Changed encoded float::Inf as null in json

DEVELOPMENT.md

@@ -11,6 +11,15 @@ The crate comes with additional submodules to aid with testing, to ensure you ha
 git clone --recurse-submodules https://github.com/jorgecarleitao/arrow2
 ```
 
+## Checks
+
+PRs will run the following checks:
+
+```bash
+cargo fmt --all -- --check
+cargo clippy --all --features=full --tests -- -D warnings
+```
+
 ## Testing
 
 The simplest way to test the crate is to run 

src/io/json/write/serialize.rs

@@ -56,7 +56,7 @@ where
         array.iter(),
         |x, buf| {
             if let Some(x) = x {
-                if T::is_nan(*x) {
+                if T::is_nan(*x) || T::is_infinite(*x) {
                     buf.extend(b"null")
                 } else {
                     lexical_to_bytes_mut(*x, buf)

tests/it/io/json/write.rs

@@ -28,18 +28,34 @@ fn int32() -> Result<()> {
 
 #[test]
 fn f32() -> Result<()> {
-    let array = Float32Array::from([Some(1.5), Some(2.5), Some(f32::NAN), None, Some(5.5)]);
+    let array = Float32Array::from([
+        Some(1.5),
+        Some(2.5),
+        Some(f32::NAN),
+        Some(f32::INFINITY),
+        Some(f32::NEG_INFINITY),
+        None,
+        Some(5.5),
+    ]);
 
-    let expected = r#"[1.5,2.5,null,null,5.5]"#;
+    let expected = r#"[1.5,2.5,null,null,null,null,5.5]"#;
 
     test!(array, expected)
 }
 
 #[test]
 fn f64() -> Result<()> {
-    let array = Float64Array::from([Some(1.5), Some(2.5), Some(f64::NAN), None, Some(5.5)]);
+    let array = Float64Array::from([
+        Some(1.5),
+        Some(2.5),
+        Some(f64::NAN),
+        Some(f64::INFINITY),
+        Some(f64::NEG_INFINITY),
+        None,
+        Some(5.5),
+    ]);
 
-    let expected = r#"[1.5,2.5,null,null,5.5]"#;
+    let expected = r#"[1.5,2.5,null,null,null,null,5.5]"#;
 
     test!(array, expected)
 }