I am using RSpec.shared_context to set variables that all the describe blocks will use.
Something like this
RSpec.shared_context "common" do
let(:name) { #creates a database object }
#more let statements
end
Now I invoke it from describe block like so
describe "common test" do
include_context "common"
#run few tests
end
Now after running the describe block I want to clean it up. How do I rollback all the objects created in the shared context?
I tried cleaning it in the after(:context) hook but since it is a let statement the variable name is only allowed inside examples.
Is there someway I can use use_transactional_fixtures to clean this up after running the tests in the describe block.
You don't need to worry about cleaning up your "lets" if you just setup your test suite properly to wipe the database.
Use let to define a memoized helper method. The value will be cached
across multiple calls in the same example but not across examples.
Note that let is lazy-evaluated: it is not evaluated until the first
time the method it defines is invoked.
In almost every case you want teardown to happen automatically and per example. Thats what config.transactional_fixtures does - it rolls back the database after every example so that you have a fresh slate and don't get test ordering issues. Relying on each example / context whatever to explicitly clean up after itself is just a recipe for failure.
Related
pytest allows the creation of fixtures that are automatically applied to every test in a test suite (via the autouse keyword argument). This is useful for implementing setup and teardown actions that affect every test case. More details can be found in the pytest documentation.
In theory, the same infrastructure would also be very useful for verifying post-conditions that are expected to exist after each test runs. For example, maybe a log file is created every time a test runs, and I want to make sure it exists when the test ends.
Don't get hung up on the details, but I hope you get the basic idea. The point is that it would be tedious and repetitive to add this code to each test function, especially when autouse fixtures already provide infrastructure for applying this action to every test. Furthermore, fixtures can be packaged into plugins, so my check could be used by other packages.
The problem is that it doesn't seem to be possible to cause a test failure from a fixture. Consider the following example:
#pytest.fixture(autouse=True)
def check_log_file():
# Yielding here runs the test itself
yield
# Now check whether the log file exists (as expected)
if not log_file_exists():
pytest.fail("Log file could not be found")
In the case where the log file does not exist, I don't get a test failure. Instead, I get a pytest error. If there are 10 tests in my test suite, and all of them pass, but 5 of them are missing a log file, I will get 10 passes and 5 errors. My goal is to get 5 passes and 5 failures.
So the first question is: is this possible? Am I just missing something? This answer suggests to me that it is probably not possible. If that's the case, the second question is: is there another way? If the answer to that question is also "no": why not? Is it a fundamental limitation of pytest infrastructure? If not, then are there any plans to support this kind of functionality?
In pytest, a yield-ing fixture has the first half of its definition executed during setup and the latter half executed during teardown. Further, setup and teardown aren't considered part of any individual test and thus don't contribute to its failure. This is why you see your exception reported as an additional error rather than a test failure.
On a philosophical note, as (cleverly) convenient as your attempted approach might be, I would argue that it violates the spirit of test setup and teardown and thus even if you could do it, you shouldn't. The setup and teardown stages exist to support the execution of the test—not to supplement its assertions of system behavior. If the behavior is important enough to assert, the assertions are important enough to reside in the body of one or more dedicated tests.
If you're simply trying to minimize the duplication of code, I'd recommend encapsulating the assertions in a helper method, e.g., assert_log_file_cleaned_up(), which can be called from the body of the appropriate tests. This will allow the test bodies to retain their descriptive power as specifications of system behavior.
AFAIK it isn't possible to tell pytest to treat errors in particular fixture as test failures.
I also have a case where I would like to use fixture to minimize test code duplication but in your case pytest-dependency may be a way to go.
Moreover, test dependencies aren't bad for non-unit tests and be careful with autouse because it makes tests harder to read and debug. Explicit fixtures in test function header give you at least some directions to find executed code.
I prefer using context managers for this purpose:
from contextlib import contextmanager
#contextmanager
def directory_that_must_be_clean_after_use():
directory = set()
yield directory
assert not directory
def test_foo():
with directory_that_must_be_clean_after_use() as directory:
directory.add("file")
If you absoulutely can't afford to add this one line for every test, it's easy enough to write this as a plugin.
Put this in your conftest.py:
import pytest
directory = set()
# register the marker so that pytest doesn't warn you about unknown markers
def pytest_configure(config):
config.addinivalue_line("markers",
"directory_must_be_clean_after_test: the name says it all")
# this is going to be run on every test
#pytest.hookimpl(hookwrapper=True)
def pytest_runtest_call(item):
directory.clear()
yield
if item.get_closest_marker("directory_must_be_clean_after_test"):
assert not directory
And add the according marker to your tests:
# test.py
import pytest
from conftest import directory
def test_foo():
directory.add("foo file")
#pytest.mark.directory_must_be_clean_after_test
def test_bar():
directory.add("bar file")
Running this will give you:
fail.py::test_foo PASSED
fail.py::test_bar FAILED
...
