[wip] unit tests

- re-added redundant `tests` submodules for good form

src/test_util/mock_ids.rs

@@ -109,6 +109,11 @@ impl From<bool> for FileID {
     }
 }
 
+// technically redundant, but kept for refactoring purposes
+#[cfg(test)]
+mod tests {
+    use super::*;
+
     #[test]
     fn true_makes_valids() {
         let uri = Uri::from(true);
@@ -174,3 +179,4 @@ fn false_makes_invalids() {
         test_check((&share_id_i, &file_id), is_share_id_i);
         test_check((&share_id, &file_id_i), is_file_id_i);
     }
+}

src/test_util/mod.rs

@@ -29,8 +29,14 @@ pub fn create_file(data: &[u8]) -> NamedTempFile {
     tmp
 }
 
+// technically redundant, but kept for refactoring purposes
+#[cfg(test)]
+mod tests {
+    use super::*;
+
     #[test]
     #[should_panic = "`impl foo for bar` expected: 1, actual: 0"]
     fn make_check_trait_panic() {
         check_trait(0, 1, "foo", "bar");
     }
+}