Add property testing example using hypothesis library

- use `given` and `st.integers` to sample from a range of ints
- use `example` to explicitly include an input
- use `assume` to remove undesired inputs from sampling
- use `composite` to construct more complicated samples efficiently

.github/workflows/ci.yml

@@ -29,6 +29,8 @@ jobs:
         # setuptools_scm requires a non-shallow clone of the repository
         fetch-depth: 0
 
+    - uses: tlambert03/setup-qt-libs@v1
+
     - name: Linux setup
       if: runner.os == 'Linux'
       # qt requires some system libraries on linux that are not installed by default

pyproject.toml

@@ -39,7 +39,8 @@ tests = [
     "pytest-randomly",
     "pytest-qt",
     "pytest-xvfb",
-    "ipytest"
+    "ipytest",
+    "hypothesis",
 ]
 
 # Command line scripts installed as part of the installation

tests/test_board_property.py

@@ -0,0 +1,42 @@
+from __future__ import annotations
+from effective_software_testing.board import Board
+from hypothesis import given, assume, example
+import hypothesis.strategies as st
+
+
+# sample n from integers in the range 0 <= n <= 99
+@given(n=st.integers(min_value=0, max_value=99))
+@example(n=3)  # always include n=3
+def test_property_empty_board_game_not_over(n: int) -> None:
+    board = Board(n)
+    assert board.n == n
+    assert board.game_is_over is False
+
+
+@given(n=st.integers(1, 12), x=st.integers(0, 11), y=st.integers(0, 11))
+def test_property_empty_board_is_empty_with_assume(n: int, x: int, y: int) -> None:
+    assume(x < n)  # if x >= n we re-sample n,x,y
+    assume(y < n)
+    # assume works but quickly gets inefficient if many inputs do not satisfy our assumptions
+    board = Board(n)
+    assert board.square(x, y) is None
+
+
+# using composite is a more efficient way to sample from our desired distribution of values
+@st.composite
+def sample_valid_n_x_y(draw: st.DrawFn) -> tuple[int, int, int]:
+    max_board_n = 12
+    n = draw(st.integers(1, max_board_n))
+    x = draw(st.integers(0, n - 1))
+    y = draw(st.integers(0, n - 1))
+    return n, x, y
+
+
+@given(n_x_y=sample_valid_n_x_y())
+def test_property_empty_board_is_empty_with_composite(
+    n_x_y: tuple[int, int, int]
+) -> None:
+    # no assume required here as all the x,y we generate are < n
+    n, x, y = n_x_y
+    board = Board(n)
+    assert board.square(x, y) is None