Fixtures
An example showing usage of test fixtures in the OTest2 framework.
Full source code of the example
In the world of unit-tests a fixture is an object which can be initialized before a test and destroyed after the test. A fixture can prepare a testing environment (injection of mocked dependencies), fill data into a database, generate files working as input of the test and many other.
The OTest2 framework supports fixtures widely - test suites and test cases are fixtures themselves. And any member of testing objects can be a fixture too - see next example for more details.
The OTest2 framework initializes fixture objects (test suites and cases and user defined fixtures) in two phases:
- the fixture variable is created by their constructor methods,
- the start-up method of the fixture object is invoked.
Complementarily, destruction of the fixture object is executed in two symmetric phases:
- the tear-down method of the testing object is invoked,
- the fixture variable is destroyed by its destructor methods.
The first phase is the natural C++ way - the fixtures are just C++ variables. The framework creates suites and cases just prior their run and destroys them instantly when they finish. Hence, lifetime of any fixture is strictly limited to the lifetime of its particular test. No fixture is created during dynamic initialization of the test binary.
The start-up and tear-down methods are just member functions of a fixture object invoked at the beginning and at the end. The framework promises that the tear-down method is called every time even if the test object fails or ends up with an unhandled exception.
OK, let’s get an example:
#include <otest2/otest2.h>
#include <iostream>
#include <memory>
#include "myfixture.h"
namespace OTest2 {
namespace Examples {
namespace Test {
TEST_SUITE(Fixtures) {
/* -- This fixture's variable is initialized in the constructor method
* of the suite. The round braces are mandatory - OTest2 doesn't support
* other syntax of initializers. */
MyFixture fixture1("Number one");
/* -- This is a suite's variable initialized in the start-up method. */
std::unique_ptr<MyFixture> fixture2;
TEST_START_UP() {
/* -- This method is invoked at the beginning of the suite. The second
* variable is created here. */
fixture2.reset(new MyFixture("Number two"));
}
TEST_TEAR_DOWN() {
/* -- This method is invoked at the end of the suite. The second variable
* is explicitly destroyed here. */
fixture2.reset(nullptr);
}
TEST_CASE(FirstCase) {
/* -- Variables of the first case. */
MyFixture fixture3("Number three");
std::unique_ptr<MyFixture> fixture4;
TEST_START_UP() {
fixture4.reset(new MyFixture("Number four"));
}
TEST_TEAR_DOWN() {
fixture4.reset(nullptr);
}
TEST_SIMPLE() {
std::cout << "enter case 1" << std::endl;
testAssert(fixture1.checkName("Number one"));
testAssert(fixture2->checkName("Number two"));
testAssert(fixture3.checkName("Number three"));
testAssert(fixture4->checkName("Number four"));
std::cout << "leave case 1" << std::endl;
throw "An exception - the fixtures are cleaned up anyway";
}
}
TEST_CASE(SecondCase) {
/* -- This variable shadows the suite's variable. In the entire test case
* this variable is used instead of the suite's one. */
MyFixture fixture1("Number five");
TEST_SIMPLE() {
std::cout << "enter case 2" << std::endl;
testAssert(fixture1.checkName("Number five"));
testAssert(fixture2->checkName("Number two"));
std::cout << "leave case 2" << std::endl;
}
}
}
} /* -- namespace Test */
} /* -- namespace Examples */
} /* -- namespace OTest2 */If you compile and run this test you’ll got similar output (without added line numbers):
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
================================== Fixtures ==================================
started 'Number one'
started 'Number two'
started 'Number three'
started 'Number four'
enter case 1
leave case 1
error in fixtures::Fixtures::FirstCase: unexpected unknown exception
stopped 'Number four'
stopped 'Number three'
FirstCase [Failed]
started 'Number five'
enter case 2
leave case 2
stopped 'Number five'
SecondCase [Passed]
stopped 'Number two'
stopped 'Number one'
------------------------------------------------------------------------------
Suite total [Failed]
================================ Test results ================================
Passed Failed Total
Suites 0 1 1
Cases 1 1 2
Checks 6 0 6
Errors 1
Test total [Failed]
==============================================================================
- line 02: the test suite object is created and fixture1 is initialized in its constructor.
- line 03: the start-up method of the suite object is invoked and fixture2 is initialized in.
- line 04: the test case object is created and fixture3 is initialized in its constructor.
- line 05: the start-up method of the test case object is invoked and fixture4 is created in.
- line 06: the test case body is run.
- line 08: the test case ends up by an exception. The framework catches it and reports failure.
- line 09: the tear-down method of the test case object is invoked. fixture4 is destroyed in.
- line 10: the test case object is destroyed. During its destruction fixture3 is destroyed too.
- line 11: the result of the destroyed test case object is reported.
- line 12: the second test case is created and the shadowing fixture1 too.
- line 15: the tear-down method of the second test case is invoked and the shadowing fixture1 is destroyed.
- line 16: the result of the second test case is reported.
- line 17: the tear-down method of the suite is invoked and the fixture2 is destroyed in.
- line 18: the suite object is destroyed. During its destruction fixture1 is destroyed too.
- line 19: the result of the suite object is reported.