CatalogPresenterTests.m

//
//  CatalogPresenterTests.m
//  PresentationUnitTestingTests
//
//  Created by Artem Stepanenko on 17/08/16.
//  Copyright © 2016 Artem Stepanenko. All rights reserved.
//

#import <XCTest/XCTest.h>
#import <OCMock/OCMock.h>
#import "TestingHelper.h"

#import "CatalogPresenter.h"
#import "CatalogViewProtocol.h"
#import "Router.h"
#import "SKRNetworking.h"
#import "SKRError.h"
#import "SKRItem.h"

@interface CatalogPresenterTests : XCTestCase

// these objects will be mocked,
// meaning any of their code won't be executed
@property (nonatomic) id<CatalogViewProtocol> mockView;
@property (nonatomic) Router *mockRouter;
@property (nonatomic) SKRNetworking *mockNetworking;

// system under test – only this object is going to be REAL
@property (nonatomic) CatalogPresenter *presenter;

@end

@implementation CatalogPresenterTests

// `setUp` is called right before each testcase method:
// we configure all involved objects from scratch
// to clear side effects from the previously executed testcases
- (void)setUp
{
    [super setUp];
    
    // mock objects
    self.mockView = OCMProtocolMock(@protocol(CatalogViewProtocol));
    self.mockRouter = OCMClassMock([Router class]);
    self.mockNetworking = OCMClassMock([SKRNetworking class]);
    
    // system under test – the catalog screen
    self.presenter = [[CatalogPresenter alloc] initWithView:self.mockView
                                                     router:self.mockRouter
                                                 networking:self.mockNetworking];
}

- (void)testThatItemsAreRequestedIfThereAreNone
{
    // we notify the screen that it's about to be shown
    [self.presenter viewWillAppear];
    
    // and verify if it fetches items
    OCMVerify([self.mockNetworking fetchAllItemsWithSuccess:[OCMArg any] failure:[OCMArg any]]);
}

- (void)testThatShowsCartWhenCartButtonTapped
{
    // we simulate a user's tap on the cart button
    [self.presenter cartTapped];
    
    // and verify if the screen shows a cart screen
    OCMVerify([self.mockRouter presentCart]);
}

- (void)testThatNoConnectionAlertAppearsIfErrorReceived
{
    // we mock the networking to make it return always 'no connection'
    // when items are requested
    OCMStub([self.mockNetworking fetchAllItemsWithSuccess:[OCMArg any] failure:[OCMArg any]]).andDo(^(NSInvocation *invocation) {
        
        void (^failureBlock)(SKRError *error);
        [invocation getArgument:&failureBlock atIndex:3];
        failureBlock([SKRError errorWithMessage:@"No internet" type:SKRErrorTypeNoInternet]);
    });
    
    // then simulate an appearance event
    [self.presenter viewWillAppear];
    
    // and verify whether the screen shows 'no connection' alert
    OCMVerify([self.mockView showNoConnection]);
}

- (void)testThatReloadsViewWhenProductsReceived
{
    // we mock the networking so it responds with a list of one item
    [self setUpNetworkingToReturnOneProduct];
    
    // then send an apearance event to the cart screen
    [self.presenter viewWillAppear];
    
    // and verify that it reloads products
    // when they are received
    OCMVerify([self.mockView reloadProducts]);
}

- (void)testThatShowsRightAmountOfProductsWhenFetched
{
    // we mock the networking to return one item
    [self setUpNetworkingToReturnOneProduct];
    
    // notify the screen about it's appearance
    [self.presenter viewWillAppear];
    
    // and verify if it really contains a single product
    NSUInteger expectedAmount = 1;
    NSUInteger actualAmount = self.presenter.products.count;
    XCTAssertEqual(expectedAmount, actualAmount, @"The amount of products must be 1");
}

- (void)testThatShowsRightProductName
{
    // so the networking gives the cart screen one item
    [self setUpNetworkingToReturnOneProduct];
    
    // the screen knows, it's going to be shown
    [self.presenter viewWillAppear];
    
    // we verify if the first products name is '911 Turbo S'
    NSString *expectedName = @"911 Turbo S";
    NSString *actualName = self.presenter.products.firstObject.name;
    XCTAssertEqualObjects(expectedName, actualName, @"The product name must be '911 Turbo S'");
}

- (void)testThatReloadsViewWhenUserSearches
{
    // the networking is mocked to return the item
    [self setUpNetworkingToReturnOneProduct];
    
    // the screen is notified and gets the item under the hood
    [self.presenter viewWillAppear];
    
    // we simulate the user searches for 'Tesla'
    [self.presenter searchQueryChanged:@"Tesla"];
    
    // and finally verify that the products are reloaded
    OCMVerify([self.mockView reloadProducts]);
}

- (void)testThatThereAreNoResultsWhenUserSearchesTesla
{
    // the networking returns the single item
    [self setUpNetworkingToReturnOneProduct];
    
    // the screen knows it's going to be shown
    [self.presenter viewWillAppear];
    
    // the user searches for 'Tesla'
    [self.presenter searchQueryChanged:@"Tesla"];
    
    // we expect the amount of search results to be zero
    // since there's only '911 Turbo S' in the list
    NSUInteger expectedAmount = 0;
    NSUInteger actualAmount = self.presenter.products.count;
    XCTAssertEqual(expectedAmount, actualAmount, @"The amount of Tesla-s must be zero");
}

- (void)testThatThereIsOneProductWhenUserSearches911
{
    // ...the item
    [self setUpNetworkingToReturnOneProduct];
    
    // ...the notification
    [self.presenter viewWillAppear];
    
    // the user's search query is '911'
    [self.presenter searchQueryChanged:@"911"];
    
    // so the search results must contain '911 Turbo S'
    NSUInteger expectedAmount = 1;
    NSUInteger actualAmount = self.presenter.products.count;
    XCTAssertEqual(expectedAmount, actualAmount, @"There must be '911 Turbo S' in the search results");
}

#pragma mark - Private

- (void)setUpNetworkingToReturnOneProduct
{
    NSDictionary *productDictionary = [TestingHelper someProductDictionary];
    
    OCMStub([self.mockNetworking fetchAllItemsWithSuccess:[OCMArg any] failure:[OCMArg any]]).andDo(^(NSInvocation *invocation) {
        
        void (^successBlock)(NSArray *responseObject);
        [invocation getArgument:&successBlock atIndex:2];
        successBlock(@[productDictionary]);
    });
}

@end