Refactor code to make it simpler

No change in functionality except the error that is displayed when the
source file does not exist is a little diffferent.

pytest_datafiles.py

@@ -6,6 +6,31 @@
 import pytest
 
 
+def _copy(src, target):
+    if not src.exists():
+        raise ValueError("'%s' does not exist!" % src)
+    if src.isdir():
+        src.copy(target / src.basename)
+    else:  # file
+        src.copy(target)
+
+
+def _copy_all(entry_list, target_dir, on_duplicate):
+    for entry in entry_list:
+        target_entry = target_dir / entry.basename
+        if not target_entry.exists() or on_duplicate == 'overwrite':
+            _copy(entry, target_dir)
+        elif on_duplicate == 'exception':
+            raise ValueError(
+                "'%s' already exists (src %s)" % (
+                    target_entry,
+                    entry,
+                    )
+                )
+        else:  # ignore
+            continue
+
+
 def _is_str(obj):
     """
     Check if 'obj' is a string (both Python 2 and 3)
@@ -16,48 +41,30 @@ def _is_str(obj):
         return isinstance(obj, str)
 
 
-def _copy_file(target_dir, entry, on_duplicate):
-    basename = entry.basename
-    if on_duplicate == 'overwrite' or not (target_dir / basename).exists():
-        entry.copy(target_dir)
-    elif on_duplicate == 'exception':
-        raise ValueError(
-            "'%s' already exists (entry %s)" % (basename, entry)
-            )
-    else:
-        # on_duplicate == 'ignore': do nothing with entry
-        pass
+def _to_py_path(entry_list):
+    converted = []
+    for entry in entry_list:
+        if _is_str(entry):
+            converted.append(path.local(entry))
+        else:
+            converted.append(entry)
+    return converted
+
 
+def _get_all_entries(entry_list, keep_top_dir):
+    all_files = []
+
+    entry_list = _to_py_path(entry_list)
 
-def _copy_dir(target_dir, entry, on_duplicate, keep_top_dir):
-    basename = entry.basename
     if keep_top_dir:
-        if on_duplicate == 'overwrite' or not (target_dir / basename).exists():
-            entry.copy(target_dir / basename)
-        elif on_duplicate == 'exception':
-            raise ValueError(
-                "'%s' already exists (entry %s)" % (basename, entry)
-                )
-        # else: on_duplicate == 'ignore': do nothing with entry
+        all_files = entry_list
     else:
-        # Regular directory (no keep_top_dir). Need to check every file
-        # for duplicates
-        if on_duplicate == 'overwrite':
-            entry.copy(target_dir)
-            return
-        for sub_entry in entry.listdir():
-            if not (target_dir / sub_entry.basename).exists():
-                sub_entry.copy(target_dir / sub_entry.basename)
-                continue
-            if on_duplicate == 'exception':
-                # target exists
-                raise ValueError(
-                    "'%s' already exists (entry %s)" % (
-                        (target_dir / sub_entry.basename),
-                        sub_entry,
-                        )
-                    )
-            # on_duplicate == 'ignore': do nothing with e2
+        for entry in entry_list:
+            if entry.isdir():
+                all_files.extend(entry.listdir())
+            else:
+                all_files.append(entry)
+    return all_files
 
 
 @pytest.fixture
@@ -66,35 +73,24 @@ def datafiles(request, tmpdir):
     pytest fixture to define a 'tmpdir' containing files or directories
     specified with a 'datafiles' mark.
     """
-    content = []
+    entry_list = []
     options = {
         'keep_top_dir': False,
         'on_duplicate': 'exception',  # ignore, overwrite
         }
     for mark in request.node.iter_markers('datafiles'):
-        content.extend(mark.args)
+        entry_list.extend(mark.args)
         options.update(mark.kwargs)
+
     on_duplicate = options['on_duplicate']
     keep_top_dir = options['keep_top_dir']
 
-    if not content:
-        return tmpdir
-
     if keep_top_dir not in (True, False):
         raise ValueError("'keep_top_dir' must be True or False")
     if on_duplicate not in ('exception', 'ignore', 'overwrite'):
         raise ValueError("'on_duplicate' must be 'exception', 'ignore' or "
                          "'overwrite'")
-    for entry in content:
-        if _is_str(entry):
-            entry = path.local(entry)
-        if entry.isfile():
-            _copy_file(tmpdir, entry, on_duplicate)
-        elif entry.isdir():
-            _copy_dir(tmpdir, entry, on_duplicate, keep_top_dir)
-        else:
-            raise ValueError(
-                "entry '%s' is neither file nor dir. Possibly it doesn't "
-                "exist." % entry
-                )
+
+    all_entries = _get_all_entries(entry_list, keep_top_dir)
+    _copy_all(all_entries, tmpdir, on_duplicate)
     return tmpdir

tests/test_pytest_datafiles.py

@@ -323,7 +323,7 @@ def test_ode(datafiles):
     '''.format(FIXTURE_DIR))
     result = testdir.runpytest('-s')
     result.stdout.fnmatch_lines([
-        "E*ValueError:*fileZZ'*is neither file nor dir.*",
+        "E*ValueError:*fileZZ'*does not exist!*",
         ])