diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index ba6e6a5..941368c 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -2,7 +2,7 @@ name: main
 
 on:
   push:
-    branches: [main]
+    branches: [master]
   pull_request:
 
 jobs:
@@ -22,3 +22,32 @@ jobs:
 
       - name: Lint with flake8
         run: flake8 --count
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+          cache: 'pip'
+  
+      - name: Install pacakge
+        run: |
+          sudo apt-get install -y ffmpeg
+          python -m pip install --upgrade pip
+          pip install -e .
+    
+      - name: Test with pytest
+        run: |
+          pip install -r requirements-test.txt
+          pytest --cov=frequenpy --cov-report=term-missing
+
+      - name: Upload coverage reports to Codecov
+        uses: codecov/codecov-action@v3
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
\ No newline at end of file
diff --git a/README.md b/README.md
index 80d2a8c..d46f43c 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,8 @@
 
 # FrequenPy
 
+![coverage_badge](https://codecov.io/gh/tomaslink/frequenpy/branch/master/graph/badge.svg) 
+
 _FrequenPy_ is a high-precision physics engine dedicated to the study of standing waves and visualization of its normal modes.
 
 This package has educational purposes. 
diff --git a/frequenpy/loaded_string/animation.py b/frequenpy/loaded_string/animation.py
index 1061764..fa75085 100644
--- a/frequenpy/loaded_string/animation.py
+++ b/frequenpy/loaded_string/animation.py
@@ -1,6 +1,7 @@
 import logging
 from os import path, makedirs
 
+import matplotlib
 from matplotlib import pyplot as plt
 from matplotlib import animation
 
@@ -8,6 +9,7 @@
 
 logger = logging.getLogger(__name__)
 
+
 LINE_WIDTH = 1
 LINE_MARKERTYPE = 'o'
 LINE_MARKERSIZE = 8
@@ -120,7 +122,8 @@ def _build_figure(self):
         ax.add_line(self._right_support(support_distance_from_origin))
         ax.add_line(self._line)
 
-        plt.get_current_fig_manager().window.resizable(False, False)
+        if matplotlib.get_backend() == 'TkAgg':
+            plt.get_current_fig_manager().window.resizable(False, False)
 
         return fig
 
diff --git a/requirements-test.txt b/requirements-test.txt
new file mode 100644
index 0000000..be2e3e7
--- /dev/null
+++ b/requirements-test.txt
@@ -0,0 +1 @@
+pytest-cov<5
diff --git a/requirements.txt b/requirements.txt
index 7023c43..a219cd1 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
 flake8<7
-pytest-cov<5
+-r requirements-test.txt
 
 -e .
diff --git a/setup.py b/setup.py
index 9420506..ed9d146 100644
--- a/setup.py
+++ b/setup.py
@@ -25,6 +25,7 @@
     },
     install_requires=[
         'numpy<2',
-        'matplotlib<4'
+        'matplotlib<4',
+        'ffmpeg-python'
     ]
 )
diff --git a/tests/loaded_string/test_animation.py b/tests/loaded_string/test_animation.py
index a4b601c..de24654 100644
--- a/tests/loaded_string/test_animation.py
+++ b/tests/loaded_string/test_animation.py
@@ -1,5 +1,4 @@
 import os
-
 from matplotlib import pyplot
 
 from frequenpy.loaded_string.animation import LoadedStringAnimation