Wolfram Notebooks provide a convenient interface in which to write and run tests of your code.

In the Mathematica menus, click File ▶ New ▶ Programmatic Notebook ▶ Testing Notebook. It will bring up a testing notebook. (The notebook depicted here has also been saved using File ▶ Save As... with name MyTests.)

Click the New button to insert a test into the notebook.

In the "Input" cell, type or paste the input for your test. In the "Expected Output" cell, type or paste what the output should be.

If messages are expected to be generated upon running the tests, add them using the Add Messages button. You can also add options to individual tests, such as MemoryConstraint, SameTest, TestID and TimeConstraint, using the drop-down to the right of the Add Options button.

To define values or run setup code outside of a test, insert an "Environ" cell by clicking More ▶ Insert Environ Cell before the test.

This creates an "Environ" cell with a light-gray background. Expressions in an "Environ" cell are evaluated during the test run, while content in a regular input cell is ignored.

This section demonstrates running all tests in a given notebook.

Clicking the Run button will evaluate all tests in the testing notebook. The test results are inserted into the individual tests as they are evaluated, and upon completion of the test run, a summary of the test report is inserted at the top of the notebook. The following notebook displays the four possible test outcomes: Success, Failure, Message Failure and Error. The Clear Test Results button may be used to clear test results from the notebook.

The test report summary details the total number of tests run as well as the number of successes, errors, failures due to wrong results and failures due to messages. Additionally, a summary bar depicts the test results and has two modes for ordering the test results: by status and by sequence. When the total number of tests in a testing notebook is 50 or fewer, every individual tab in the summary bar links to its appropriate test. In the lower-right corner, there are two buttons that find the previous and next failed tests relative to the cursor position.

Click More ▶ Save As .wlt to save the tests in the notebook to a .wlt file. A file save chooser will be generated, allowing you to choose the file name and save it to a directory.

Here, the file name was chosen to be MyTests2 and it was saved to the directory C:\\Users\\xyz\\Desktop. This makes a report for that file.

Here are the properties of the report.

Here are the test result rules.

This shows the expected output and actual output for the first failed test. For this test file, there is just one failed test.

Click More ▶ Assign TestIDs to assign a TestID to each test in the notebook.

Here is a test cell group with a TestID assigned.

You might want to convert a notebook of inputs, messages and outputs into a test notebook. With that notebook being the input notebook, click Window ▶ Toolbar ▶ Testing. A docked cell will then be added to the top of that notebook. Then click the button Convert to Testing Notebook.

Cells with the "Code" cell style are converted to "Environ" cells in the testing notebook.