[feat] Validate test case graph

reframe/frontend/dependency.py

@@ -3,6 +3,7 @@
 #
 
 import collections
+import itertools
 
 import reframe as rfm
 from reframe.core.exceptions import DependencyError
@@ -79,3 +80,49 @@ def print_deps(graph):
 
 def validate_deps(graph):
     """Validate dependency graph."""
+
+    # Reduce test case graph to a test name only graph; this disallows
+    # pseudo-dependencies as follows:
+    #
+    # (t0, e1) -> (t1, e1)
+    # (t1, e0) -> (t0, e0)
+    #
+    # This reduction step will result in a graph description with duplicate
+    # entries in the adjacency list; this is not a problem, cos they will be
+    # filtered out during the DFS traversal below.
+    test_graph = {}
+    for case, deps in graph.items():
+        test_deps = [d.check.name for d in deps]
+        try:
+            test_graph[case.check.name] += test_deps
+        except KeyError:
+            test_graph[case.check.name] = test_deps
+
+    # Check for cyclic dependencies in the test name graph
+    visited = set()
+    sources = set(test_graph.keys())
+    path = []
+
+    # Since graph may comprise multiple not connected subgraphs, we search for
+    # cycles starting from all possible sources
+    while sources:
+        unvisited = [(sources.pop(), None)]
+        while unvisited:
+            node, parent = unvisited.pop()
+            while path and path[-1] != parent:
+                path.pop()
+
+            adjacent = reversed(test_graph[node])
+            path.append(node)
+            for n in adjacent:
+                if n in path:
+                    cycle_str = '->'.join(path + [n])
+                    raise DependencyError(
+                        'found cyclic dependency between tests: ' + cycle_str)
+
+                if n not in visited:
+                    unvisited.append((n, node))
+
+            visited.add(node)
+
+        sources -= visited

unittests/test_policies.py

@@ -489,6 +489,7 @@ def test_build_deps(self):
 
         # Build dependencies and continue testing
         deps = dependency.build_deps(cases)
+        dependency.validate_deps(deps)
 
         # Check DEPEND_FULLY dependencies
         assert num_deps(deps, 'Test1_fully') == 8
@@ -587,3 +588,120 @@ def test_build_deps_unknown_source_env(self):
         # is not executed for eX
         deps = dependency.build_deps(executors.generate_testcases(checks))
         assert num_deps(deps, 'Test1_default') == 4
+
+    @rt.switch_runtime(fixtures.TEST_SITE_CONFIG, 'sys0')
+    def test_build_deps_empty(self):
+        assert {} == dependency.build_deps([])
+
+    def create_test(self, name):
+        test = rfm.RegressionTest()
+        test.name = name
+        test.valid_systems = ['*']
+        test.valid_prog_environs = ['*']
+        test.executable = 'echo'
+        test.executable_opts = [name]
+        return test
+
+    @rt.switch_runtime(fixtures.TEST_SITE_CONFIG, 'sys0')
+    def test_valid_deps(self):
+        #
+        #       t0       +-->t5<--+
+        #       ^        |        |
+        #       |        |        |
+        #   +-->t1<--+   t6       t7
+        #   |        |            ^
+        #   t2<------t3           |
+        #   ^        ^            |
+        #   |        |            t8
+        #   +---t4---+
+        #
+        t0 = self.create_test('t0')
+        t1 = self.create_test('t1')
+        t2 = self.create_test('t2')
+        t3 = self.create_test('t3')
+        t4 = self.create_test('t4')
+        t5 = self.create_test('t5')
+        t6 = self.create_test('t6')
+        t7 = self.create_test('t7')
+        t8 = self.create_test('t8')
+        t1.depends_on('t0')
+        t2.depends_on('t1')
+        t3.depends_on('t1')
+        t3.depends_on('t2')
+        t4.depends_on('t2')
+        t4.depends_on('t3')
+        t6.depends_on('t5')
+        t7.depends_on('t5')
+        t8.depends_on('t7')
+        dependency.validate_deps(
+            dependency.build_deps(
+                executors.generate_testcases([t0, t1, t2, t3, t4,
+                                              t5, t6, t7, t8])
+            )
+        )
+
+    @rt.switch_runtime(fixtures.TEST_SITE_CONFIG, 'sys0')
+    def test_cyclic_deps(self):
+        #
+        #       t0       +-->t5<--+
+        #       ^        |        |
+        #       |        |        |
+        #   +-->t1<--+   t6       t7
+        #   |   |    |            ^
+        #   t2  |    t3           |
+        #   ^   |    ^            |
+        #   |   v    |            t8
+        #   +---t4---+
+        #
+        t0 = self.create_test('t0')
+        t1 = self.create_test('t1')
+        t2 = self.create_test('t2')
+        t3 = self.create_test('t3')
+        t4 = self.create_test('t4')
+        t5 = self.create_test('t5')
+        t6 = self.create_test('t6')
+        t7 = self.create_test('t7')
+        t8 = self.create_test('t8')
+        t1.depends_on('t0')
+        t1.depends_on('t4')
+        t2.depends_on('t1')
+        t3.depends_on('t1')
+        t3.depends_on('t2')
+        t4.depends_on('t2')
+        t4.depends_on('t3')
+        t6.depends_on('t5')
+        t7.depends_on('t5')
+        t8.depends_on('t7')
+        deps = dependency.build_deps(
+            executors.generate_testcases([t0, t1, t2, t3, t4,
+                                          t5, t6, t7, t8])
+        )
+
+        with pytest.raises(DependencyError) as exc_info:
+            dependency.validate_deps(deps)
+
+        assert ('t4->t2->t1->t4' in str(exc_info.value) or
+                't2->t1->t4->t2' in str(exc_info.value) or
+                't1->t4->t2->t1' in str(exc_info.value) or
+                't1->t4->t3->t1' in str(exc_info.value) or
+                't4->t3->t1->t4' in str(exc_info.value) or
+                't3->t1->t4->t3' in str(exc_info.value))
+
+    @rt.switch_runtime(fixtures.TEST_SITE_CONFIG, 'sys0')
+    def test_cyclic_deps_by_env(self):
+        t0 = self.create_test('t0')
+        t1 = self.create_test('t1')
+        t1.depends_on('t0', rfm.DEPEND_EXACT, {'e0': ['e0']})
+        t0.depends_on('t1', rfm.DEPEND_EXACT, {'e1': ['e1']})
+        deps = dependency.build_deps(
+            executors.generate_testcases([t0, t1])
+        )
+        with pytest.raises(DependencyError) as exc_info:
+            dependency.validate_deps(deps)
+
+        assert ('t1->t0->t1' in str(exc_info.value) or
+                't0->t1->t0' in str(exc_info.value))
+
+    @rt.switch_runtime(fixtures.TEST_SITE_CONFIG, 'sys0')
+    def test_validate_deps_empty(self):
+        dependency.validate_deps({})