diff --git a/tests/calc_test.py b/tests/calc_test.py
new file mode 100644
index 0000000..8867a68
--- /dev/null
+++ b/tests/calc_test.py
@@ -0,0 +1,34 @@
+import pytest
+from main import add, sub, mult, div  # Import functions from main.py
+
+# Test cases for addition
+def test_add():
+    assert add(2, 3) == 5
+    assert add(-1, 1) == 0
+    assert add(0, 0) == 0
+    assert add(1.5, 2.5) == 4.0
+    assert add(-3, -7) == -10
+
+# Test cases for subtraction
+def test_sub():
+    assert sub(5, 3) == 2
+    assert sub(10, 10) == 0
+    assert sub(0, 5) == -5
+    assert sub(3.5, 1.2) == 2.3
+
+# Test cases for multiplication
+def test_mult():
+    assert mult(3, 4) == 12
+    assert mult(0, 100) == 0
+    assert mult(-2, 5) == -10
+    assert mult(1.5, 2) == 3.0
+
+# Test cases for division
+def test_div():
+    assert div(10, 2) == 5
+    assert div(5, 1) == 5
+    assert div(9, 3) == 3
+    assert div(7.5, 2.5) == 3.0
+
+    with pytest.raises(ZeroDivisionError):
+        div(5, 0)