[ENH] add placeholder test suite for neural networks

sktime/networks/tests/test_all_networks.py

@@ -0,0 +1,33 @@
+"""Unit tests for all neural networks."""
+
+from sktime.tests.test_all_estimators import BaseFixtureGenerator, QuickTester
+
+
+class NetworkFixtureGenerator(BaseFixtureGenerator):
+    """Fixture generator for classifier tests.
+
+    Fixtures parameterized
+    ----------------------
+    estimator_class: estimator inheriting from BaseObject
+        ranges over estimator classes not excluded by EXCLUDE_ESTIMATORS, EXCLUDED_TESTS
+    estimator_instance: instance of estimator inheriting from BaseObject
+        ranges over estimator classes not excluded by EXCLUDE_ESTIMATORS, EXCLUDED_TESTS
+        instances are generated by create_test_instance class method
+    scenario: instance of TestScenario
+        ranges over all scenarios returned by retrieve_scenarios
+    """
+
+    # note: this should be separate from TestAllNetworks
+    #   additional fixtures, parameters, etc should be added here
+    #   TestAllNetworks should contain the tests only
+
+    estimator_type_filter = "network"
+
+
+class TestAllNetworks(NetworkFixtureGenerator, QuickTester):
+    """Module level tests for all sktime neural networks."""
+
+    def test_dummy(self, estimator_instance):
+        """Dummy test to act as placeholder."""
+        # check if multivariate input raises error for univariate regressors
+        assert 42 == 42