Expose the :core file helpers an app that syncs needs; align foldCase

core/src/main/kotlin/io/github/maxdac/marknotes/core/notes/CaseFolding.kt

@@ -7,8 +7,10 @@ package io.github.maxdac.marknotes.core.notes
  * The apps that sync notes compute the same key in the shared sync library (`foldCase`); both must agree, because
  * a rename is "case only" exactly when the keys are equal. This version has no dependency on that library and
  * folds through the JVM's simple case mappings (upper, then lower), which gives the same equivalence classes as the
- * `C` and `S` mappings of CaseFolding.txt except for the dotted and dotless I, kept apart below. The sync
- * library's own test vectors are repeated in `CaseFoldingTest`.
+ * `C` and `S` mappings of CaseFolding.txt except for the dotted and dotless I, kept apart below, and the three
+ * `S` mappings of Unicode 15.1 that older JVMs lack, added below. The keys themselves may differ from the library's
+ * (it folds Cherokee to upper case): only the classes must agree. The sync library's own test vectors are repeated
+ * in `CaseFoldingTest`.
  */
 fun foldCase(path: String): String {
     val folded = StringBuilder(path.length)
@@ -18,6 +20,14 @@ fun foldCase(path: String): String {
         index += Character.charCount(codePoint)
         val key = when (codePoint) {
             DOTTED_CAPITAL_I, DOTLESS_SMALL_I -> codePoint
+
+            // Simple foldings added in Unicode 15.1 that the JVM's upper-then-lower mapping lacks.
+            GREEK_SMALL_IOTA_DIALYTIKA_PERISPOMENI -> GREEK_SMALL_IOTA_DIALYTIKA_TONOS
+
+            GREEK_SMALL_UPSILON_DIALYTIKA_PERISPOMENI -> GREEK_SMALL_UPSILON_DIALYTIKA_TONOS
+
+            LONG_S_T_LIGATURE -> ST_LIGATURE
+
             else -> Character.toLowerCase(Character.toUpperCase(codePoint))
         }
         folded.appendCodePoint(key)
@@ -27,3 +37,9 @@ fun foldCase(path: String): String {
 
 private const val DOTTED_CAPITAL_I = 0x0130
 private const val DOTLESS_SMALL_I = 0x0131
+private const val GREEK_SMALL_IOTA_DIALYTIKA_PERISPOMENI = 0x1FD3
+private const val GREEK_SMALL_IOTA_DIALYTIKA_TONOS = 0x0390
+private const val GREEK_SMALL_UPSILON_DIALYTIKA_PERISPOMENI = 0x1FE3
+private const val GREEK_SMALL_UPSILON_DIALYTIKA_TONOS = 0x03B0
+private const val LONG_S_T_LIGATURE = 0xFB05
+private const val ST_LIGATURE = 0xFB06

core/src/main/kotlin/io/github/maxdac/marknotes/core/notes/CaseRename.kt

@@ -18,8 +18,12 @@ internal fun fileIdentity(file: File): String =
     Files.readAttributes(file.toPath(), BasicFileAttributes::class.java).fileKey()?.toString()
         ?: if (windows) WindowsFiles.identity(file) else throw IOException("Cannot verify file identity: $file")
 
-/** Never use Java moves here: Unix implementations may check existence then perform a replacing rename. */
-internal fun renameCaseFile(source: File, target: File) {
+/**
+ * Renames [source] to [target] without ever replacing an existing file, then checks that the exact case of the new
+ * name and the file identity survived. Never use Java moves here: Unix implementations may check existence then
+ * perform a replacing rename. Public for apps that keep their own files next to the notes (the sync base copies).
+ */
+fun renameCaseFile(source: File, target: File) {
     val identity = fileIdentity(source)
     moveFileNoReplace(source, target)
     val names = target.parentFile.list().orEmpty().toList()

core/src/main/kotlin/io/github/maxdac/marknotes/core/notes/NewFile.kt

@@ -7,10 +7,11 @@ import java.nio.file.Files
 import java.nio.file.StandardOpenOption
 import java.nio.file.attribute.FileTime
 
-internal enum class NewFileStage { BYTES_WRITTEN, MTIME_SET, FLUSHED, PUBLISHED }
+/** The steps of [writeNewFile], reported to its `checkpoint` so tests can interrupt it after each one. */
+enum class NewFileStage { BYTES_WRITTEN, MTIME_SET, FLUSHED, PUBLISHED }
 
 /** Only complete, timestamped, flushed bytes may become visible at the create-only destination. */
-internal fun writeNewFile(
+fun writeNewFile(
     target: File,
     bytes: ByteArray,
     modifiedMillis: Long,

core/src/test/kotlin/io/github/maxdac/marknotes/core/notes/CaseFoldingTest.kt

@@ -11,6 +11,14 @@ class CaseFoldingTest {
         assertEquals(foldCase("ſ/Σ.md"), foldCase("S/ς.md"))
     }
 
+    @Test
+    fun foldingsAddedInUnicode151JoinTheirTargets() {
+        // The JVM's upper-then-lower mapping lacks these; the shared sync library folds them.
+        assertEquals(foldCase("\u0390.md"), foldCase("\u1FD3.md"))
+        assertEquals(foldCase("\u03B0.md"), foldCase("\u1FE3.md"))
+        assertEquals(foldCase("\uFB06.md"), foldCase("\uFB05.md"))
+    }
+
     @Test
     fun dottedAndDotlessIAreNotFoldedToI() {
         assertNotEquals(foldCase("İ.md"), foldCase("i.md"))