added deserialiser tests, fixed some bugs in deserialised

tests/deserialise/int.zig

@@ -0,0 +1,38 @@
+const std = @import("std");
+
+pub const msgpack = @import("msgpack");
+
+const deserialise = msgpack.deserialise.deserialise;
+
+fn test_int(bytes: []const u8, expected: i64) !void {
+    const alloc = std.testing.allocator;
+
+    const obj = try deserialise(alloc, bytes);
+    defer obj.deinit(alloc);
+
+    try std.testing.expectEqual(expected, obj.integer);
+}
+
+test "int i8" {
+    try test_int(&[_]u8{ 0xd0, 0x80 }, std.math.minInt(i8));
+
+    try test_int(&[_]u8{0x7f}, std.math.maxInt(i8));
+}
+
+test "int i16" {
+    try test_int(&[_]u8{ 0xd1, 0x80, 0x00 }, std.math.minInt(i16));
+
+    try test_int(&[_]u8{ 0xcd, 0x7f, 0xff }, std.math.maxInt(i16));
+}
+
+test "int i32" {
+    try test_int(&[_]u8{ 0xd2, 0x80, 0x00, 0x00, 0x00 }, std.math.minInt(i32));
+
+    try test_int(&[_]u8{ 0xce, 0x7f, 0xff, 0xff, 0xff }, std.math.maxInt(i32));
+}
+
+test "int i64" {
+    try test_int(&[_]u8{ 0xd3, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, std.math.minInt(i64));
+
+    try test_int(&[_]u8{ 0xcf, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }, std.math.maxInt(i64));
+}