Fix an issue that led to a crash, if an empty array was decoded (#52)

Thanks @calebkleveter for reporting this

Author: fabianfett

Sources/PureSwiftJSON/Decoding/JSONUnkeyedDecodingContainer.swift

@@ -5,13 +5,15 @@ struct JSONUnkeyedDecodingContainer: UnkeyedDecodingContainer {
     let array: [JSONValue]
 
     let count: Int? // protocol requirement to be optional
-    var isAtEnd = false
+    var isAtEnd: Bool
     var currentIndex = 0
 
     init(impl: JSONDecoderImpl, codingPath: [CodingKey], array: [JSONValue]) {
         self.impl = impl
         self.codingPath = codingPath
         self.array = array
+
+        isAtEnd = array.count == 0
         count = array.count
     }
 

Tests/PureSwiftJSONTests/Decoding/JSONDecoderTests.swift

@@ -111,4 +111,32 @@ class JSONDecoderTests: XCTestCase {
             XCTAssertNotNil(context.underlyingError)
         }
     }
+
+    func testDecodeEmptyArray() {
+        let json = """
+        {
+            "array": []
+        }
+        """
+        struct Foo: Decodable {
+            let array: [String]
+        }
+        let decoder = PSJSONDecoder()
+
+        var result: Foo?
+        XCTAssertNoThrow(result = try decoder.decode(Foo.self, from: json.utf8))
+        XCTAssertEqual(result?.array, [])
+    }
+
+    func testIfUserInfoIsHandedDown() {
+        let json = "{}"
+        struct Foo: Decodable {
+            init(decoder: Decoder) {
+                XCTAssertEqual(decoder.userInfo as? [CodingUserInfoKey: String], [CodingUserInfoKey(rawValue: "foo")!: "bar"])
+            }
+        }
+        var decoder = PSJSONDecoder()
+        decoder.userInfo[CodingUserInfoKey(rawValue: "foo")!] = "bar"
+        XCTAssertNoThrow(_ = try decoder.decode(Foo.self, from: json.utf8))
+    }
 }

Tests/PureSwiftJSONTests/Encoding/JSONEncoderTests.swift

@@ -132,4 +132,15 @@ class JSONEncoderTests: XCTestCase {
         XCTAssertNoThrow(parsed = try JSONParser().parse(bytes: XCTUnwrap(result)))
         XCTAssertEqual(parsed, .object(["sub": .object(["key": .string("sub"), "value": .number("12")])]))
     }
+
+    func testIfUserInfoIsHandedDown() {
+        struct Foo: Encodable {
+            func encode(to encoder: Encoder) throws {
+                XCTAssertEqual(encoder.userInfo as? [CodingUserInfoKey: String], [CodingUserInfoKey(rawValue: "foo")!: "bar"])
+            }
+        }
+        var encoder = PSJSONEncoder()
+        encoder.userInfo[CodingUserInfoKey(rawValue: "foo")!] = "bar"
+        XCTAssertNoThrow(_ = try encoder.encode(Foo()))
+    }
 }