Add cycle detection tests

Author: Hendrik van Antwerpen

stack-graphs/tests/it/cycles.rs

@@ -5,8 +5,13 @@
 // Please see the LICENSE-APACHE or LICENSE-MIT files in this distribution for license details.
 // ------------------------------------------------------------------------------------------------
 
+use stack_graphs::cycles::AppendingCycleDetector;
+use stack_graphs::cycles::JoiningCycleDetector;
 use stack_graphs::graph::StackGraph;
 use stack_graphs::partial::PartialPaths;
+use stack_graphs::stitching::Database;
+use stack_graphs::CancelAfterDuration;
+use std::time::Duration;
 
 use crate::util::*;
 
@@ -123,3 +128,67 @@ fn two_steps_forward_one_step_back_path_is_productive() {
 
     assert!(p.is_productive(&graph, &mut partials));
 }
+
+// ----------------------------------------------------------------------------
+// cycle detection
+
+#[test]
+fn appending_simple_identity_cycle_is_detected() {
+    let mut graph = StackGraph::new();
+    let file = graph.add_file("test").unwrap();
+    let r = StackGraph::root_node();
+    let s = create_scope_node(&mut graph, file, false);
+    let foo_ref = create_push_symbol_node(&mut graph, file, "foo", false);
+    let foo_def = create_pop_symbol_node(&mut graph, file, "foo", false);
+
+    let mut partials = PartialPaths::new();
+    create_partial_path_and_edges(&mut graph, &mut partials, &[r, foo_ref, s, foo_def, r]).unwrap();
+
+    // test appending cycle detector
+    {
+        let mut cd = AppendingCycleDetector::from_node(r);
+        assert!(cd.appended(&graph, &mut partials, foo_ref));
+        assert!(cd.appended(&graph, &mut partials, s));
+        assert!(cd.appended(&graph, &mut partials, foo_def));
+        assert!(!cd.appended(&graph, &mut partials, r));
+    }
+
+    // test termination of path finding
+    {
+        let mut path_count = 0usize;
+        let cancellation_flag = CancelAfterDuration::new(Duration::from_secs(10));
+        let result = partials.find_minimal_partial_path_set_in_file(
+            &graph,
+            file,
+            &cancellation_flag,
+            |_, _, _| path_count += 1,
+        );
+        assert!(result.is_ok());
+        assert_eq!(0, path_count);
+    }
+}
+
+#[test]
+fn joining_simple_identity_cycle_is_detected() {
+    let mut graph = StackGraph::new();
+    let file = graph.add_file("test").unwrap();
+    let r = StackGraph::root_node();
+    let s = create_scope_node(&mut graph, file, true);
+    let foo_ref = create_push_symbol_node(&mut graph, file, "foo", false);
+    let foo_def = create_pop_symbol_node(&mut graph, file, "foo", false);
+
+    let mut partials = PartialPaths::new();
+    let p0 = create_partial_path_and_edges(&mut graph, &mut partials, &[r, foo_ref, s]).unwrap();
+    let p1 = create_partial_path_and_edges(&mut graph, &mut partials, &[s, foo_def, r]).unwrap();
+
+    let mut db = Database::new();
+    let p0 = db.add_partial_path(&graph, &mut partials, p0);
+    let p1 = db.add_partial_path(&graph, &mut partials, p1);
+
+    // test joining cycle detector
+    {
+        let mut cd =
+            JoiningCycleDetector::from_partial_path_handle(&graph, &mut partials, &mut db, p0);
+        assert!(!cd.joined(&graph, &mut partials, &mut db, p1.into()));
+    }
+}