Cleanup. Began unit_test.rs

hw5/task1/src/child/mod.rs

     match count {
         Ok(value) => {
 
-            if value > 0 { }
-            fork_children(0, value - 1, start_pid);
+            if value > 0 {
+                fork_children(0, value - 1, start_pid);
+            } else {
+                return Err("Number of forks must not be zero.".to_string())
+            }
+
             Ok(())
         },
         Err(_) => {

hw5/task1/src/unit_tests.rs

 #[cfg(test)]
 mod tests {
+
+    use procinfo;
     use child::*;
 
+    #[test]
     fn test_zero_forks(){
-        assert_eq!(run_childs(123,"2"))
+        assert_eq!(run_childs(123,"0"), Err("Number of forks must not be zero.".to_string()))
+    }
+
+    #[test]
+    fn test_one_fork(){
+        assert_eq!(run_childs(procinfo::pid::stat_self().unwrap().pid,"1"), Ok(()))
+    }
+
+    #[test]
+    fn test_wrong_pid(){
+        assert_eq!(run_childs(2,"1"), Ok(()))
     }
 }