add tests for invalid precision check

Author: Kev1n8

src/uucore/src/lib/features/format/mod.rs

@@ -92,11 +92,7 @@ impl Display for FormatError {
                 "format '{}' has no % directive",
                 String::from_utf8_lossy(s)
             ),
-            Self::InvalidPrecision(precision) => write!(
-                f,
-                "invalid precision: '{}'",
-                precision
-            ),
+            Self::InvalidPrecision(precision) => write!(f, "invalid precision: '{}'", precision),
             // TODO: Error message below needs some work
             Self::WrongSpecType => write!(f, "wrong % directive type was given"),
             Self::IoError(_) => write!(f, "io error"),

tests/by-util/test_printf.rs

@@ -774,3 +774,21 @@ fn format_spec_zero_string_fails() {
     // It is invalid to have the format spec '%0s'
     new_ucmd!().args(&["%0s", "3"]).fails().code_is(1);
 }
+
+#[test]
+fn invalid_precision_fails() {
+    // It is invalid to have length of output string greater than i32::MAX
+    new_ucmd!()
+        .args(&["%.*d", "2147483648", "0"])
+        .fails()
+        .stderr_is("printf: invalid precision: '2147483648'\n");
+}
+
+#[test]
+fn float_invalid_precision_fails() {
+    // It is invalid to have length of output string greater than i32::MAX
+    new_ucmd!()
+        .args(&["%.*f", "9999999999", "0"])
+        .fails()
+        .stderr_is("printf: invalid precision: '9999999999'\n");
+}