Temporarily switch JavaKitTests target to XCTest

Command-line testing on macOS is broken for the JavaKitTests due to an
interaction between the Java Virtual Machine, a helper test process
for swift-testing (`swiftpm-testing-helper`), and some macOS security
features. Work around the issue by replacing our use of swift-testing
with XCTest, whose helper process doesn't seem to have this problem.
Only do so for test targets that need to spin up an instance of the
JVM, and keep using swift-testing everywhere we can.

This makes me very sad, but is better than the current solution of
disabling these tests when running from the terminal. Once we've found
a solution for the underlying issue, we'll revert this change as get
back to swift-testing and its much nicer testing output.

Fixes issue #43 without disabling tests.

Author: DougGregor

Tests/JavaKitTests/BasicRuntimeTests.swift

@@ -15,61 +15,68 @@
 import JavaKit
 import JavaKitNetwork
 import JavaKitVM
-import Testing
+import XCTest // NOTE: Workaround for https://github.com/swiftlang/swift-java/issues/43
 
 @MainActor
 let jvm = try! JavaVirtualMachine(vmOptions: [])
 
-@Suite
 @MainActor
-struct BasicRuntimeTests {
-  @Test("Object management", .disabled(if: isLinux, "Attempts to refcount a null pointer on Linux"))
-  func javaObjectManagement() throws {
+class BasicRuntimeTests: XCTestCase {
+  func testJavaObjectManagement() throws {
+    if isLinux {
+      throw XCTSkip("Attempts to refcount a null pointer on Linux")
+    }
+
     let sneakyJavaThis: jobject
     do {
       let object = JavaObject(environment: jvm.environment)
-      #expect(object.toString().starts(with: "java.lang.Object"))
+      XCTAssert(object.toString().starts(with: "java.lang.Object"))
 
       // Make sure this object was promoted to a global reference.
-      #expect(object.javaEnvironment.pointee?.pointee.GetObjectRefType(object.javaEnvironment, object.javaThis) == JNIGlobalRefType)
+      XCTAssertEqual(object.javaEnvironment.pointee?.pointee.GetObjectRefType(object.javaEnvironment, object.javaThis), JNIGlobalRefType)
 
       // Keep track of the Java object.
       sneakyJavaThis = object.javaThis
     }
 
     // The reference should now be invalid, because we've deleted the
     // global reference.
-    #expect(jvm.environment.pointee?.pointee.GetObjectRefType(jvm.environment, sneakyJavaThis) == JNIInvalidRefType)
+    XCTAssertEqual(jvm.environment.pointee?.pointee.GetObjectRefType(jvm.environment, sneakyJavaThis), JNIInvalidRefType)
 
     // 'super' and 'as' don't require allocating a new holder.
     let url = try URL("http://swift.org", environment: jvm.environment)
     let superURL = url.super
-    #expect(url.javaHolder === superURL.javaHolder)
+    XCTAssert(url.javaHolder === superURL.javaHolder)
     let urlAgain = superURL.as(URL.self)!
-    #expect(url.javaHolder === urlAgain.javaHolder)
+    XCTAssert(url.javaHolder === urlAgain.javaHolder)
   }
 
-  @Test("Java exceptions", .disabled(if: isLinux, "Attempts to refcount a null pointer on Linux"))
-  func javaExceptionsInSwift() throws {
+  func testJavaExceptionsInSwift() throws {
+    if isLinux {
+      throw XCTSkip("Attempts to refcount a null pointer on Linux")
+    }
+
     do {
       _ = try URL("bad url", environment: jvm.environment)
     } catch {
-      #expect(String(describing: error) == "no protocol: bad url")
+      XCTAssert(String(describing: error) == "no protocol: bad url")
     }
   }
 
-  @Test("Static methods", .disabled(if: isMacOS, "Fails on macOS command line"))
-  func staticMethods() throws {
+  func testStaticMethods() throws {
+    if isLinux {
+      throw XCTSkip("Attempts to refcount a null pointer on Linux")
+    }
+
     let urlConnectionClass = try JavaClass<URLConnection>(in: jvm.environment)
-    #expect(urlConnectionClass.getDefaultAllowUserInteraction() == false)
+    XCTAssert(urlConnectionClass.getDefaultAllowUserInteraction() == false)
   }
 
-  @Test("Class instance lookup")
-  func classInstanceLookup() throws {
+  func testClassInstanceLookup() throws {
     do {
       _ = try JavaClass<Nonexistent>(in: jvm.environment)
     } catch {
-      #expect(String(describing: error) == "org/swift/javakit/Nonexistent")
+      XCTAssertEqual(String(describing: error), "org/swift/javakit/Nonexistent")
     }
   }
 }
@@ -85,12 +92,3 @@ var isLinux: Bool {
   return false
   #endif
 }
-
-/// Whether we're running on MacOS.
-var isMacOS: Bool {
-  #if os(macOS)
-  return true
-  #else
-  return false
-  #endif
-}