Fix phrasing about test to update in regression test exercise

Author: svenvanderburg

episodes/34-code-refactoring.md

@@ -87,8 +87,8 @@ the tests at all.
 ## Exercise: Write Regression Tests
 
 Modify the `analyse_data()` function not to plot a graph and return the data instead.
-Then, adapt the test file `test_analyse_data_mock_source.py` in the `tests` folder and
-add a regression test to verify the current output of `analyse_data()`. We will use this test
+Then, adapt the test `test_analyse_data_mock_source` in the `test_compute_data.py` in the `tests` folder and
+turn it into a regression test to verify the current output of `analyse_data()`. We will use this test
 in the remainder of this section to verify the output `analyse_data()` is unchanged each time
 we refactor or change code in the future.