public static void Main()
{
// This code shows that both service implementations have access to the database and
// that they still fulfill the same interface contract
IReportingService untestableReportingService = new Problem.ReportingService();
Console.WriteLine(
"Students enrolled, queried via the untestable service implementation: {0}",
untestableReportingService.GetNumberOfEnrolledStudents());
IReportingService testableReportingService = new Solution.ReportingService();
Console.WriteLine(
"Students enrolled, queried via the testable service implementation: {0}",
testableReportingService.GetNumberOfEnrolledStudents());
Console.ReadKey();
}
public void AlasHowDoYouTestThisWithoutAWorkingDatabaseConnection()
{
// Arrange
IReportingService reportingService = new ReportingService();
// Act
var actual = reportingService.GetNumberOfEnrolledStudents();
// The above will throw either a System.InvalidOperationException or a System.Data.SqlClient.SqlException,
// or simply time out depending on wether you use the entity framework LocalDB feature.
//
// This exception and or time out is 100% valid, since unit tests should never expect a working database connection.
//
// See the 'Solution' namespaces for how to solve this problem by completing removing the database
// connection from the picture while still retaining the ability to test the linq statements against
// a specific set of data.
// Assert - this line will never be reached
Assert.AreEqual(5, actual);
}
