Controlling Mock Dependencies in JustMock for Specific Assertion Behavior
Environment
| Product | Version |
|---|---|
| Progress® Telerik® JustMock | 2021.2.511.1 |
Description
While using Progress® Telerik® JustMock, you might encounter an unexpected behavior where an assertion on a mock object incorrectly includes assertions for another mock object that is used as a return value in one of its arrangements. This can lead to confusion when assertions fail for the wrong reasons.
This knowledge base article also answers the following questions:
- How can I isolate mock assertions in JustMock?
- What is the correct way to set up mock dependencies in JustMock?
- How do I ensure accurate assertion behavior for mock objects in JustMock?
Solution
The behavior observed is due to JustMock's feature that automatically creates dependencies between mocks when one mock is returned as a result of another mock's arrangement. This can inadvertently cause assertions to validate all related mocks, not just the one explicitly specified.
To isolate assertions to the intended mock object without affecting its dependencies, utilize the Returns overload with a Func<TResult> parameter type. This approach prevents JustMock from creating automatic dependencies between the mocks.
Example
Consider the scenario where you have a mock SqlConnection object and a mock SqlTransaction object:
// Arrange
SqlConnection sqlConnection = Mock.Create<SqlConnection>();
SqlTransaction sqlTransaction = Mock.Create<SqlTransaction>();
Mock.Arrange(() => new SqlConnection()).Returns(sqlConnection);
Mock.Arrange(() => sqlConnection.BeginTransaction()).Returns(sqlTransaction);
// Assert
Mock.Assert(sqlConnection, "Problem in Connection"); In the sample code when asserting sqlConnection will automatically assert sqlTransaction. By changing the arrangement to use a Returns overload with Func<TResult> the assertion against sqlConnection will not inadvertently include sqlTransaction. Here is the code:
Mock.Arrange(() => sqlConnection.BeginTransaction()).Returns(() => sqlTransaction);