Support Graphviz installed from Conda

Graphviz installed using Conda is using .bat scripts
to correctly setup running it on Windows.

Author: prmtl

pydot_ng/__init__.py

@@ -398,6 +398,10 @@ def graph_from_incidence_matrix(matrix, node_prefix='', directed=False):
     return graph
 
 
+def is_qouted(path):
+    return path.startswith('"') and path.endswith('"')
+
+
 def __find_executables(path):
     """Used by find_graphviz
 
@@ -409,7 +413,8 @@ def __find_executables(path):
     Otherwise returns None
     """
 
-    success = False
+    any_found = False
+
     progs = {
         "dot": "",
         "twopi": "",
@@ -419,35 +424,35 @@ def __find_executables(path):
         "sfdp": "",
     }
 
-    was_quoted = False
     path = path.strip()
-    if path.startswith('"') and path.endswith('"'):
+    path_template = "{}"
+
+    if is_qouted(path):
         path = path[1:-1]
-        was_quoted = True
+        path_template = "\"{}\""
 
     if not os.path.isdir(path):
         return None
 
+    extensions_priority = (
+        "",  # "unix"
+        ".bat",
+        ".exe",
+    )
+
     for prg in progs:
         if progs[prg]:
             continue
 
-        prg_path = os.path.join(path, prg)
-        prg_exe_path = prg_path + ".exe"
+        for ext in extensions_priority:
+            prg_path = os.path.join(path, prg + ext)
 
-        if os.path.exists(prg_path):
-            if was_quoted:
-                prg_path = "\"{}\"".format(prg_path)
-            progs[prg] = prg_path
-            success = True
-
-        elif os.path.exists(prg_exe_path):
-            if was_quoted:
-                prg_exe_path = "\"{}\"".format(prg_exe_path)
-            progs[prg] = prg_exe_path
-            success = True
+            if os.path.exists(prg_path):
+                any_found = True
+                progs[prg] = path_template.format(prg_path)
+                break
 
-    if success:
+    if any_found:
         return progs
 
     return None

test/test_pydot.py

@@ -303,20 +303,25 @@ def test_find_executables_path_needs_strip(tmpdir):
         ) == sorted(progs)
 
 
-def test_find_executables_unix_and_exe_exists(tmpdir):
+@pytest.mark.parametrize(
+    "more_important,less_important",
+    (("", ".exe"), (".bat", ".exe"), ("", ".bat")),
+    ids=["unix-over-exe", "bar-over-exe", "unix-over-bat"],
+)
+def test_find_executables_priority(more_important, less_important, tmpdir):
     path = str(tmpdir)
-    prog_unix_path = str(tmpdir.join("dot"))
-    prog_exe_path = str(tmpdir.join("dot.exe"))
+    prog_more_imp = str(tmpdir.join("dot" + more_important))
+    prog_less_imp = str(tmpdir.join("dot" + less_important))
 
-    with open(prog_unix_path, "w"):
-        with open(prog_exe_path, "w"):
+    with open(prog_more_imp, "w"):
+        with open(prog_less_imp, "w"):
             progs = pydot.__find_executables(path)
-            assert progs["dot"] == prog_unix_path
-            assert progs["dot"] != prog_exe_path
+            assert progs["dot"] == prog_more_imp
+            assert progs["dot"] != prog_less_imp
 
 
 @pytest.mark.parametrize("quoted", (True, False), ids=("quoted", "unqoted"))
-@pytest.mark.parametrize("extension", ("", ".exe"))
+@pytest.mark.parametrize("extension", ("", ".exe", ".bat"))
 @pytest.mark.parametrize(
     "program", ("dot", "twopi", "neato", "circo", "fdp", "sfdp")
 )
@@ -326,8 +331,8 @@ def test_find_executables(tmpdir, program, extension, quoted):
 
     with open(prog_path, "w"):
         if quoted:
-            path = "\"{}\"".format(path)
-            prog_path = "\"{}\"".format(prog_path)
+            path = '"{}"'.format(path)
+            prog_path = '"{}"'.format(prog_path)
 
         progs = pydot.__find_executables(str(path))
         assert progs[program] == prog_path