diff --git a/doc/fixing_tests.md b/doc/fixing_tests.md
index df3d5d4be..84f5fcbb4 100644
--- a/doc/fixing_tests.md
+++ b/doc/fixing_tests.md
@@ -29,3 +29,13 @@ executing
 When the `yes` option is provided, `meld` is automatically invoked
 whenever there is discrepancy between the produced and expected
 outputs. `meld` can also be used to repair the problems.
+
+Here is the list of directories where produced output is compared with
+the expected output (stored in a `*.expected.out` file).
+
+- [`tests/lean`](../tests/lean)
+- [`tests/lean/interactive`](../tests/lean/interactive)
+
+Remark: in the directory `tests/lean/interactive`, the input test files have extension `.input`.
+They simulate commands sent from Emacs to Lean.
+The `.lean` files in this directory are used to simulate files opened by the user.
\ No newline at end of file