rename testToJsonString and add new test for @Transient serialization

lynglib/src/commonTest/kotlin/OOTest.kt

@@ -887,7 +887,7 @@ class OOTest {
         """.trimIndent())
     }
     @Test
-    fun testToJsonString() = runTest {
+    fun testToStringWithTransient() = runTest {
         eval("""
             class C(amount,@Transient transient=0) {
                 val l by lazy { transient + amount }
@@ -903,4 +903,12 @@ class OOTest {
             println(C(1).lock().lock().amount)
         """.trimIndent())
     }
+
+    @Test
+    fun testToJsonString() = runTest {
+        eval("""
+            class T(a,b,@Transient c=0)
+            assertEquals("{\"a\":\"foo\",\"b\":\"bar\"}",T("foo", "bar").toJsonString())
+        """.trimIndent())
+    }
 }