Merge branch 'develop' into issues/1081

7 files changed, 111 insertions, 12 deletions

diff --git a/isort/api.py b/isort/api.py
index 49c693ae..0ea7187f 100644
--- a/isort/api.py
+++ b/isort/api.py
@@ -321,9 +321,11 @@ def sort_imports(
                     output_stream.write(line)
                     indent = ""
 
-                contains_imports = False
                 if next_import_section:
                     cimports = not cimports
+                    contains_imports = True
+                else:
+                    contains_imports = False
                 import_section = next_import_section
                 next_import_section = ""
             else:
diff --git a/isort/main.py b/isort/main.py
index dc2a4280..0bbf3353 100644
--- a/isort/main.py
+++ b/isort/main.py
@@ -4,6 +4,7 @@ import functools
 import glob
 import os
 import re
+import stat
 import sys
 from pathlib import Path
 from typing import Any, Dict, Iterable, Iterator, List, Optional, Sequence
@@ -45,6 +46,12 @@ def is_python_file(path: str) -> bool:
         return False
 
     try:
+        if stat.S_ISFIFO(os.stat(path).st_mode):
+            return False
+    except OSError:
+        pass
+
+    try:
         with open(path, "rb") as fp:
             line = fp.readline(100)
     except OSError:
@@ -416,6 +423,13 @@ def parse_args(argv: Optional[Sequence[str]] = None) -> Dict[str, Any]:
         help="Forces all from imports to appear on their own line",
     )
     parser.add_argument(
+        "--nsl",
+        "--single-line-exclusions",
+        help="One or more modules to exclude from the single line rule.",
+        dest="single_line_exclusions",
+        action="append",
+    )
+    parser.add_argument(
         "--sp",
         "--settings-path",
         dest="settings_path",
diff --git a/isort/output.py b/isort/output.py
index d6a5f562..e9a6f8bf 100644
--- a/isort/output.py
+++ b/isort/output.py
@@ -1,14 +1,15 @@
 import copy
 import itertools
 from functools import partial
-from typing import Iterable, List
-
+from typing import Iterable, List, Tuple
 from isort.format import format_simplified
 
 from . import parse, sorting, wrap
 from .comments import add_to_line as with_comments
 from .settings import DEFAULT_CONFIG, Config
 
+STATEMENT_DECLERATIONS: Tuple[str, ...] = ("def ", "cdef ", "cpdef ", "class ", "@", "async def")
+
 
 def sorted_imports(
     parsed: parse.ParsedContent,
@@ -202,12 +203,7 @@ def sorted_imports(
 
         if config.lines_after_imports != -1:
             formatted_output[imports_tail:0] = ["" for line in range(config.lines_after_imports)]
-        elif extension != "pyi" and (
-            next_construct.startswith("def ")
-            or next_construct.startswith("class ")
-            or next_construct.startswith("@")
-            or next_construct.startswith("async def")
-        ):
+        elif extension != "pyi" and next_construct.startswith(STATEMENT_DECLERATIONS):
             formatted_output[imports_tail:0] = ["", ""]
         else:
             formatted_output[imports_tail:0] = [""]
@@ -242,7 +238,9 @@ def _with_from_imports(
 