> assert not directory
E AssertionError: assert not {'bar file'}
conftest.py:13: AssertionError
You don't have to use markers, of course, but these allow controlling the scope of the plugin. You can have the markers per-class or per-module as well.
I have a large suite of tests that are currently running in series. I would like to make the suite parallelizable as much as possible. One big problem I have is that some tests require certain global application state to be set one way, and some require it to be set another way. Is there a way I can make the NUnit test runner group my tests based on which global state they require, and then run the tests within each group in parallel with each other, and modify the global state between groups?
For example, let's say there is a global setting Foo and a custom attribute [RequiresFoo(X)] that can be used to annotate which Foo value a test requires. At runtime I want NUnit to group all tests by their argument to RequiresFoo, counting unmarked tests as having some default Foo value.
Then for each group, I want it to
Set Foo = N where N is the Foo value for that group.
Run all tests in that group in parallel.
In an ideal world I would have a mock system for this global state, but that would take a lot of time that I don't have right now. Can I get NUnit to do this or something like it?
Note, I need to be able to execute any method between groups, not just set a variable. The global context I'm actually dealing with can involve starting or stopping microservices, updating configuration files, etc. I can serialize any of these requirements to a string to pass to a custom attribute, but at runtime I need to be able to run arbitrary code to parse the requirements and reconfigure the environment.
Here is a pseudo-code example.
By default tests execute in series like this:
foreach (var t in allTests)
{
Run(t);
}
NUnits basic parallel behavior is like this:
Parallel.ForEach(allTests, t => Run(t));
I want something like this:
var grouped = allTests
.GroupBy(t => GetRequirementsFromCustomAttributes(t));
foreach (var g in grouped)
{
SetGlobalState(g.Key);
Parallel.ForEach(g, t => Run(t));
}
As you state the problem, it's not yet possible in NUnit. There is a feature planned but not yet implemented that would allow arbitrary grouping of tests that may not run together.
Your workaround is to make each "group" a test, since NUnit only allows specification of parallelization on tests. Note that by test, we mean either a test case or a group of tests, i.e. fixture or namespace suite.
Putting [Parallelizable] on a test anywhere in the hierarchy causes that test to run in parallel with other tests at the same level. Putting [NonParallelizable] on it causes that same test to run in isolation.
Let's say you have five fixtures that require a value of Foo. You would make each of those fixtures non-parallelizable. In that way, none of them could run at the same time and interfere with the others.
If you want to allow those fixtures to run in parallel with other non-Foo fixtures, simply put them all in the same namespace, like Tests.FooRequred.
Create a SetupFixture in that namespace - possibly a dummy without any actual setup action. Put the [Parallelizable] attribute on it.
The group of all foo tests would then run in parallel with other tests while the individual fixtures would not run in parallel with one another.
I'm applying TDD to my first event centric project (CQRS, Event sourcing etc) and I'm writing my tests according to Greg Young's simple testing framework Given, When, Expect. My test fixture takes a command, commandhandler and aggregate root and then tests the events outputted.
CommandTestFixture<TCommand, TCommandHandler, TAggregateRoot>
For example here is a typical test
[TestFixture]
public class When_moving_a_group :
CommandTestFixture<MoveGroup, MoveGroupHandler, Foo>
I am very happy with these tests on the whole but with the the above test I've hit a problem. The aggregate root contains a collection of groups. The command MoveGroup reorders the collection, taking a from & to index. I setup the test and asserted that the correct GroupMoved event was generated with the correct data.
As an additional test I need to assert that the reordering of the Groups collection actually took place correctly? How do I do this when the aggregate root has no public getters/setters. I could add a method to retrieve the group at a particular index but isn't this breaking encapsulation simply to be testable?
What's the correct way to go about this?
EDIT
The reordering of the groups takes place in the GroupMoved handler on the Aggregate root.
private void Apply(GroupMoved e)
{
var moved = groups[e.From];
groups.RemoveAt(e.From);
groups.Insert(e.To, moved);
}
The friction here comes because you want to assert something about the internal implementation, but what you have at hand is at the top level.
Your tests and assertions need to be at the same logical level. There are two ways to re-arrange this:
What effect does re-ordering groups have on subsequent commands or queries which you do have at the top level?
