feat(nodes): add tests for depth-first execution

tests/nodes/test_graph_execution_state.py

@@ -121,3 +121,78 @@ def test_graph_state_collects(mock_services):
     assert isinstance(n6[0], CollectInvocation)
 
     assert sorted(g.results[n6[0].id].collection) == sorted(test_prompts)
+
+
+def test_graph_state_prepares_eagerly(mock_services):
+    """Tests that all prepareable nodes are prepared"""
+    graph = Graph()
+
+    test_prompts = ["Banana sushi", "Cat sushi"]
+    graph.add_node(PromptCollectionTestInvocation(id="prompt_collection", collection=list(test_prompts)))
+    graph.add_node(IterateInvocation(id="iterate"))
+    graph.add_node(PromptTestInvocation(id="prompt_iterated"))
+    graph.add_edge(create_edge("prompt_collection", "collection", "iterate", "collection"))
+    graph.add_edge(create_edge("iterate", "item", "prompt_iterated", "prompt"))
+
+    # separated, fully-preparable chain of nodes
+    graph.add_node(PromptTestInvocation(id="prompt_chain_1", prompt="Dinosaur sushi"))
+    graph.add_node(PromptTestInvocation(id="prompt_chain_2"))
+    graph.add_node(PromptTestInvocation(id="prompt_chain_3"))
+    graph.add_edge(create_edge("prompt_chain_1", "prompt", "prompt_chain_2", "prompt"))
+    graph.add_edge(create_edge("prompt_chain_2", "prompt", "prompt_chain_3", "prompt"))
+
+    g = GraphExecutionState(graph=graph)
+    g.next()
+
+    assert "prompt_collection" in g.source_prepared_mapping
+    assert "prompt_chain_1" in g.source_prepared_mapping
+    assert "prompt_chain_2" in g.source_prepared_mapping
+    assert "prompt_chain_3" in g.source_prepared_mapping
+    assert "iterate" not in g.source_prepared_mapping
+    assert "prompt_iterated" not in g.source_prepared_mapping
+
+
+def test_graph_executes_depth_first(mock_services):
+    """Tests that the graph executes depth-first, executing a branch as far as possible before moving to the next branch"""
+    graph = Graph()
+
+    test_prompts = ["Banana sushi", "Cat sushi"]
+    graph.add_node(PromptCollectionTestInvocation(id="prompt_collection", collection=list(test_prompts)))
+    graph.add_node(IterateInvocation(id="iterate"))
+    graph.add_node(PromptTestInvocation(id="prompt_iterated"))
+    graph.add_node(PromptTestInvocation(id="prompt_successor"))
+    graph.add_edge(create_edge("prompt_collection", "collection", "iterate", "collection"))
+    graph.add_edge(create_edge("iterate", "item", "prompt_iterated", "prompt"))
+    graph.add_edge(create_edge("prompt_iterated", "prompt", "prompt_successor", "prompt"))
+
+    g = GraphExecutionState(graph=graph)
+    n1 = invoke_next(g, mock_services)
+    n2 = invoke_next(g, mock_services)
+    n3 = invoke_next(g, mock_services)
+    n4 = invoke_next(g, mock_services)
+
+    # Because ordering is not guaranteed, we cannot compare results directly.
+    # Instead, we must count the number of results.
+    def get_completed_count(g, id):
+        ids = [i for i in g.source_prepared_mapping[id]]
+        completed_ids = [i for i in g.executed if i in ids]
+        return len(completed_ids)
+
+    # Check at each step that the number of executed nodes matches the expectation for depth-first execution
+    assert get_completed_count(g, "prompt_iterated") == 1
+    assert get_completed_count(g, "prompt_successor") == 0
+
+    n5 = invoke_next(g, mock_services)
+
+    assert get_completed_count(g, "prompt_iterated") == 1
+    assert get_completed_count(g, "prompt_successor") == 1
+
+    n6 = invoke_next(g, mock_services)
+
+    assert get_completed_count(g, "prompt_iterated") == 2
+    assert get_completed_count(g, "prompt_successor") == 1
+
+    n7 = invoke_next(g, mock_services)
+
+    assert get_completed_count(g, "prompt_iterated") == 2
+    assert get_completed_count(g, "prompt_successor") == 2