Fixed #953: Added support for deduping headings.

CHANGELOG.md

@@ -3,10 +3,11 @@ Changelog
 
 NOTE: isort follows the [semver](https://semver.org/) versioning standard.
 
-### 5.3.0 TBD
+### 5.3.0 Aug 4, 2020
   - Implemented ability to treat all or select comments as code (issue #1357)
   - Implemented ability to use different configs for different file extensions (issue #1162)
   - Implemented ability to specify the types of imports (issue #1181)
+  - Implemented ability to dedup import headings (issue #953)
   - Added experimental support for sorting literals (issue #1358)
   - Added experimental support for sorting and deduping groupings of assignments.
   - Improved handling of deprecated single line variables for usage with Visual Studio Code (issue #1363)

isort/main.py

@@ -673,6 +673,13 @@ def _build_arg_parser() -> argparse.ArgumentParser:
         action="append",
         help="Specifies what extensions isort can never be ran against.",
     )
+    parser.add_argument(
+        "--dedup-headings",
+        dest="dedup_headings",
+        action="store_true",
+        help="Tells isort to only show an identical custom import heading comment once, even if"
+        " there are multiple sections with the comment set.",
+    )
 
     # deprecated options
     parser.add_argument(

isort/output.py

@@ -1,7 +1,7 @@
 import copy
 import itertools
 from functools import partial
-from typing import Iterable, List, Tuple
+from typing import Iterable, List, Set, Tuple
 
 from isort.format import format_simplified
 
@@ -46,6 +46,7 @@ def sorted_imports(
         sections = base_sections + ("no_sections",)
 
     output: List[str] = []
+    seen_headings: Set[str] = set()
     pending_lines_before = False
     for section in sections:
         straight_modules = parsed.imports[section]["straight"]
@@ -152,7 +153,9 @@ def sorted_imports(
                 continue
 
             section_title = config.import_headings.get(section_name.lower(), "")
-            if section_title:
+            if section_title and section_title not in seen_headings:
+                if config.dedup_headings:
+                    seen_headings.add(section_title)
                 section_comment = f"# {section_title}"
                 if section_comment not in parsed.lines_without_imports[0:1]:
                     section_output.insert(0, section_comment)

isort/settings.py

@@ -186,6 +186,7 @@ class _Config:
     constants: FrozenSet[str] = frozenset()
     classes: FrozenSet[str] = frozenset()
     variables: FrozenSet[str] = frozenset()
+    dedup_headings: bool = False
 
     def __post_init__(self):
         py_version = self.py_version

tests/test_ticketed_features.py

@@ -1,6 +1,7 @@
 """A growing set of tests designed to ensure when isort implements a feature described in a ticket
 it fully works as defined in the associated ticket.
 """
+from functools import partial
 from io import StringIO
 
 import pytest
@@ -507,3 +508,38 @@ def test_isort_allows_setting_import_types_issue_1181():
         )
         == "from x import Big, variable, AA\n"
     )
+
+
+def test_isort_enables_deduping_section_headers_issue_953():
+    """isort should provide a way to only have identical import headings show up once.
+    See: https://github.com/timothycrosley/isort/issues/953
+    """
+    isort_code = partial(
+        isort.code,
+        config=Config(
+            import_heading_firstparty="Local imports.",
+            import_heading_localfolder="Local imports.",
+            dedup_headings=True,
+            known_first_party=["isort"],
+        ),
+    )
+
+    assert (
+        isort_code("from . import something")
+        == """# Local imports.
+from . import something
+"""
+    )
+    assert (
+        isort_code(
+            """from isort import y
+
+from . import something"""
+        )
+        == """# Local imports.
+from isort import y
+
+from . import something
+"""
+    )
+    assert isort_code("import os") == "import os\n"