chore(lib): warn about overflow and add Rust coverage

.github/workflows/lint.yml

@@ -22,8 +22,6 @@ jobs:
 
     - name: Install Python
       uses: actions/setup-python@v5
-      with:
-        python-version: '3.11'
 
     - name: Install pre-commit
       run: pip install pre-commit

.github/workflows/publish.yml

@@ -26,8 +26,6 @@ jobs:
 
     - name: Install Python
       uses: actions/setup-python@v5
-      with:
-        python-version: '3.10'
 
     - name: Build wheels
       uses: PyO3/maturin-action@v1
@@ -57,7 +55,6 @@ jobs:
     - name: Install Python
       uses: actions/setup-python@v5
       with:
-        python-version: '3.11'
         architecture: ${{ matrix.target }}
 
     - name: Build wheels

.github/workflows/test.yml

@@ -69,7 +69,8 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v4
 
-    - uses: actions/setup-python@v5
+    - name: Setup Python
+      uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.pyversion }}
 
@@ -82,6 +83,34 @@ jobs:
     - name: Run Cargo test
       run: cargo test
 
+  cargo-tarpaulin:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+
+    - name: Setup Python
+      uses: actions/setup-python@v5
+
+    - name: Install NumPy
+      run: pip install numpy
+
+    - name: Install Rust
+      uses: dtolnay/rust-toolchain@stable
+
+    - uses: taiki-e/install-action@v2
+      with:
+        tool: cargo-tarpaulin@0.31.2
+
+    - name: Generate code coverage
+      run: cargo tarpaulin --verbose --timeout 120 --out xml
+
+    - name: Upload to codecov.io
+      uses: codecov/codecov-action@v4
+      with:
+        token: ${{ secrets.DIFFERT_CODECOV_TOKEN }}
+        fail_ci_if_error: true
+
   python-benchmark:
     runs-on: ubuntu-latest
     permissions:
@@ -92,7 +121,6 @@ jobs:
 
     - uses: actions/setup-python@v5
       with:
-        python-version: '3.11'
         cache: pip
         cache-dependency-path: uv.lock
 
@@ -205,8 +233,6 @@ jobs:
       uses: actions/checkout@v4
 
     - uses: actions/setup-python@v5
-      with:
-        python-version: '3.11'
 
     - name: Install NumPy
       run: pip install numpy

.python-version

@@ -1 +1 @@
-3.11.8
+3.11

differt-core/src/rt/graph.rs

@@ -317,7 +317,7 @@
                     let from_in_graph = from < num_nodes;
                     let to_in_graph = to < num_nodes;
 
