seq: Add tests for default float formats

Add tests for some of the default float formats (%f, %g, %E), mostly
to check that the default precision is correctly set to 6 digits.

Author: drinkcat

tests/by-util/test_seq.rs

@@ -708,6 +708,30 @@ fn test_format_option() {
         .stdout_only("0.00\n0.10\n0.20\n0.30\n0.40\n0.50\n");
 }
 
+#[test]
+fn test_format_option_default_precision() {
+    new_ucmd!()
+        .args(&["-f", "%f", "0", "0.7", "2"])
+        .succeeds()
+        .stdout_only("0.000000\n0.700000\n1.400000\n");
+}
+
+#[test]
+fn test_format_option_default_precision_short() {
+    new_ucmd!()
+        .args(&["-f", "%g", "0", "0.987654321", "2"])
+        .succeeds()
+        .stdout_only("0\n0.987654\n1.97531\n");
+}
+
+#[test]
+fn test_format_option_default_precision_scientific() {
+    new_ucmd!()
+        .args(&["-f", "%E", "0", "0.7", "2"])
+        .succeeds()
+        .stdout_only("0.000000E+00\n7.000000E-01\n1.400000E+00\n");
+}
+
 #[test]
 #[ignore = "Need issue #2660 to be fixed"]
 fn test_auto_precision() {