diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d9739ac
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.venv/
+__pycache__/
+*.ipynb
diff --git a/coverage-report.pdf b/coverage-report.pdf
new file mode 100644
index 0000000..8d3f6c4
Binary files /dev/null and b/coverage-report.pdf differ
diff --git a/diffusion2d.py b/diffusion2d.py
index 51a07f2..2278bae 100644
--- a/diffusion2d.py
+++ b/diffusion2d.py
@@ -38,6 +38,10 @@ def __init__(self):
         self.dt = None
 
     def initialize_domain(self, w=10., h=10., dx=0.1, dy=0.1):
+        assert isinstance(w, float)
+        assert isinstance(h, float)
+        assert isinstance(dx, float)
+        assert isinstance(dy, float)
         self.w = w
         self.h = h
         self.dx = dx
@@ -45,7 +49,10 @@ def initialize_domain(self, w=10., h=10., dx=0.1, dy=0.1):
         self.nx = int(w / dx)
         self.ny = int(h / dy)
 
-    def initialize_physical_parameters(self, d=4., T_cold=300, T_hot=700):
+    def initialize_physical_parameters(self, d=4., T_cold=300., T_hot=700.):
+        assert isinstance(d, float)
+        assert isinstance(T_cold, float)
+        assert isinstance(T_hot, float)
         self.D = d
         self.T_cold = T_cold
         self.T_hot = T_hot
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..a850b08
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,15 @@
+contourpy==1.3.3
+cycler==0.12.1
+fonttools==4.61.1
+iniconfig==2.3.0
+kiwisolver==1.4.9
+matplotlib==3.10.8
+numpy==2.4.1
+packaging==25.0
+pillow==12.1.0
+pluggy==1.6.0
+Pygments==2.19.2
+pyparsing==3.3.1
+pytest==9.0.2
+python-dateutil==2.9.0.post0
+six==1.17.0
diff --git a/tests/integration/test_diffusion2d.py b/tests/integration/test_diffusion2d.py
index fd026b4..1cff2fd 100644
--- a/tests/integration/test_diffusion2d.py
+++ b/tests/integration/test_diffusion2d.py
@@ -2,6 +2,9 @@
 Tests for functionality checks in class SolveDiffusion2D
 """
 
+import numpy
+import pytest
+
 from diffusion2d import SolveDiffusion2D
 
 
@@ -10,6 +13,9 @@ def test_initialize_physical_parameters():
     Checks function SolveDiffusion2D.initialize_domain
     """
     solver = SolveDiffusion2D()
+    solver.initialize_domain(w=20.0, h=20.0, dx=5.0, dy=5.0)
+    solver.initialize_physical_parameters(d=5.0, T_cold=400.0, T_hot=600.0)
+    assert solver.dt == pytest.approx(1.25, rel=1e-6)
 
 
 def test_set_initial_condition():
@@ -17,3 +23,15 @@ def test_set_initial_condition():
     Checks function SolveDiffusion2D.get_initial_function
     """
     solver = SolveDiffusion2D()
+    solver.initialize_domain(w=20.0, h=20.0, dx=2.0, dy=2.0)
+    solver.initialize_physical_parameters(d=5.0, T_cold=400.0, T_hot=600.0)
+    actual_result = solver.set_initial_condition()
+
+    expected_result = 400.0 * numpy.ones((10, 10))
+    for i in range(10):
+        for j in range(10):
+            p2 = (i * 2.0 - 5.0) ** 2 + (j * 2.0 - 5.0) ** 2
+            if p2 < 4:
+                expected_result[i, j] = 600.0
+
+    assert numpy.allclose(actual_result, expected_result)
diff --git a/tests/unit/test_diffusion2d_functions.py b/tests/unit/test_diffusion2d_functions.py
index c4277ff..bd74863 100644
--- a/tests/unit/test_diffusion2d_functions.py
+++ b/tests/unit/test_diffusion2d_functions.py
@@ -2,6 +2,9 @@
 Tests for functions in class SolveDiffusion2D
 """
 
+import numpy
+import pytest
+
 from diffusion2d import SolveDiffusion2D
 
 
@@ -10,6 +13,9 @@ def test_initialize_domain():
     Check function SolveDiffusion2D.initialize_domain
     """
     solver = SolveDiffusion2D()
+    solver.initialize_domain(w=20.0, h=20.0, dx=0.5, dy=0.5)
+    assert solver.nx == 40
+    assert solver.ny == 40
 
 
 def test_initialize_physical_parameters():
@@ -17,6 +23,10 @@ def test_initialize_physical_parameters():
     Checks function SolveDiffusion2D.initialize_domain
     """
     solver = SolveDiffusion2D()
+    solver.dx = 0.5
+    solver.dy = 0.5
+    solver.initialize_physical_parameters(d=3.0, T_cold=200.0, T_hot=800.0)
+    assert solver.dt == pytest.approx(0.02083333333, rel=1e-6)
 
 
 def test_set_initial_condition():
@@ -24,3 +34,52 @@ def test_set_initial_condition():
     Checks function SolveDiffusion2D.get_initial_function
     """
     solver = SolveDiffusion2D()
+    solver.nx = 5
+    solver.ny = 5
+    solver.dx = 3
+    solver.dy = 3
+    solver.T_cold = 200.0
+    solver.T_hot = 800.0
+
+    actual_result = solver.set_initial_condition()
+    expected_result = numpy.array(
+        [
+            [
+                200.0,
+                200.0,
+                200.0,
+                200.0,
+                200.0,
+            ],
+            [
+                200.0,
+                200.0,
+                200.0,
+                200.0,
+                200.0,
+            ],
+            [
+                200.0,
+                200.0,
+                800.0,
+                200.0,
+                200.0,
+            ],
+            [
+                200.0,
+                200.0,
+                200.0,
+                200.0,
+                200.0,
+            ],
+            [
+                200.0,
+                200.0,
+                200.0,
+                200.0,
+                200.0,
+            ],
+        ]
+    )
+
+    assert numpy.array_equal(actual_result, expected_result)
diff --git a/tox.toml b/tox.toml
new file mode 100644
index 0000000..3e2a990
--- /dev/null
+++ b/tox.toml
@@ -0,0 +1,7 @@
+requires = ["tox>=4"]
+env_list = ["pytest_testing"]
+
+[env.pytest_testing]
+description = "Run pytest"
+deps = ["-r requirements.txt"]
+commands = [["python", "-m", "pytest"]]