-                    match (from_in_graph, to_in_graph) {
+                    (match (from_in_graph, to_in_graph) {
                         (true, true) => {
                             //This solution was obtained thanks to user @ronno, see:
                             // https://math.stackexchange.com/a/4874894/1297520.
@@ -326,38 +326,48 @@
                             let num_nodes_minus_1 = num_nodes.saturating_sub(1);
                             if from != to {
                                 num_nodes_minus_1
-                                    .saturating_pow(depth_minus_1)
-                                    .saturating_add_signed(if depth_minus_1 % 2 == 0 {
-                                        -1
-                                    } else {
-                                        1
+                                    .checked_pow(depth_minus_1)
+                                    .and_then(|num| {
+                                        num.checked_add_signed(if depth_minus_1 % 2 == 0 {
+                                            -1
+                                        } else {
+                                            1
+                                        })
                                     })
-                                    / num_nodes
+                                    .map(|num| num / num_nodes)
                             } else {
                                 num_nodes_minus_1
-                                    .saturating_pow(depth_minus_2)
-                                    .saturating_add_signed(if depth_minus_2 % 2 == 0 {
-                                        -1
-                                    } else {
-                                        1
+                                    .checked_pow(depth_minus_2)
+                                    .and_then(|num| {
+                                        num.checked_add_signed(if depth_minus_2 % 2 == 0 {
+                                            -1
+                                        } else {
+                                            1
+                                        })
                                     })
-                                    * num_nodes_minus_1
-                                    / num_nodes
+                                    .map(|num| (num / num_nodes) * num_nodes_minus_1)
                             }
                         },
                         (false, false) => {
                             // (num_nodes) * (num_nodes - 1)^(num_intermediate_nodes - 1)
-                            (num_nodes).saturating_mul(
-                                num_nodes
-                                    .saturating_sub(1)
-                                    .saturating_pow(num_intermediate_nodes.saturating_sub(1)),
-                            )
+                            num_nodes
+                                .saturating_sub(1)
+                                .checked_pow(num_intermediate_nodes.saturating_sub(1))
+                                .and_then(|num| num_nodes.checked_mul(num))
                         },
                         _ => {
                             // (num_nodes - 1)^num_intermediate_nodes
-                            (num_nodes.saturating_sub(1)).saturating_pow(num_intermediate_nodes)
+                            (num_nodes.saturating_sub(1)).checked_pow(num_intermediate_nodes)
                         },
-                    }
+                    })
+                    .unwrap_or_else(|| {
+                        log::warn!(
+                            "OverflowError: overflow occurred when computing the total number of \
+                             paths, defaulting to maximum value {}.",
+                            usize::MAX
+                        );
+                        usize::MAX
+                    })
                 },
             };
 

differt-core/tests/rt/test_graph.py

@@ -83,6 +83,27 @@ def test_all_keyword_only_parameters(self) -> None:
         ):
             _ = graph.all_paths(0, 1, 0, True)  # noqa: FBT003
 
+    @pytest.mark.parametrize(
+        ("num_nodes", "depth"),
+        [
+            (15, 2),
+            (25, 3),
+            (11, 4),
+        ],
+    )
+    def test_all_paths_count_from_complete_graph(
+        self,
+        num_nodes: int,
+        depth: int,
+    ) -> None:
+        graph = CompleteGraph(num_nodes)
+        from_, to = num_nodes, num_nodes + 1
+        paths = graph.all_paths(from_, to, depth + 2, include_from_and_to=False)
+        num_paths = sum(1 for _ in paths)
+        assert num_paths == num_nodes * (num_nodes - 1) ** (depth - 1)
+        array = graph.all_paths_array(from_, to, depth + 2, include_from_and_to=False)
+        assert array.shape == (num_paths, depth)
+
     @pytest.mark.parametrize(
         ("num_nodes", "depth"),
         [
@@ -91,7 +112,7 @@ def test_all_keyword_only_parameters(self) -> None:
             (10, 3),
         ],
     )
-    def test_all_paths_count_from_complete_graph(
+    def test_all_paths_count_from_di_graph(
         self,
         num_nodes: int,
         depth: int,
@@ -103,3 +124,28 @@ def test_all_paths_count_from_complete_graph(
         assert num_paths == num_nodes * (num_nodes - 1) ** (depth - 1)
         array = graph.all_paths_array(from_, to, depth + 2, include_from_and_to=False)
         assert array.shape == (num_paths, depth)
+
+    @pytest.mark.parametrize(
+        ("num_nodes", "depth"),
+        [
+            (10, 100),
+            (50_000, 10),
+        ],
+    )
+    def test_all_paths_count_from_complete_graph_overflow(
+        self,
+        num_nodes: int,
+        depth: int,
+        caplog: pytest.LogCaptureFixture,
+    ) -> None:
+        graph = CompleteGraph(num_nodes)
+        from_, to = num_nodes, num_nodes + 1
+        _ = graph.all_paths(from_, to, depth + 2, include_from_and_to=False)
+
+        for record in caplog.records:
+            assert record.levelname == "WARNING"
+
+        assert (
+            "OverflowError: overflow occurred when computing the total number of paths"
+            in caplog.text
+        )