api.md

This package contains an implementation of SparkyTestHelpers.Scenarios for "MsTest" / VisualStudio.TestTools.

The only differences are:

• If you use MsTest's Assert.Inconclusive() in a scenario test, your scenario "suite" will be recognized as inconclusive and not as a failure by the Visual Studio test runner.
• The "using" statement is using SparkyTestHelpers.Scenarios.MsTest.MsTest; instead of using SparkyTestHelpers.Scenarios.MsTest;

---

see also:

• the rest of the "Sparky suite" of .NET utilities and test helpers

---

MsTestScenarioTester<TScenario>

VisualStudio.TestTools now has "DataMemberTest" and "DataRow" attributes, but they didn't when I started using the framework, so I wrote my own "scenerio testing" tool based my experience with NUnit "TestCase" attributes. This class provides the ability to execute the same test code for multiple test cases and, after all test cases have been executed, fail the unit test if any of the test cases failed.

Even if your test framework has attribute-based scenario testing, these helpers provide an alternative syntax that you might find useful.

This class is rarely used directly. It's easier to use with IEnumerable<TScenario>.TestEach or ForTest.Scenarios (see below).

When one or more of the scenarios fails, the failure exception shows which were unsuccessful, for example, this scenario test:

ForTest.Scenarios
(
    new { DateString = "1/31/2023", IsGoodDate = true },
    new { DateString = "2/31/2023", IsGoodDate = true },
    new { DateString = "6/31/2023", IsGoodDate = false }
)
.TestEach(scenario =>
{
    DateTime dt;
    Assert.AreEqual(scenario.IsGoodDate, DateTime.TryParse(scenario.DateString, out dt));
});

...throws this exception:

Test method SparkyTestHelpers.UnitTests.DateTests threw exception:
SparkyTestHelpers.Scenarios.ScenarioTestFailureException: Scenario[1] (2 of 3) - Assert.AreEqual failed. Expected:<True>. Actual:<False>.

Scenario data - anonymousType: {"DateString":"2/31/2023","IsGoodDate":true}

Scenario[2] (3 of 3) - Assert.AreEqual failed. Expected:<True>. Actual:<False>.

Scenario data - anonymousType: {"DateString":"4/31/2023","IsGoodDate":true}

Public Methods

• ScenarioTester BeforeEachTest(Action<TScenario>)

  Defines action to called before each scenario is tested.

Example

ForTest.Scenarios(*array*)
.BeforeEachTest(scenario => 
{
    // do something, e.g. reset mocks, log scenario details
});
.TestEach(scenario =>
{
    DateTime dt;
    Assert.AreEqual(scenario.IsGoodDate, DateTime.TryParse(scenario.DateString, out dt));
});

• ScenarioTester AfterEachTest(Action<TScenario>)

  Defines function called after each scenario is tested. The function receives the scenario and the exception (if any) caught by the test. If the function returns true, the scenario test is "passed". If false, exception is thrown to fail the test.

Example

ForTest.Scenarios(*array*)
.AfterEachTest((scenario, ex) => 
{
    // do something, e.g. log scenario details, 
    // decide if scenario with exception should be passed
    return ex == null;
});
.TestEach(scenario =>
{
    DateTime dt;
    Assert.AreEqual(scenario.IsGoodDate, DateTime.TryParse(scenario.DateString, out dt));
});

---

ScenarioTesterExtension

ScenarioTester<TScenario> extension methods.

Static Methods

• ScenarioTester<TScenario> TestEach(IEnumerable<TScenario> enumerable, Action<TScenario> test)

Example

using SparkyTestHelpers.Scenarios.MsTest;
. . .
new []
{
    new { DateString = "1/31/2023", IsGoodDate = true },  
    new { DateString = "2/31/2023", IsGoodDate = false } 
}
.TestEach(scenario =>
{
    DateTime dt;
    Assert.AreEqual(scenario.IsGoodDate, DateTime.TryParse(scenario.DateString, out dt));  
});  

---

ForTest

"Syntactic sugar" methods for working with ScenarioTester<TScenario>

Static Methods

• ForTest.Scenarios(TScenario[] scenarios) - creates array of scenarios that can be "dotted" to the TestEach extension method:

Example

using SparkyTestHelpers.Scenarios.MsTest;
. . .
ForTest.Scenarios
(
    new { DateString = "1/31/2023", IsGoodDate = true },  
    new { DateString = "2/31/2023", IsGoodDate = false }
)
.TestEach(scenario =>
{
    DateTime dt;
    Assert.AreEqual(scenario.IsGoodDate, DateTime.TryParse(scenario.DateString, out dt));  
});  

• IEnumerable<TEnum> EnumValues() - tests each value in an enum.

Example

using SparkyTestHelpers.Scenarios.MsTest;
. . .
ForTest.EnumValues<OrderStatus>()
    .TestEach(orderStatus => foo.Bar(orderStatus));

• IEnumerable<TEnum> ExceptFor(IEnumerable<TEnum> values, TEnum[] valuesToExclude) - Exclude enum values from test scenarios.

Example

using SparkyTestHelpers.Scenarios.MsTest;
. . .
ForTest.EnumValues<OrderStatus>()
    .ExceptFor(OrderStatus.Cancelled)
    .TestEach(orderStatus => foo.Bar(orderStatus));