fixes to nuon for inf, -inf, and NaN (#5818)

crates/nu-command/src/formats/to/nuon.rs

@@ -87,7 +87,11 @@ fn value_to_string(v: &Value, span: Span) -> Result<String, ShellError> {
         )),
         Value::Filesize { val, .. } => Ok(format!("{}b", *val)),
         Value::Float { val, .. } => {
-            if &val.round() == val {
+            if &val.round() == val
+                && val != &f64::NAN
+                && val != &f64::INFINITY
+                && val != &f64::NEG_INFINITY
+            {
                 Ok(format!("{}.0", *val))
             } else {
                 Ok(format!("{}", *val))

crates/nu-command/tests/format_conversions/nuon.rs

@@ -202,3 +202,39 @@ fn float_doesnt_become_int() {
 
     assert_eq!(actual.out, "1.0")
 }
+
+#[test]
+fn float_inf_parsed_properly() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            inf | to nuon
+        "#
+    ));
+
+    assert_eq!(actual.out, "inf")
+}
+
+#[test]
+fn float_neg_inf_parsed_properly() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            -inf | to nuon
+        "#
+    ));
+
+    assert_eq!(actual.out, "-inf")
+}
+
+#[test]
+fn float_nan_parsed_properly() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            NaN | to nuon
+        "#
+    ));
+
+    assert_eq!(actual.out, "NaN")
+}