A single leading space should not override an otherwise 100% tab-indented file

jvm/CHANGELOG.md

@@ -11,6 +11,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- A single leading space (such as in the copyright header) should not override an otherwise 100% tab-indented file. ([#506](https://github.com/diffplug/selfie/issues/506))
 
 ## [2.4.1] - 2024-10-07
 ### Fixed

jvm/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/guts/EscapeLeadingWhitespace.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2024 DiffPlug
+ * Copyright (C) 2024-2025 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,7 +35,7 @@ internal enum class EscapeLeadingWhitespace {
               .lineSequence()
               .mapNotNull { line ->
                 val whitespace = line.takeWhile { it.isWhitespace() }
-                if (whitespace.isEmpty()) null
+                if (whitespace.isEmpty() || whitespace == " ") null
                 else if (whitespace.all { it == ' ' }) ' '
                 else if (whitespace.all { it == '\t' }) '\t' else MIXED
               }

jvm/selfie-lib/src/commonTest/kotlin/com/diffplug/selfie/guts/EscapeLeadingWhitespaceTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2024 DiffPlug
+ * Copyright (C) 2024-2025 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,16 +29,28 @@ class EscapeLeadingWhitespaceTest {
     appropriateFor("abc\nabc") shouldBe ALWAYS
 
     // all spaces -> only tabs need escape
-    appropriateFor(" ") shouldBe ONLY_ON_TAB
+    appropriateFor(" ") shouldBe ALWAYS
     appropriateFor("  ") shouldBe ONLY_ON_TAB
-    appropriateFor(" \n ") shouldBe ONLY_ON_TAB
+    appropriateFor("  \n  ") shouldBe ONLY_ON_TAB
 
     // all tabs -> only space needs escape
     appropriateFor("\t") shouldBe ONLY_ON_SPACE
     appropriateFor("\t\t") shouldBe ONLY_ON_SPACE
     appropriateFor("\t\n\t") shouldBe ONLY_ON_SPACE
 
     // it's a mess -> everything needs escape
-    appropriateFor("\t\n ") shouldBe ALWAYS
+    appropriateFor("\t\n  ") shouldBe ALWAYS
+
+    // single spaces and tabs -> only tabs need escape
+    appropriateFor(
+        """
+/*
+${' '}* Copyright
+${' '}*/
+interface Foo {
+${'\t'}fun bar()
+}
+""") shouldBe
+        ONLY_ON_SPACE
   }
 }

python/CHANGELOG.md

@@ -2,18 +2,16 @@
 
 Changelog for the selfie Python libraries.
 
-- [`com.diffplug.selfie:selfie-lib:VERSION`](https://pypi.org/project/selfie-lib/)
-- [`com.diffplug.selfie:selfie-runner-pytest:VERSION`](https://pypi.org/project/pytest-selfie/)
-  The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
-  and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+- [`selfie-lib:VERSION`](https://pypi.org/project/selfie-lib/)
+- [`pytest-selfie:VERSION`](https://pypi.org/project/pytest-selfie/)
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+Allowable headings are `Added`, `Fixed`, and `Changed`.
 
 ## [Unreleased]
-### Added
-- TODO
 ### Fixed
-- TODO
-### Changed
-- TODO
+- A single leading space (such as in the copyright header) should not override an otherwise 100% tab-indented file. ([#506](https://github.com/diffplug/selfie/issues/506))
 
 ## [1.0.0] - 2024-12-16
 

python/selfie-lib/selfie_lib/EscapeLeadingWhitespace.py

@@ -33,8 +33,8 @@ def appropriate_for(cls, file_content: str) -> "EscapeLeadingWhitespace":
         common_whitespace = None
 
         for line in file_content.splitlines():
-            whitespace = "".join(c for c in line if c.isspace())
-            if not whitespace:
+            whitespace = line[0 : len(line) - len(line.lstrip())]
+            if whitespace == "" or whitespace == " ":
                 continue
             elif all(c == " " for c in whitespace):
                 whitespace = " "

python/selfie-lib/selfie_lib/__init__.py

@@ -6,6 +6,7 @@
 from .CacheSelfie import cache_selfie_binary as cache_selfie_binary
 from .CacheSelfie import cache_selfie_json as cache_selfie_json
 from .CommentTracker import CommentTracker as CommentTracker
+from .EscapeLeadingWhitespace import EscapeLeadingWhitespace as EscapeLeadingWhitespace
 from .FS import FS as FS
 from .Lens import Camera as Camera
 from .Lens import CompoundLens as CompoundLens

python/selfie-lib/tests/EscapeLeadingWhitespace_test.py

@@ -0,0 +1,59 @@
+from selfie_lib import EscapeLeadingWhitespace
+
+
+def test_detection():
+    # not enough to detect
+    assert EscapeLeadingWhitespace.appropriate_for("") == EscapeLeadingWhitespace.ALWAYS
+    assert (
+        EscapeLeadingWhitespace.appropriate_for("abc") == EscapeLeadingWhitespace.ALWAYS
+    )
+    assert (
+        EscapeLeadingWhitespace.appropriate_for("abc\nabc")
+        == EscapeLeadingWhitespace.ALWAYS
+    )
+
+    # all spaces -> only tabs need escape
+    assert (
+        EscapeLeadingWhitespace.appropriate_for(" ") == EscapeLeadingWhitespace.ALWAYS
+    )
+    assert (
+        EscapeLeadingWhitespace.appropriate_for("  ")
+        == EscapeLeadingWhitespace.ONLY_ON_TAB
+    )
+    assert (
+        EscapeLeadingWhitespace.appropriate_for("  \n  ")
+        == EscapeLeadingWhitespace.ONLY_ON_TAB
+    )
+
+    # all tabs -> only space needs escape
+    assert (
+        EscapeLeadingWhitespace.appropriate_for("\t")
+        == EscapeLeadingWhitespace.ONLY_ON_SPACE
+    )
+    assert (
+        EscapeLeadingWhitespace.appropriate_for("\t\t")
+        == EscapeLeadingWhitespace.ONLY_ON_SPACE
+    )
+    assert (
+        EscapeLeadingWhitespace.appropriate_for("\t\n\t")
+        == EscapeLeadingWhitespace.ONLY_ON_SPACE
+    )
+
+    # it's a mess -> everything needs escape
+    assert (
+        EscapeLeadingWhitespace.appropriate_for("\t\n  ")
+        == EscapeLeadingWhitespace.ALWAYS
+    )
+
+    # single spaces and tabs -> only tabs need escape
+    tab = "\t"
+    test_string = f"""/*
+ * Copyright
+ */
+interface Foo [
+{tab}bar()
+]"""
+    assert (
+        EscapeLeadingWhitespace.appropriate_for(test_string)
+        == EscapeLeadingWhitespace.ONLY_ON_SPACE
+    )