From 55b3c47bbfd33b0b059fe9207ffc196cff840981 Mon Sep 17 00:00:00 2001
From: Ruslan Kuprieiev <ruslan@iterative.ai>
Date: Tue, 28 Aug 2018 11:25:28 +0300
Subject: [PATCH] pipeline: process edges and nodes separately

Signed-off-by: Ruslan Kuprieiev <ruslan@iterative.ai>
---
 dvc/command/pipeline.py | 26 ++++++++++++++++----------
 tests/test_pipeline.py  | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 10 deletions(-)

diff --git a/dvc/command/pipeline.py b/dvc/command/pipeline.py
index 4fd75ba6d..280b8be94 100644
--- a/dvc/command/pipeline.py
+++ b/dvc/command/pipeline.py
@@ -38,32 +38,38 @@ class CmdPipelineShow(CmdBase):
         G = pipelines[0]
         stages = networkx.get_node_attributes(G, 'stage')
 
-        nodes = set()
+        nodes = []
+        for n in G.nodes():
+            stage = stages[n]
+            if commands:
+                if stage.cmd is None:
+                    continue
+                nodes.append(stage.cmd)
+            elif outs:
+                for out in stage.outs:
+                    nodes.append(str(out))
+            else:
+                nodes.append(stage.relpath)
+
+        if len(nodes) == 0:
+            return
+
         edges = []
         for e in G.edges():
             from_stage = stages[e[0]]
             to_stage = stages[e[1]]
             if commands:
-                nodes.add(from_stage.cmd)
                 if to_stage.cmd is None:
                     continue
-                nodes.add(to_stage.cmd)
                 edges.append((from_stage.cmd, to_stage.cmd))
             elif outs:
                 for from_out in from_stage.outs:
                     for to_out in to_stage.outs:
-                        nodes.add(str(from_out))
-                        nodes.add(str(to_out))
                         edges.append((str(from_out),
                                       str(to_out)))
             else:
-                nodes.add(from_stage.relpath)
-                nodes.add(to_stage.relpath)
                 edges.append((from_stage.relpath, to_stage.relpath))
 
-        nodes = list(nodes)
-        assert len(nodes) > 0
-
         d = Dagascii(nodes, edges)
         d.draw()
 
diff --git a/tests/test_pipeline.py b/tests/test_pipeline.py
index af5d9ea22..8a6646b03 100644
--- a/tests/test_pipeline.py
+++ b/tests/test_pipeline.py
@@ -1,8 +1,49 @@
 from dvc.main import main
 
+from tests.basic_env import TestDvc
 from tests.test_repro import TestRepro, TestReproChangedDeepData
 
 
+class TestPipelineShowSingle(TestDvc):
+    def setUp(self):
+        super(TestPipelineShowSingle, self).setUp()
+        self.stage = 'foo.dvc'
+        ret = main(['add', self.FOO])
+        self.assertEqual(ret, 0)
+
+    def test(self):
+        ret = main(['pipeline', 'show', self.stage])
+        self.assertEqual(ret, 0)
+
+    def test_commands(self):
+        ret = main(['pipeline', 'show', self.stage, '--commands'])
+        self.assertEqual(ret, 0)        
+
+    def test_outs(self):
+        ret = main(['pipeline', 'show', self.stage, '--outs'])
+        self.assertEqual(ret, 0)        
+
+    def test_ascii(self):
+        ret = main(['pipeline', 'show', '--ascii', self.stage])
+        self.assertEqual(ret, 0)
+
+    def test_ascii_commands(self):
+        ret = main(['pipeline', 'show', '--ascii', self.stage, '--commands'])
+        self.assertEqual(ret, 0)
+
+    def test_ascii_outs(self):
+        ret = main(['pipeline', 'show', '--ascii', self.stage, '--outs'])
+        self.assertEqual(ret, 0)
+
+    def test_not_dvc_file(self):
+        ret = main(['pipeline', 'show', self.FOO])
+        self.assertNotEqual(ret, 0)
+
+    def test_non_existing(self):
+        ret = main(['pipeline', 'show', 'non-existing'])
+        self.assertNotEqual(ret, 0)
+
+
 class TestPipelineShow(TestRepro):
     def test(self):
         ret = main(['pipeline', 'show', self.file1_stage])