test: record from/to json behavior

json/from_json.mbt

@@ -1,4 +1,4 @@
-// Copyright 2024 International Digital Economy Academy
+// Copyright 2025 International Digital Economy Academy
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

json/from_json_test.mbt

@@ -1,4 +1,4 @@
-// Copyright 2024 International Digital Economy Academy
+// Copyright 2025 International Digital Economy Academy
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -382,3 +382,51 @@ test "jsonvalue" {
     ,
   )
 }
+
+test "int roundtrip" {
+  let u = (123).to_json()
+  let v : Int = @json.from_json!(u)
+  inspect!(v, content="123")
+  let u = (-123).to_json()
+  let v : Int = @json.from_json!(u)
+  inspect!(v, content="-123")
+}
+
+test "uint roundtrip" {
+  let u = 123U.to_json()
+  let v : UInt = @json.from_json!(u)
+  inspect!(v, content="123")
+  let u = 4294967295U.to_json()
+  let v : UInt = @json.from_json!(u)
+  inspect!(v, content="4294967295")
+}
+
+test "uint" {
+  let v : UInt = @json.from_json!(Number(4294967295))
+  inspect!(v, content="4294967295")
+  let v : UInt = @json.from_json!(Number(-1))
+  inspect!(v, content="0")
+  let v : UInt = @json.from_json!(Number(4294967296))
+  inspect!(v, content="4294967295")
+}
+
+test "int64 roundtrip" {
+  let u = 123L.to_json()
+  let v : Int64 = @json.from_json!(u)
+  inspect!(v, content="123")
+  let u = 9223372036854775807L.to_json()
+  let v : Int64 = @json.from_json!(u)
+  inspect!(v, content="9223372036854775807")
+  let u = (-9223372036854775808L).to_json()
+  let v : Int64 = @json.from_json!(u)
+  inspect!(v, content="-9223372036854775808")
+}
+
+test "uint64 roundtrip" {
+  let u = 123UL.to_json()
+  let v : UInt64 = @json.from_json!(u)
+  inspect!(v, content="123")
+  let u = 18446744073709551615UL.to_json()
+  let v : UInt64 = @json.from_json!(u)
+  inspect!(v, content="18446744073709551615")
+}

json/to_json_test.mbt

@@ -1,4 +1,4 @@
-// Copyright 2024 International Digital Economy Academy
+// Copyright 2025 International Digital Economy Academy
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -21,8 +21,44 @@ test "Int::to_json" {
   inspect!((42).to_json(), content="Number(42)")
 }
 
+test "UInt::to_json" {
+  inspect!(42U.to_json(), content="Number(42)")
+}
+
 test "Int64::to_json" {
-  inspect!(42L.to_json(), content="Number(42)")
+  inspect!(
+    42L.to_json(),
+    content=
+      #|String("42")
+    ,
+  )
+  inspect!(
+    (-9223372036854775808L).to_json(),
+    content=
+      #|String("-9223372036854775808")
+    ,
+  )
+  inspect!(
+    9223372036854775807L.to_json(),
+    content=
+      #|String("9223372036854775807")
+    ,
+  )
+}
+
+test "UInt64::to_json" {
+  inspect!(
+    42UL.to_json(),
+    content=
+      #|String("42")
+    ,
+  )
+  inspect!(
+    18446744073709551615UL.to_json(),
+    content=
+      #|String("18446744073709551615")
+    ,
+  )
 }
 
 test "Double::to_json" {