test: printf: Add nan, inf, negative zero

Add a few end-to-end tests for printf of unusual floats (nan,
infinity, negative zero).

tests/by-util/test_printf.rs

@@ -886,6 +886,30 @@ fn float_with_zero_precision_should_pad() {
         .stdout_only("-01");
 }
 
+#[test]
+fn float_non_finite() {
+    new_ucmd!()
+        .args(&[
+            "%f %f %F %f %f %F",
+            "nan",
+            "-nan",
+            "nan",
+            "inf",
+            "-inf",
+            "inf",
+        ])
+        .succeeds()
+        .stdout_only("nan -nan NAN inf -inf INF");
+}
+
+#[test]
+fn float_zero_neg_zero() {
+    new_ucmd!()
+        .args(&["%f %f", "0.0", "-0.0"])
+        .succeeds()
+        .stdout_only("0.000000 -0.000000");
+}
+
 #[test]
 fn precision_check() {
     new_ucmd!()