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Using Test Conditions in Database Unit Tests

In a typical database unit test, a Transact-SQL test script runs and returns an instance of the ExecutionResult class. The instance of this class contains a DataSet, the execution time, and the rows affected by the script. All of this information is collected during execution of the script. These results can be evaluated within the Transact-SQL script by using the RAISERROR function, or they can be evaluated by using test conditions. Visual Studio Premium provides a set of predefined test conditions for you to use.

The following table lists the predefined test conditions that you can add by using the Test Conditions pane in the Database Unit Test designer.

Test Condition

Test Condition Description

Data Checksum

Fails if the checksum of the result set returned from the Transact-SQL script does not match the expected checksum. For more information, see Specifying a Data Checksum.

NoteNote
This test condition is not recommended if you are returning data that will vary between test runs. For example, if your result set contains generated dates or times, or contains identity columns, your tests will fail because the checksum will be different on each run.

Empty ResultSet

Fails if the result set returned from the Transact-SQL script is not empty.

Execution Time

Fails if the Transact-SQL test script takes longer than expected to execute. The default execution time is 30 seconds.

The execution time applies to the test script test only, not to the pre-test script or the post-test script.

Expected Schema

Fails if the columns and data types of the result set do not match those specified for the test condition. You must specify a schema through the properties of the test condition. For more information, see Specifying an Expected Schema.

Inconclusive

Always produces a test with a result of Inconclusive. This is the default condition added to every test. This test condition is included to indicate that test verification has not been implemented. Delete this test condition from your test after you have added other test conditions.

Not Empty ResultSet

Fails if the result set is empty. You can use this test condition or the EmptyResultSet with the Transact-SQL @@RAISERROR function in your test script to test whether an update worked correctly. For example, you can save pre-update values, run the update, compare post-update values, and raise an error if you do not get the expected results.

Row Count

Fails if the result set does not contain the expected number of rows.

Scalar Value

Fails if a particular value in the result set does not equal the specified value. The default Expected value is null.

NoteNote

The Execution Time test condition specifies a time limit under which the Transact-SQL test script must run. If this time limit is exceeded, the test fails. Test results also include a Duration statistic, which differs from the Execution Time test condition. The Duration statistic includes not only the execution time but also the time to connect to the database two times; the time to run any other test scripts, such as the pre-test script and the post-test script; and the time to run the test conditions. Therefore, a test can pass even if its duration is longer than its execution time.

The reported Duration does not include time used for data generation and schema deployment because they occur before the tests are run. To view the test duration, select a test run in the Test Results window, right-click, and choose View Test Results Details.

You can add test conditions to database unit tests by using the Test Conditions pane of the Database Unit Test Designer. For more information, see How to: Add Test Conditions to Database Unit Tests.

You can also edit your test-method code directly to add more functionality. For more information, see How to: Open a Database Unit Test to Edit and How to: Write a Database Unit Test that Runs within the Scope of a Single Transaction. For example, you can add functionality to a test method by adding Assert statements. For more information, see Using Transact-SQL Assertions in Database Unit Tests.

You might create database unit tests to test behavior that should not succeed. These expected failures are sometimes referred to as negative testing. Some examples would include the following:

  • Verify that a stored procedure that deletes a customer's data fails if you specify an invalid customer ID

  • Verify that a stored procedure that fills an order fails if the order was never placed or if the order was already filled

  • Verify that a stored procedure that cancels an order cannot cancel completed orders or orders that were already canceled

You can define database unit tests for stored procedures that throw expected SQL exceptions. You can add an attribute to the unit test method to indicate which exception or exceptions are expected. By doing this, you prevent the test from failing when the exception occurs.

To mark a database unit test method with expected exceptions, add the following attribute:

[ExpectedSqlException(MessageNumber = nnnnn, Severity = x, MatchFirstError = false, State = y)]

Where:

  • nnnnn is the number of the expected message, for example 14025

  • x is the severity of the expected exception

  • y is the state of the expected exception

Any unspecified parameters are ignored. You pass these parameters to the RAISERROR statement in your database code. If you specify MatchFirstError = false, then the attribute will match any of the SqlErrors in the exception. The default behavior (MatchFirstError = true) is to only match the first error that occurs.

For an example of how to use expected exceptions and a negative database unit test, see Walkthrough: Creating and Running a Database Unit Test.

After you add a Data Checksum test condition to your database unit test, you must configure the expected checksum by using the following procedure:

To specify an expected checksum

  1. In the list of test conditions, click the Data Checksum test condition for which you want to specify a checksum.

  2. Open the Properties window by pressing F4. You can also open the View menu and click Properties Window.

  3. (Optional) You might want to change the (Name) property of the test condition to be more descriptive.

  4. In the Configuration property, click the browse () button.

    The Configuration for TestConditionName dialog box appears.

  5. Specify a connection to the database that you want to test. For more information, see How to: Create a Database Connection.

  6. By default, the Transact-SQL body of your test appears in the edit pane. You can modify the code, if necessary, to produce the expected results. For example, if your test has code in the pre-test, you might have to add that code.

    Important noteImportant

    If you modify a checksum condition for which you had previously specified a checksum, any changes that you made in the edit pane are not saved. You must make those changes again before you click Retrieve.

  7. Click Retrieve.

    The Transact-SQL is executed against the specified database connection and the results appear in the dialog box.

  8. If the results match the expected results of your test, click OK. Otherwise modify the Transact-SQL body and repeat steps 6, 7, and 8 until the results are as expected.

    The Value column of the test condition displays the value of the expected checksum.

After you add an Expected Schema test condition to your database unit test, you must configure the expected schema by using the following procedure:

To specify an expected schema

  1. In the list of test conditions, click the Expected Schema test condition for which you want to specify a schema.

  2. Open the Properties window by pressing F4. You can also open the View menu and click the Properties window.

  3. (Optional) You might want to change the (Name) property of the test condition to be more descriptive.

  4. In the Configuration property, click the browse () button.

    The Configuration for TestConditionName dialog box appears.

  5. Specify a connection to the database that you want to test. For more information, see How to: Create a Database Connection.

  6. By default, the Transact-SQL body of your test appears in the edit pane. You can modify the code, if necessary, to produce the expected results. For example, if your test has code in the pre-test, you might have to add that code.

    Important noteImportant

    If you modify an expected schema condition for which you had previously specified a schema, any changes that you made in the edit pane are not saved. You must make those changes again before you click Retrieve.

  7. Click Retrieve.

    The Transact-SQL is executed against the specified database connection and the results appear in the dialog box. Because you are verifying the schema, or shape, of the result set and not the values of the results, you do not have to see any data in the returned results, as long as the columns appear the way that you expect them to appear.

  8. If the results match the expected results of your test, click OK. Otherwise modify the Transact-SQL body and repeat steps 6, 7, and 8 until the results are as expected.

    The Value column of the test condition displays information about the expected schema. For example, it might say "Expected: 2 tables".

In addition to the six predefined test conditions, you can write new test conditions of your own. These test conditions will be displayed in the Test Conditions pane of the Database Unit Test Designer. For more information, see How to: Create Test Conditions for the Database Unit Test Designer

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