This should give you an avenue for asserting that the correct outcome occurs without needing to assert anything about the ordering of the groups directly. This keeps the test at the top level and would allow all sorts of internal refactoring (e.g. perhaps lazy sorting of the groups).
Can you test at a lower level?
If you feel that testing as described above is too complicated, you might want to frame your test at a more detailed level. I think of this like focusing in on a section of detail to get it right.
Down at this level (rather than your composite root), the interfaces will know about groups and you'll have the opportunity to assert what you want to assert.
Alternatively, do you need this test at all?
If you can not find a suitable test at either of the above levels, then are you sure you need this test at all? If there is no visible external difference then there is no need to lock the behaviour in place with a test.
I am testing EJB 3.1. I have a situation where I need to start a transaction manually in my test, perform some CRUD operations within it (to create some test data which is still not committed) and then call a method in my bean to which the transaction from my test will be propagated.
By default, while using Unitils DatabaseModule, the transactions are automatically created in the test. I understand that it is possible to change this default configuration by modifying unitils.properties as follows,
DatabaseModule.Transactional.value.default=disabled
My question is: Is there a possibility to change this configuration dynamically in the test method? I do not want the transactions to be disabled "always". By default transactions can be "commit", and when required, I want to dynamically set it to "disabled".
-Thanks.
You could try this: https://stackoverflow.com/a/6561782/411229
Not sure if it will work for transaction configuration, but worth a shot.
I am writing unit tests for a PHP class that maintains users in a database. I now want to test if creating a user works, but also if deleting a user works. I see multiple possibilities to do that:
I only write one method that creates a user and deletes it afterwards
I write two methods. The first one creates the user, saves it's ID. The second one deletes that user with the saved ID.
I write two methods. The first one only creates a user. The second method creates a user so that there is one that can afterwards be deleted.
I have read that every test method should be independent of the others, which means the third possibility is the way to go, but that also means every method has to set up its test data by itself (e.g. if you want to test if it's possible to add a user twice).
How would you do it? What is good unit testing style in this case?
Two different things = Two tests.
Test_DeleteUser() could be in a different test fixture as well because it has a different Setup() code of ensuring that a User already exists.
[SetUp]
public void SetUp()
{
CreateUser("Me");
Assert.IsTrue( User.Exists("Me"), "Setup failed!" );
}
[Test]
public void Test_DeleteUser()
{
DeleteUser("Me");
Assert.IsFalse( User.Exists("Me") );
}
This means that if Test_CreateUser() passes and Test_DeleteUser() doesn't - you know that there is a bug in the section of the code that is responsible for deleting users.
Update: Was just giving some thought to Charlie's comments on the dependency issue - by which i mean if Creation is broken, both tests fail even though Delete. The best I could do was to move a guard check so that Setup shows up in the Errors and Failures tab; to distinguish setup failures (In general cases, setup failures should be easy to spot by an entire test-fixture showing Red.)
How you do this codependent on how you utilize Mocks and stubs. I would go for the more granular approach so having 2 different tests.
Test A
CreateUser("testuser");
assertTrue(CheckUserInDatabase("testuser"))
Test B
LoadUserIntoDB("testuser2")
DeleteUser("testuser2")
assertFalse(CheckUserInDatabase("testuser2"))
TearDown
RemoveFromDB("testuser")
RemoveFromDB("testuser2")
CheckUserInDatabase(string user)
...//Access DAL and check item in DB
If you utilize mocks and stubs you don't need to access the DAL until you do your integration testing so won't need as much work done on the asserting and setting up the data
Usually, you should have two methods but reality still wins over text on paper in the following case:
You need a lot of expensive setup code to create the object to test. This is a code smell and should be fixed but sometimes, you really have no choice (think of some code that aggregates data from several places: You really need all those places). In this case, I write mega tests (where a test case can have thousands of lines of code spread over many methods). It creates the database, all tables, fills them with defined data, runs the code step by step, verifies each step.
This should be a rare case. If you need one, you must actively ignore the rule "Tests should be fast". This scenario is so complex that you want to check as many things as possible. I had a case where I would dump the contents of 7 database tables to files and compare them for each of the 15 SQL updates (which gave me 105 files to compare in a single test) plus about a million asserts that would run.
The goal here is to make the test fail in such a way that you notice the source of the problem right away. It's like pouring all the constraints into code and make them fail early so you know which line of app code to check. The main drawback is that these test cases are hell to maintain. Every change of the app code means that you'll have to update many of the 105 "expected data" files.