Force floats to output a decimal in nuon (#5768)

* Force floats to output a decimal in nuon

* Add test

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

@@ -86,7 +86,13 @@ fn value_to_string(v: &Value, span: Span) -> Result<String, ShellError> {
             span,
         )),
         Value::Filesize { val, .. } => Ok(format!("{}b", *val)),
-        Value::Float { val, .. } => Ok(format!("{}", *val)),
+        Value::Float { val, .. } => {
+            if &val.round() == val {
+                Ok(format!("{}.0", *val))
+            } else {
+                Ok(format!("{}", *val))
+            }
+        }
         Value::Int { val, .. } => Ok(format!("{}", *val)),
         Value::List { vals, .. } => {
             let headers = get_columns(vals);

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

@@ -190,3 +190,15 @@ fn read_bool() {
 
     assert_eq!(actual.out, "true")
 }
+
+#[test]
+fn float_doesnt_become_int() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            1.0 | to nuon
+        "#
+    ));
+
+    assert_eq!(actual.out, "1.0")
+}