Added test for nested directory.

Author: samdeane

Sources/SwiftFormat/Core/IgnoreFile.swift

@@ -60,6 +60,11 @@ public class IgnoreFile {
   /// Returns nil if no ignore file is found.
   /// Throws an error if an invalid ignore file is found somewhere 
   /// in the directory tree.
+  ///
+  /// Note that we start the search from the given URL's **container**,
+  /// not the URL itself; the URL passed in is expected to be for a file.
+  /// If you pass a directory URL, the search will not include the contents
+  /// of that directory.
   public convenience init?(for url: URL) throws {
       var containingDirectory = url.absoluteURL.standardized
       repeat {

Tests/SwiftFormatTests/Core/IgnoreFileTests.swift

@@ -7,24 +7,35 @@ final class IgnoreFileTests: XCTestCase {
     let url = Bundle.module.url(forResource: "missing", withExtension: "", subdirectory: "Ignore Files")
     XCTAssertNotNil(url)
     XCTAssertNil(try IgnoreFile(forDirectory: url!))
+    XCTAssertNil(try IgnoreFile(for: url!.appending(path:"file.swift")))
   }
 
   func testValidIgnoreFile() throws {
     let url = Bundle.module.url(forResource: "valid", withExtension: "", subdirectory: "Ignore Files")
     XCTAssertNotNil(url)
     XCTAssertNotNil(try IgnoreFile(forDirectory: url!))
+    XCTAssertNotNil(try IgnoreFile(for: url!.appending(path:"file.swift")))
   }
 
   func testInvalidIgnoreFile() throws {
     let url = Bundle.module.url(forResource: "invalid", withExtension: "", subdirectory: "Ignore Files")
     XCTAssertNotNil(url)
     XCTAssertThrowsError(try IgnoreFile(forDirectory: url!))
+    XCTAssertThrowsError(try IgnoreFile(for: url!.appending(path:"file.swift")))
   }
 
   func testEmptyIgnoreFile() throws {
     let url = Bundle.module.url(forResource: "empty", withExtension: "", subdirectory: "Ignore Files")
     XCTAssertNotNil(url)
     XCTAssertThrowsError(try IgnoreFile(forDirectory: url!))
+    XCTAssertThrowsError(try IgnoreFile(for: url!.appending(path:"file.swift")))
+  }
+
+  func testNestedIgnoreFile() throws {
+    let url = Bundle.module.url(forResource: "nested", withExtension: "", subdirectory: "Ignore Files")
+    XCTAssertNotNil(url)
+    let subdirectory = url!.appendingPathComponent("subdirectory").appending(path: "file.swift")
+    XCTAssertNotNil(try IgnoreFile(for: subdirectory))
   }
 
 }

Tests/SwiftFormatTests/Resources/Ignore Files/nested/.swift-format-ignore

@@ -0,0 +1 @@
+*