seq: add tests for infinity and -infinity args

src/uu/seq/src/numberparse.rs

@@ -477,11 +477,23 @@ mod tests {
     #[test]
     fn test_parse_inf() {
         assert_eq!(parse("inf"), Number::Float(ExtendedBigDecimal::Infinity));
+        assert_eq!(
+            parse("infinity"),
+            Number::Float(ExtendedBigDecimal::Infinity)
+        );
         assert_eq!(parse("+inf"), Number::Float(ExtendedBigDecimal::Infinity));
+        assert_eq!(
+            parse("+infinity"),
+            Number::Float(ExtendedBigDecimal::Infinity)
+        );
         assert_eq!(
             parse("-inf"),
             Number::Float(ExtendedBigDecimal::MinusInfinity)
         );
+        assert_eq!(
+            parse("-infinity"),
+            Number::Float(ExtendedBigDecimal::MinusInfinity)
+        );
     }
 
     #[test]

tests/by-util/test_seq.rs

@@ -619,11 +619,21 @@ fn test_neg_inf() {
     run(&["--", "-inf", "0"], b"-inf\n-inf\n-inf\n");
 }
 
+#[test]
+fn test_neg_infinity() {
+    run(&["--", "-infinity", "0"], b"-inf\n-inf\n-inf\n");
+}
+
 #[test]
 fn test_inf() {
     run(&["inf"], b"1\n2\n3\n");
 }
 
+#[test]
+fn test_infinity() {
+    run(&["infinity"], b"1\n2\n3\n");
+}
+
 #[test]
 fn test_inf_width() {
     run(