add test and traverse nodes when showing outs

dvc/command/pipeline.py

@@ -39,34 +39,37 @@ class CmdPipelineShow(CmdBase):
         target_stage = Stage.load(self.repo, target)
         G = get_pipeline(self.repo.pipelines, target_stage)
 
-        nodes = []
-        for stage in networkx.preorder_nodes(G, target_stage):
+        nodes = set()
+        for stage in networkx.dfs_preorder_nodes(G, target_stage):
             if commands:
                 if stage.cmd is None:
                     continue
-                nodes.append(stage.cmd)
+                nodes.add(stage.cmd)
             elif outs:
                 for out in stage.outs:
-                    nodes.append(str(out))
+                    nodes.add(str(out))
                 for dep in stage.deps:
-                    nodes.append(str(dep))
+                    nodes.add(str(dep))
             else:
-                nodes.append(stage.relpath)
+                nodes.add(stage.relpath)
 
         edges = []
-        for from_stage, to_stage in networkx.dfs_edges(G, target_stage):
-            if commands:
-                if to_stage.cmd is None:
-                    continue
-                edges.append((from_stage.cmd, to_stage.cmd))
-            elif outs:
-                for from_dep in from_stage.deps:
-                    for from_out in from_stage.outs:
-                        edges.append((str(from_out), str(from_dep)))
-            else:
-                edges.append((from_stage.relpath, to_stage.relpath))
 
-        return nodes, edges, networkx.is_tree(G)
+        if outs and not commands:
+            for stage in networkx.dfs_preorder_nodes(G, target_stage):
+                for dep in stage.deps:
+                    for out in stage.outs:
+                        edges.append((str(out), str(dep)))
+        else:
+            for from_stage, to_stage in networkx.dfs_edges(G, target_stage):
+                if commands:
+                    if to_stage.cmd is None:
+                        continue
+                    edges.append((from_stage.cmd, to_stage.cmd))
+                else:
+                    edges.append((from_stage.relpath, to_stage.relpath))
+
+        return list(nodes), edges, networkx.is_tree(G)
 
     def _show_ascii(self, target, commands, outs):
         from dvc.dagascii import draw

tests/func/test_pipeline.py

@@ -1,6 +1,7 @@
 import logging
 
 from dvc.main import main
+from dvc.command.pipeline import CmdPipelineShow
 from tests.basic_env import TestDvc
 from tests.func.test_repro import TestRepro
 from tests.func.test_repro import TestReproChangedDeepData
@@ -98,6 +99,29 @@ class TestPipelineShow(TestRepro):
         self.assertEqual(ret, 0)
 
 
+def test_disconnected_stage(tmp_dir, dvc, caplog):
+    tmp_dir.dvc_gen({"base": "base"})
+
+    dvc.add("base")
+    dvc.run(deps=["base"], outs=["derived1"], cmd="echo derived1 > derived1")
+    dvc.run(deps=["base"], outs=["derived2"], cmd="echo derived2 > derived2")
+    final_stage = dvc.run(
+        deps=["derived1"], outs=["final"], cmd="echo final > final"
+    )
+
+    args = ["pipeline", "show", "--outs", "--dot", final_stage.path]
+    with tmp_dir.chdir():
+        command = CmdPipelineShow(args)
+        # Need to test __build_graph directly
+        nodes, edges, is_tree = command._CmdPipelineShow__build_graph(
+            final_stage.path, commands=False, outs=True
+        )
+
+    assert set(nodes) == set(["final", "derived1", "base"])
+    assert edges == [("final", "derived1"), ("derived1", "base")]
+    assert is_tree is True
+
+
 def test_print_locked_stages(tmp_dir, dvc, caplog):
     tmp_dir.dvc_gen({"foo": "foo content", "bar": "bar content"})
     dvc.lock_stage("foo.dvc")