diff --git a/requirements.txt b/requirements.txt
index 2b076d0..db9c234 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,11 @@
 certifi==2023.7.22
 charset-normalizer==3.3.2
+coverage==7.3.2
 idna==3.4
+iniconfig==2.0.0
 maturin==1.3.1
+packaging==23.2
+pluggy==1.3.0
+pytest==7.4.3
 requests==2.31.0
 urllib3==2.0.7
diff --git a/src/lib.rs b/src/lib.rs
index d3cf904..4974904 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,6 @@
 use pyo3::prelude::*;
 use std::time::Instant;
+use pyo3::exceptions::PyException;
 
 #[pyclass]
 #[derive(Clone)]
@@ -19,6 +20,7 @@ struct Init {
     time: Instant,
     #[pyo3(get)]
     results: Results,
+    status: bool,
 }
 
 #[pymethods]
@@ -34,21 +36,28 @@ impl Init {
         Init {
             time: Instant::now(),
             results: res,
+            status: false,
         }
     }
 
     fn tic(&mut self) {
-        self.time = Instant::now()
+        self.time = Instant::now();
+        self.status = true;
     }
 
-    fn toc(&mut self) {
-        let elapsed_time = self.time.elapsed();
-        self.results = Results {
-            nanos: elapsed_time.as_nanos(),
-            micros: elapsed_time.as_micros(),
-            millis: elapsed_time.as_millis(),
-            seconds: elapsed_time.as_secs_f64(),
-        };
+    fn toc(&mut self) -> PyResult<()> {
+        if self.status == false {
+            Err(PyException::new_err("tic() must be called before toc()"))    
+        } else {       
+            let elapsed_time = self.time.elapsed();
+            self.results = Results {
+                nanos: elapsed_time.as_nanos(),
+                micros: elapsed_time.as_micros(),
+                millis: elapsed_time.as_millis(),
+                seconds: elapsed_time.as_secs_f64(),
+            };
+            Ok(())
+        }
     }
 }
 
@@ -57,3 +66,27 @@ fn tictoc(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<Init>()?;
     Ok(())
 }
+
+#[test]
+fn test_new() {
+    let init = Init::new();
+    assert_eq!(init.results.nanos,0);
+}
+
+#[test]
+fn test_tic() {
+    let mut init = Init::new();
+    let time1 = init.time;
+    init.tic();
+    let time2 = init.time;
+    assert!(time2 > time1)
+}
+
+#[test]
+fn test_toc() {
+    let mut init = Init::new();
+    init.tic();
+    println!("{}","test");
+    let _ = init.toc();
+    assert!(init.results.nanos > 0)
+}