relevant tests skip if cvxpy or dask is not installed

.github/CHANGELOG.md

@@ -398,6 +398,9 @@ and requirements-ci.txt (unpinned). This latter would be used by the CI.
 
 <h3>Bug fixes</h3>
 
+* Dask and CVXPY dependent tests are skipped if those packages are not installed.
+[(#1617)](https://github.com/PennyLaneAI/pennylane/pull/1617)
+
 * The `qml.layer` template now works with tensorflow variables.
 [(#1615)](https://github.com/PennyLaneAI/pennylane/pull/1615)
 

tests/circuit_graph/test_circuit_graph_hash.py

@@ -614,6 +614,7 @@ def circuit2(x, y):
 
         assert circuit_hash_1 != circuit_hash_2
 
+    @pytest.mark.usefixtures("skip_if_no_dask_support")
     def test_compiled_program_was_stored(self):
         """Test that QVM device stores the compiled program correctly"""
         dev = qml.device("default.qubit", wires=3)

tests/collections/test_qnode_collection.py

@@ -174,9 +174,13 @@ class TestEvalation:
     """Tests for the QNodeCollection evaluation"""
 
     @pytest.mark.parametrize("interface", ["autograd"])
-    def test_eval_autograd(self, qnodes, parallel, interface):
+    def test_eval_autograd(self, qnodes, parallel, interface, dask_support):
         """Test correct evaluation of the QNodeCollection using
         the Autograd interface"""
+
+        if (not dask_support) and (parallel):
+            pytest.skip("Skipped, no dask support")
+
         qnode1, qnode2 = qnodes
         qc = qml.QNodeCollection([qnode1, qnode2])
         params = [0.5643, -0.45]

tests/conftest.py

@@ -110,6 +110,28 @@ def gaussian_device_4modes():
     return DummyDevice(wires=4)
 
 
+############### Package Support ##########################
+
+
+@pytest.fixture(scope="session")
+def dask_support():
+    """Boolean fixture for dask support"""
+    try:
+        import dask
+
+        dask_support = True
+    except ImportError as e:
+        dask_support = False
+
+    return dask_support
+
+
+@pytest.fixture()
+def skip_if_no_dask_support(dask_support):
+    if not dask_support:
+        pytest.skip("Skipped, no dask support")
+
+
 @pytest.fixture(scope="session")
 def torch_support():
     """Boolean fixture for PyTorch support"""
@@ -155,6 +177,9 @@ def skip_if_no_jax_support():
     pytest.importorskip("jax")
 
 
+#######################################################################
+
+
 @pytest.fixture(scope="module", params=[1, 2, 3])
 def seed(request):
     """Different seeds."""

tests/kernels/test_kernels.py

@@ -23,6 +23,24 @@
 import sys
 
 
+@pytest.fixture()
+def cvxpy_support():
+    try:
+        import cvxpy
+
+        cvxpy_support = True
+    except:
+        cvxpy_support = False
+
+    return cvxpy_support
+
+
+@pytest.fixture()
+def skip_if_no_cvxpy_support(cvxpy_support):
+    if not cvxpy_support:
+        pytest.skip("Skipped, no cvxpy support")
+
+
 @qml.template
 def _simple_ansatz(x, params):
     """A simple quantum circuit ansatz."""
@@ -361,18 +379,13 @@ def test_flip_matrix(self, input, expected_output):
             (np.array([[0, 1.000001], [1, 0]]), True, np.array([[1, 1], [1, 1]])),
         ],
     )
+    @pytest.mark.usefixtures("skip_if_no_cvxpy_support")
     def test_closest_psd_matrix(self, input, fix_diagonal, expected_output):
         """Test obtaining the closest positive semi-definite matrix using a semi-definite program."""
         try:
             import cvxpy as cp
 
             output = kern.closest_psd_matrix(input, fix_diagonal=fix_diagonal, feastol=1e-10)
-        except ModuleNotFoundError:
-            pytest.skip(
-                "cvxpy seems to not be installed on the system."
-                "It is required for qml.kernels.closest_psd_matrix"
-                " and can be installed via `pip install cvxpy`."
-            )
         except cp.error.SolverError:
             pytest.skip(
                 "The cvxopt solver seems to not be installed on the system."
@@ -402,6 +415,7 @@ def test_closest_psd_matrix_import_error(self, input, mocker):
             (np.diag([1, -1]), "I am not a solver"),
         ],
     )
+    @pytest.mark.usefixtures("skip_if_no_cvxpy_support")
     def test_closest_psd_matrix_solve_error(self, input, solver):
         """Test verbose error raising if problem.solve crashes."""
         with pytest.raises(Exception) as solve_error:

tests/tape/test_qnode.py

@@ -770,6 +770,7 @@ def func(x, y):
         assert func.qtape is not old_tape
 
 
+@pytest.mark.usefixtures("skip_if_no_dask_support")
 class TestQNodeCollection:
     """Unittests for the QNodeCollection"""