public async Task User1_transfer_to_both_users_at_same_time_method_1()
{
var contextCreator = new TestingDbContextCreator("User1_transfer_to_both_users_at_same_time_method_1");
var context = contextCreator.CreateSimpleBankDbContextForTesting();
// Arrange the data for the test
decimal user1Balance = 10000; decimal user2Balance = 100; decimal user3Balance = 1000;
await this.CreateUserTask("user1", "12345", user1Balance, context);
await this.CreateUserTask("user2", "12345", user2Balance, context);
await this.CreateUserTask("user3", "12345", user3Balance, context);
var context1 = contextCreator.GetFreshDbContext();
var context2 = contextCreator.GetFreshDbContext();
var user1InContext1 = context1.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "user1");
var user2InContext1 = context1.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "user2");
var user1InContext2 = context2.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "user1");
var user3InContext2 = context2.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "user3");
// Act
// initialize the transfer in 2 different dbContext
var transferInContext1 = new UserService(context1).Transfer(
user1InContext1.ID, user2InContext1.ID,
900,
user1InContext1.Timestamp, user2InContext1.Timestamp);
var transferInContext2 = new UserService(context2).Transfer(
user1InContext2.ID, user3InContext2.ID,
1000,
user1InContext2.Timestamp, user3InContext2.Timestamp);
// exec 2 transfer in parallel
var allTasks = await Task.WhenAll(transferInContext1, transferInContext2);
// Assert
// assert there is existing ErrorList in allTasks
Assert.True(allTasks.Any(x => x.ErrorList.Count > 0));
// create new dbContext to query latest data in database
using (var assertContext = contextCreator.GetFreshDbContext())
{
var updatedUser1 = assertContext.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "user1");
var updatedUser2 = assertContext.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "user2");
var updatedUser3 = assertContext.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "user3");
// assert the balance of user1 is 9100 (if transfer1 is success) OR 9000 (if transfer2 is success)
Assert.True(updatedUser1.Balance == 9100 || updatedUser1.Balance == 9000);
// assert the balance of user2 is 1000 AND balance of user3 is 1000 if the transferInContext1 is success
// OR assert the balance of user2 is 100 AND balance of user3 is 2000 if the transferInContext2 is success
Assert.True((updatedUser2.Balance == 1000 && updatedUser3.Balance == 1000) ||
(updatedUser2.Balance == 100 && updatedUser3.Balance == 2000));
}
}
public async Task User1_transfer_to_both_users_at_same_time_method_2()
{
var contextCreator = new TestingDbContextCreator("User1_transfer_to_both_users_at_same_time_method_2");
var context = contextCreator.CreateSimpleBankDbContextForTesting();
// Arrange the data for the test
decimal userABalance = 10000; decimal userBBalance = 100; decimal userCBalance = 1000;
await this.CreateUserTask("userA", "6789", userABalance, context);
await this.CreateUserTask("userB", "6789", userBBalance, context);
await this.CreateUserTask("userC", "6789", userCBalance, context);
var context1 = contextCreator.GetFreshDbContext();
var context2 = contextCreator.GetFreshDbContext();
// create context1 data
var userAInContext1 = context1.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "userA");
var userBInContext1 = context1.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "userB");
// create context2 data
var userAInContext2 = context2.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "userA");
var userCInContext2 = context2.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "userC");
// Act
// exec 2 transfer in parallel
ConcurrentDictionary <string, Task <BankUserUpdateModel> > resultInParallel = new ConcurrentDictionary <string, Task <BankUserUpdateModel> >();
Parallel.Invoke(
() =>
{
var transfer = new UserService(context1).Transfer(
userAInContext1.ID, userBInContext1.ID,
900,
userAInContext1.Timestamp, userBInContext1.Timestamp);
resultInParallel.TryAdd("transferInContext1", transfer);
},
() =>
{
var transfer = new UserService(context2).Transfer(
userAInContext2.ID, userCInContext2.ID,
1000,
userAInContext2.Timestamp, userCInContext2.Timestamp);
resultInParallel.TryAdd("transferInContext2", transfer);
});
// Assert
// assert there is existing ErrorList in resultInParallel
Assert.True(resultInParallel.Any(x => x.Value.Result.ErrorList.Count > 0));
// create new dbContext to query latest data in database
using (var assertContext = contextCreator.GetFreshDbContext())
{
var updatedUserA = assertContext.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "userA");
var updatedUserB = assertContext.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "userB");
var updatedUserC = assertContext.BankUsers.AsNoTracking().SingleOrDefault(x => x.AccountNumber == "userC");
// assert the balance of userA is 9100 (if transfer1 is success) OR 9000 (if transfer2 is success)
Assert.True(updatedUserA.Balance == 9100 || updatedUserA.Balance == 9000);
// assert the balance of userB is 1000 AND balance of userC is 1000 if the transferInContext1 is success
// OR assert the balance of userB is 100 AND balance of userC is 2000 if the transferInContext2 is success
Assert.True((updatedUserB.Balance == 1000 && updatedUserC.Balance == 1000) ||
(updatedUserB.Balance == 100 && updatedUserC.Balance == 2000));
}
}