Another attempt at test stabalization.

Source/ParameterEncoder.swift

@@ -61,7 +61,8 @@ open class JSONParameterEncoder: ParameterEncoder {
         return JSONParameterEncoder(encoder: encoder)
     }
 
-    let encoder: JSONEncoder
+    /// `JSONEncoder` used to encode parameters.
+    public let encoder: JSONEncoder
 
     /// Creates an instance with the provided `JSONEncoder`.
     ///

Tests/ParameterEncoderTests.swift

@@ -106,6 +106,10 @@ final class JSONParameterEncoderTests: BaseTestCase {
 
     @available(macOS 10.13, iOS 11.0, tvOS 11.0, watchOS 4.0, *)
     func testTestJSONEncoderSortedKeysHasSortedKeys() throws {
+        // Apparently marking the method as unavailable doesn't prevent it from running on older OSes.
+        guard #available(macOS 10.13, iOS 11.0, tvOS 11.0, watchOS 4.0, *) else {
+            return
+        }
         // Given
         let encoder = JSONParameterEncoder.sortedKeys
         let request = URLRequest.makeHTTPBinRequest()

Tests/ResponseSerializationTests.swift

@@ -156,7 +156,7 @@ class DataResponseSerializationTestCase: BaseTestCase {
         XCTAssertTrue(result.isFailure)
         XCTAssertNil(result.value)
         XCTAssertNotNil(result.error)
-        
+
         if let error = result.error?.asAFError {
             XCTAssertTrue(error.isInputDataNilOrZeroLength)
         } else {
@@ -770,7 +770,7 @@ class DownloadResponseSerializationTestCase: BaseTestCase {
         XCTAssertTrue(result.isFailure)
         XCTAssertNil(result.value)
         XCTAssertNotNil(result.error)
-        
+
         if let error = result.error?.asAFError {
             XCTAssertTrue(error.isInputDataNilOrZeroLength)
         } else {