Fix deleteLastPathComponent() for absolute paths with trailing /

Paths like /home/ would return "" instead of /

Author: rjmansfield

Sources/FoundationEssentials/String/String+Path.swift

@@ -63,7 +63,12 @@ extension String {
             // This is a trailing slash. Ignore it.
             let beforeLastSlash = self[startIndex..<lastSlash].lastIndex { $0 == "/" }
             if let beforeLastSlash {
-                return String(self[startIndex..<beforeLastSlash])
+                if beforeLastSlash == startIndex {
+                    // Only the first slash remains, return a bare slash.
+                    return "/"
+                } else {
+                    return String(self[startIndex..<beforeLastSlash])
+                }
             } else {
                 // No other slash. Return empty string.
                 return ""

Tests/FoundationEssentialsTests/DataIOTests.swift

@@ -255,6 +255,7 @@ class DataIOTests : XCTestCase {
         XCTAssertEqual("/".deletingLastPathComponent(), "/")
         XCTAssertEqual("q".deletingLastPathComponent(), "")
         XCTAssertEqual("/aaa".deletingLastPathComponent(), "/")
+        XCTAssertEqual("/aaa/".deletingLastPathComponent(), "/")
         XCTAssertEqual("/a/b/c/".deletingLastPathComponent(), "/a/b")
         XCTAssertEqual("hello".deletingLastPathComponent(), "")
         XCTAssertEqual("hello/".deletingLastPathComponent(), "")

Tests/FoundationEssentialsTests/FileManager/FileManagerTests.swift

@@ -458,11 +458,7 @@ final class FileManagerTests : XCTestCase {
             XCTAssertEqual(try $0.subpathsOfDirectory(atPath: ".").sorted(), ["dir", "dir/bar", "dir/foo", "dir2", "dir2/bar", "dir2/foo", "other_file"])
             XCTAssertEqual($0.contents(atPath: "dir/foo"), data)
             XCTAssertEqual($0.contents(atPath: "dir2/foo"), data)
-#if os(Windows)
             XCTAssertEqual($0.delegateCaptures.shouldCopy, [.init("dir", "dir2"), .init("dir/bar", "dir2/bar"), .init("dir/foo", "dir2/foo")])
-#else
-            XCTAssertEqual($0.delegateCaptures.shouldCopy, [.init("dir", "dir2"), .init("dir/foo", "dir2/foo"), .init("dir/bar", "dir2/bar")])
-#endif
 
             XCTAssertThrowsError(try $0.copyItem(atPath: "does_not_exist", toPath: "dir3")) {
                 XCTAssertEqual(($0 as? CocoaError)?.code, .fileReadNoSuchFile)