add tests and docs

Author: madsodgaard

Sources/JExtractSwiftLib/Swift2JavaTranslator.swift

@@ -40,7 +40,7 @@ public final class Swift2JavaTranslator {
   var inputs: [Input] = []
 
   /// A list of used Swift class names that live in dependencies
-  var dependenciesClasses: [String] = []
+  package var dependenciesClasses: [String] = []
 
   // ==== Output state
 

Sources/SwiftJavaDocumentation/Documentation.docc/SupportedFeatures.md

@@ -65,6 +65,8 @@ SwiftJava's `swift-java jextract` tool automates generating Java bindings from S
 | Protocols: `protocol`, existential parameters `any Collection`                       | ❌        | ❌   |
 | Optional types: `Int?`, `AnyObject?`                                                 | ❌        | ❌   |
 | Primitive types: `Bool`, `Int`, `Int8`, `Int16`, `Int32`, `Int64`, `Float`, `Double` | ✅        | ✅   |
+| Parameters: JavaKit wrapped types `JavaLong`, `JavaInteger`                          | ❌        | ✅   |
+| Return values: JavaKit wrapped types `JavaLong`, `JavaInteger`                       | ❌        | ❌   |
 | Unsigned primitive types: `UInt`, `UInt8`, `UInt16`, `UInt32`, `UInt64`              | ❌        | ❌   |
 | String (with copying data)                                                           | ✅        | ✅   |
 | Variadic parameters: `T...`                                                          | ❌        | ❌   |

Tests/JExtractSwiftTests/Asserts/TextAssertions.swift

@@ -29,6 +29,7 @@ func assertOutput(
   _ renderKind: RenderKind,
   swiftModuleName: String = "SwiftModule",
   detectChunkByInitialLines _detectChunkByInitialLines: Int = 4,
+  javaClassLookupTable: [String: String] = [:],
   expectedChunks: [String],
   fileID: String = #fileID,
   filePath: String = #filePath,
@@ -38,6 +39,7 @@ func assertOutput(
   var config = Configuration()
   config.swiftModule = swiftModuleName
   let translator = Swift2JavaTranslator(config: config)
+  translator.dependenciesClasses = Array(javaClassLookupTable.keys)
 
   try! translator.analyze(file: "/fake/Fake.swiftinterface", text: input)
 
@@ -64,7 +66,8 @@ func assertOutput(
       translator: translator,
       javaPackage: "com.example.swift",
       swiftOutputDirectory: "/fake",
-      javaOutputDirectory: "/fake"
+      javaOutputDirectory: "/fake",
+      javaClassLookupTable: javaClassLookupTable
     )
 
     switch renderKind {

Tests/JExtractSwiftTests/JNI/JNIJavaKitTests.swift

@@ -0,0 +1,74 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import JExtractSwiftLib
+import Testing
+
+@Suite
+struct JNIJavaKitTests {
+  let source =
+    """
+    public func function(javaLong: JavaLong, javaInteger: JavaInteger, int: Int64) {}
+    """
+
+  let classLookupTable = [
+    "JavaLong": "java.lang.Long",
+    "JavaInteger": "java.lang.Integer"
+  ]
+
+  @Test
+  func function_javaBindings() throws {
+    try assertOutput(
+      input: source,
+      .jni,
+      .java,
+      javaClassLookupTable: classLookupTable,
+      expectedChunks: [
+      """
+      /**
+      * Downcall to Swift:
+      * {@snippet lang=swift :
+      * public func function(javaLong: JavaLong, javaInteger: JavaInteger, int: Int64)
+      * }
+      */
+      public static void function(java.lang.Long javaLong, java.lang.Integer javaInteger, long int) {
+        SwiftModule.$function(javaLong, javaInteger, int);
+      }
+      """,
+      """
+      private static native void $function(java.lang.Long javaLong, java.lang.Integer javaInteger, long int);
+      """
+      ]
+    )
+  }
+
+  @Test
+  func function_swiftThunks() throws {
+    try assertOutput(
+      input: source,
+      .jni,
+      .swift,
+      detectChunkByInitialLines: 1,
+      javaClassLookupTable: classLookupTable,
+      expectedChunks: [
+        """
+        @_cdecl("Java_com_example_swift_SwiftModule__00024function__Ljava_lang_Long_2Ljava_lang_Integer_2J")
+        func Java_com_example_swift_SwiftModule__00024function__Ljava_lang_Long_2Ljava_lang_Integer_2J(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, javaLong: jobject, javaInteger: jobject, int: jlong) {
+          SwiftModule.function(javaLong: JavaLong(javaThis: javaLong, environment: environment!), javaInteger: JavaInteger(javaThis: javaInteger, environment: environment!), int: Int64(fromJNI: int, in: environment!))
+        }
+        """
+      ]
+    )
+  }
+}