diff --git a/src/parser.rs b/src/parser.rs
index ad4f23d..381fb10 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -147,4 +147,44 @@ pub mod parser {
             return parsed
         }
     }
+
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        #[test]
+        fn removing_text() {
+            let sometext: String = String::from("a1234567890");
+            let numberparser = NumberParser { filepath: String::from("")};
+            let removetext = numberparser.remove_some_data(&sometext);
+            let mut result = true;
+
+            for i in 0..removetext.len() {
+                let c = removetext.chars().nth(i).unwrap();
+
+                if !c.is_numeric() {
+                    result = false;
+                    break;
+                }
+            }
+
+            assert_eq!(result, true);
+        }
+
+        #[test]
+        fn adding_prefix() {
+            let sometext: String = String::from("1234567890");
+            let numberparser = NumberParser { filepath: String::from("")};
+            let modified = numberparser.add_prefix(sometext);
+
+            let chars = modified.chars().clone();
+            let firstcharcheck: char = chars.clone().nth(0).unwrap();
+            let secondcharcheck: char = chars.clone().nth(1).unwrap();
+
+            assert_eq!(firstcharcheck, '+');
+            assert_eq!(secondcharcheck, '1');
+        }
+    }
 }
+