusive, and confirm no choices are selected
         [group didSelectCellAtIndexPath:[NSIndexPath indexPathForRow:exclusiveIndex inSection:0]];
         exclusiveAnswer = group.answer;
-        XCTAssert([exclusiveAnswer isKindOfClass:[NSArray class]]);
-        exclusiveAnswerArray = exclusiveAnswer;
-        XCTAssertEqual(exclusiveAnswerArray.count, 0);
+        XCTAssert(exclusiveAnswer == ORKNullAnswerValue());
         exclusiveCell = [group cellAtIndexPath:[NSIndexPath indexPathForRow:exclusiveIndex inSection:0] withReuseIdentifier:@"abc"];
         XCTAssertEqual(exclusiveCell.selectedItem, NO);
 
@@ -495,18 +511,21 @@ - (void)testMultiChoiceWithExclusives:(NSArray *)choices {
             NSUInteger index = ((NSNumber *)nonExclusiveIndexes[nonExclusiveIndexI]).unsignedIntegerValue;
             [group didSelectCellAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0]];
             id answer = group.answer;
-            XCTAssert([answer isKindOfClass:[NSArray class]]);
-            NSArray *answerArray = answer;
-            XCTAssertEqual(answerArray.count, nonExclusiveIndexes.count - nonExclusiveIndexI - 1);
+            if (nonExclusiveIndexI < nonExclusiveIndexes.count - 1) {
+                XCTAssert([answer isKindOfClass:[NSArray class]]);
+                NSArray *answerArray = answer;
+                XCTAssertEqual(answerArray.count, nonExclusiveIndexes.count - nonExclusiveIndexI - 1);
+            } else {
+                // Answer becomes NSNull when there are no selected cells
+                XCTAssert(answer == ORKNullAnswerValue());
+            }
 
             ORKChoiceViewCell *cell = [group cellAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0] withReuseIdentifier:@"abc"];
             XCTAssertEqual( cell.selectedItem, NO);
         }
 
         id answer = group.answer;
-        XCTAssert([answer isKindOfClass:[NSArray class]]);
-        NSArray *answerArray = answer;
-        XCTAssertEqual(answerArray.count, 0);
+        XCTAssert(answer == ORKNullAnswerValue());
     }
 
     // Test set nil/null answer