Add is_exec_found to utils and use it in dagascii module

dvc/dagascii.py

@@ -7,7 +7,6 @@
 import os
 import pydoc
 import sys
-from distutils.spawn import find_executable
 
 from grandalf.graphs import Edge
 from grandalf.graphs import Graph
@@ -16,7 +15,7 @@
 from grandalf.routing import EdgeViewer
 from grandalf.routing import route_with_lines
 
-from dvc.utils import boxify
+from dvc.utils import boxify, is_exec_found
 
 
 logger = logging.getLogger(__name__)
@@ -39,8 +38,7 @@
 
 def find_pager(pager_cmd, pager_cmd_with_format, pager_env_name):
     if sys.stdout.isatty():
-        less_found = find_executable(pager_cmd) is not None
-        if less_found:
+        if is_exec_found(pager_cmd):
             pager_cmd = os.getenv(pager_env_name, pager_cmd_with_format)
 
             def less_pager(text):

dvc/utils/__init__.py

@@ -420,3 +420,8 @@ def resolve_output(inp, out):
     if os.path.isdir(out):
         return os.path.join(out, name)
     return out
+
+
+def is_exec_found(exec_name):
+    cmd = '({}) 2>/dev/null'.format(exec_name)
+    return hasattr(os, 'system') and os.system(cmd) == 0

tests/func/test_utils.py

@@ -88,3 +88,13 @@ def test_makedirs_permissions(tmpdir):
 
     assert stat.S_IMODE(os.stat(test_dir).st_mode) == dir_mode
     assert stat.S_IMODE(os.stat(intermediate_dir).st_mode) == dir_mode
+
+
+def test_is_exec_found_returns_true_when_program_exists():
+    result = utils.is_exec_found("python")
+    assert result == True
+
+
+def test_is_exec_found_returns_false_when_program_is_missing():
+    result = utils.is_exec_found("some-missing-program")
+    assert result == False