Add setup and teardown functionality

testing.pl

@@ -75,6 +75,39 @@
 
 After running, `run_tests/1` exits with a status code of 0 if all tests that were run succeeded and
 1 otherwise. This makes it possible to check if tests pass inside scripts.
+
+# Setup and Teardown
+
+The testing framework supports setup and teardown hooks that run before and after each test:
+
+- `test_setup/0`: Runs before each test. Use this to initialize test fixtures or state.
+- `test_teardown/0`: Runs after each test, regardless of whether the test succeeds or fails.
+
+These predicates are optional. If they are not defined, the tests run normally without setup/teardown.
+
+Example:
+
+```prolog
+:- use_module(testing).
+:- use_module(my_module).
+
+:- dynamic(test_state/1).
+
+test_setup :-
+    retractall(test_state(_)),
+    assert(test_state(initialized)).
+
+test_teardown :-
+    retractall(test_state(_)).
+
+test("test with setup", (
+    test_state(initialized),
+    example(1)
+)).
+```
+
+The teardown hook is guaranteed to run even if the test fails or throws an exception, ensuring
+proper cleanup of resources.
 */
 
 % SPDX-License-Identifier: Unlicense
@@ -171,7 +204,12 @@
 run_tests_([], _, Success, Success).
 run_tests_([test(Name, Goal)|Tests], Color, Success0, Success) :-
     portray(format_("  test \"~s\" ... ", [Name])),
-    (   catch(call(Goal), Exception, true) ->
+    run_single_test_(Goal, Color, Success0, Success1),
+    portray("\n"),
+    run_tests_(Tests, Color, Success1, Success).
+
+run_single_test_(Goal, Color, Success0, Success1) :-
+    (   catch(call_with_setup_teardown_(Goal), Exception, true) ->
         (   nonvar(Exception) ->
             portray(ansi(Color, red)),
             (   Exception = error(_,_) ->
@@ -185,9 +223,33 @@
         )
     ;   portray((ansi(Color, red), "failed", ansi(Color, reset))),
         Success1 = false
+    ).
+
+call_with_setup_teardown_(Goal) :-
+    (   Goal = Module:_ ->
+        SetupGoal = Module:test_setup,
+        TeardownGoal = Module:test_teardown
+    ;   SetupGoal = test_setup,
+        TeardownGoal = test_teardown
     ),
-    portray("\n"),
-    run_tests_(Tests, Color, Success1, Success).
+    catch(
+        (
+            call_setup_(SetupGoal),
+            catch(
+                (call(Goal), call_teardown_(TeardownGoal)),
+                TestException,
+                (call_teardown_(TeardownGoal), throw(TestException))
+            )
+        ),
+        SetupException,
+        throw(SetupException)
+    ).
+
+call_setup_(SetupGoal) :-
+    catch(call(SetupGoal), error(existence_error(procedure, _), _), true).
+
+call_teardown_(TeardownGoal) :-
+    catch(call(TeardownGoal), error(existence_error(procedure, _), _), true).
 
 ansi(true, reset) --> "\x1b\[0m".
 ansi(true, red) --> "\x1b\[31;1m".