diff --git a/.github/workflows/python_test.yml b/.github/workflows/python_test.yml
index 93282b2..b9b54a5 100644
--- a/.github/workflows/python_test.yml
+++ b/.github/workflows/python_test.yml
@@ -3,6 +3,8 @@ name: Run Python Tests
 on:
   push:
     branches: [ main ]
+  pull_request:
+    branches: [ main ]
 
 jobs:
   test:
@@ -13,6 +15,10 @@ jobs:
         uses: actions/setup-python@v2
         with:
           python-version: 3.8
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt
       - name: Run tests
         run: |
           python -m unittest test_main.py -v
\ No newline at end of file
diff --git a/main.py b/main.py
index 8d0b480..0d1c2b6 100644
--- a/main.py
+++ b/main.py
@@ -1,3 +1,4 @@
+import numpy
 class Calculator:
     """A simple calculator with basic arithmetic operations."""
 
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..296d654
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1 @@
+numpy
\ No newline at end of file