         import_start = f"from {module} {import_type} "
         from_imports = list(parsed.imports[section]["from"][module])
-        if not config.no_inline_sort or config.force_single_line:
+        if not config.no_inline_sort or (
+            config.force_single_line and module not in config.single_line_exclusions
+        ):
             from_imports = sorting.naturally(
                 from_imports,
                 key=lambda key: sorting.module_key(
@@ -291,7 +289,7 @@ def _with_from_imports(
                     config,
                 )
                 from_imports = []
-            elif config.force_single_line:
+            elif config.force_single_line and module not in config.single_line_exclusions:
                 import_statement = ""
                 while from_imports:
                     from_import = from_imports.pop(0)
diff --git a/isort/profiles.py b/isort/profiles.py
index 1210c8ef..910da935 100644
--- a/isort/profiles.py
+++ b/isort/profiles.py
@@ -15,7 +15,12 @@ django = {
     "line_length": 79,
 }
 pycharm = {"multi_line_output": 3, "force_grid_wrap": 2}
-google = {"force_single_line": True, "force_sort_within_sections": True, "lexicographical": True}
+google = {
+    "force_single_line": True,
+    "force_sort_within_sections": True,
+    "lexicographical": True,
+    "single_line_exclusions": ("typing",),
+}
 open_stack = {
     "force_single_line": True,
     "force_sort_within_sections": True,
diff --git a/isort/settings.py b/isort/settings.py
index 1885eef3..e05560dd 100644
--- a/isort/settings.py
+++ b/isort/settings.py
@@ -135,6 +135,7 @@ class _Config:
     remove_imports: FrozenSet[str] = frozenset()
     reverse_relative: bool = False
     force_single_line: bool = False
+    single_line_exclusions: Tuple[str, ...] = ()
     default_section: str = "FIRSTPARTY"
     import_headings: Dict[str, str] = field(default_factory=dict)
     balanced_wrapping: bool = False
diff --git a/tests/test_isort.py b/tests/test_isort.py
index 11a7079f..efff42c4 100644
--- a/tests/test_isort.py
+++ b/tests/test_isort.py
@@ -4627,6 +4627,44 @@ IF CEF_VERSION == 3:
     SortImports(file_contents=test_input).output == expected_output
 
 
+def test_cdef_support():
+    assert (
+        SortImports(
+            file_contents="""
+from cpython.version cimport PY_MAJOR_VERSION
+
+cdef extern from *:
+    ctypedef CefString ConstCefString "const CefString"
+"""
+        ).output
+        == """
+from cpython.version cimport PY_MAJOR_VERSION
+
+
+cdef extern from *:
+    ctypedef CefString ConstCefString "const CefString"
+"""
+    )
+
+    assert (
+        SortImports(
+            file_contents="""
+from cpython.version cimport PY_MAJOR_VERSION
+
+cpdef extern from *:
+    ctypedef CefString ConstCefString "const CefString"
+"""
+        ).output
+        == """
+from cpython.version cimport PY_MAJOR_VERSION
+
+
+cpdef extern from *:
+    ctypedef CefString ConstCefString "const CefString"
+"""
+    )
+
+
 def test_top_level_import_order() -> None:
     test_input = (
         "from rest_framework import throttling, viewsets\n"
@@ -4664,3 +4702,23 @@ from flask_security.signals import user_confirmed  # noqa
 from flask_security.signals import user_registered  # noqa
 """
     assert SortImports(file_contents=test_input).output == expected_output
+
+
+def test_single_line_exclusions():
+    test_input = """
+# start comment
+from os import path, system
+from typing import List, TypeVar
+"""
+    expected_output = """
+# start comment
+from os import path
+from os import system
+from typing import List, TypeVar
+"""
+    assert (
+        SortImports(
+            file_contents=test_input, force_single_line=True, single_line_exclusions=("typing",)
+        ).output
+        == expected_output
+    )
diff --git a/tests/test_main.py b/tests/test_main.py
new file mode 100644
index 00000000..300108a0
--- /dev/null
+++ b/tests/test_main.py
@@ -0,0 +1,21 @@
+import os
+import sys
+
+import pytest
+
+from isort import main
+
+
+def test_is_python_file():
+    assert main.is_python_file("file.py")
+    assert main.is_python_file("file.pyi")
+    assert main.is_python_file("file.pyx")
+    assert not main.is_python_file("file.pyc")
+    assert not main.is_python_file("file.txt")
+
+
+@pytest.mark.skipif(sys.platform == "win32", reason="cannot create fifo file on Windows platform")
+def test_is_python_file_fifo(tmpdir):
+    fifo_file = os.path.join(tmpdir, "fifo_file")
+    os.mkfifo(fifo_file)
+    assert not main.is_python_file(fifo_file)