diff --git a/coverage-report.pdf b/coverage-report.pdf
new file mode 100644
index 0000000..0178f02
Binary files /dev/null and b/coverage-report.pdf differ
diff --git a/diffusion2d.py b/diffusion2d.py
index 51a07f2..de69c7b 100644
--- a/diffusion2d.py
+++ b/diffusion2d.py
@@ -38,6 +38,12 @@ def __init__(self):
         self.dt = None
 
     def initialize_domain(self, w=10., h=10., dx=0.1, dy=0.1):
+        # assertion: float check
+        assert isinstance(w, float), "w should be a float"
+        assert isinstance(h, float), "h should be a float"
+        assert isinstance(dx, float), "dx should be a float"
+        assert isinstance(dy, float), "dy should be a float"
+
         self.w = w
         self.h = h
         self.dx = dx
@@ -45,7 +51,12 @@ 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.):
+        # assertion: float check
+        assert isinstance(d, float), "d should be a float"
+        assert isinstance(T_cold, float), "T_cold should be a float"
+        assert isinstance(T_hot, float), "T_hot should be a 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..8f87fb4
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,4 @@
+numpy
+matplotlib
+pytest
+coverage
\ No newline at end of file
diff --git a/tests/integration/test_diffusion2d.py b/tests/integration/test_diffusion2d.py
index fd026b4..9ca132f 100644
--- a/tests/integration/test_diffusion2d.py
+++ b/tests/integration/test_diffusion2d.py
@@ -3,7 +3,8 @@
 """
 
 from diffusion2d import SolveDiffusion2D
-
+import pytest
+import numpy as np
 
 def test_initialize_physical_parameters():
     """
@@ -11,9 +12,46 @@ def test_initialize_physical_parameters():
     """
     solver = SolveDiffusion2D()
 
+    w = 20.
+    h = 10.
+    dx = 0.5
+    dy = 0.2
+    d = 5.
+
+    solver.initialize_domain(w=w, h=h, dx=dx, dy=dy)
+    solver.initialize_physical_parameters(d=d, T_cold=200., T_hot=800.)
+
+    expected_dt = (dx ** 2 * dy ** 2) / (2 * d * (dx ** 2 + dy ** 2))
+    assert solver.dt == pytest.approx(expected_dt)
 
 def test_set_initial_condition():
     """
     Checks function SolveDiffusion2D.get_initial_function
     """
     solver = SolveDiffusion2D()
+
+    w = 20.
+    h = 10.
+    dx = 0.5
+    dy = 0.2
+    d = 5.
+    T_cold = 200.
+    T_hot = 800.
+    r, cx, cy = 2, 5, 5
+    r2 = r ** 2
+    nx = int(w / dx)
+    ny = int(h / dy)
+
+    solver.initialize_domain(w=w, h=h, dx=dx, dy=dy)
+    solver.initialize_physical_parameters(d=d, T_cold=T_cold, T_hot=T_hot)
+
+    u_actual = solver.set_initial_condition()
+    u_expected = T_cold * np.ones((nx, ny))
+
+    for i in range(nx):
+        for j in range(ny):
+            p2 = (i * dx - cx) ** 2 + (j * dy - cy) ** 2
+            if p2 < r2:
+                u_expected[i, j] = T_hot
+
+    assert np.allclose(u_actual, u_expected), "Integration test failed with set_initial_condition."
\ No newline at end of file
diff --git a/tests/unit/test_diffusion2d_functions.py b/tests/unit/test_diffusion2d_functions.py
index c4277ff..faab7dd 100644
--- a/tests/unit/test_diffusion2d_functions.py
+++ b/tests/unit/test_diffusion2d_functions.py
@@ -3,7 +3,8 @@
 """
 
 from diffusion2d import SolveDiffusion2D
-
+import pytest
+import numpy as np
 
 def test_initialize_domain():
     """
@@ -11,16 +12,72 @@ def test_initialize_domain():
     """
     solver = SolveDiffusion2D()
 
+    w = 20.
+    h = 10.
+    dx = 0.5
+    dy = 0.2
+
+    expected_nx = int(w / dx)
+    expected_ny = int(h / dy)
+
+    solver.initialize_domain(w=w, h=h, dx=dx, dy=dy)
+
+    assert solver.nx == expected_nx
+    assert solver.ny == expected_ny
 
 def test_initialize_physical_parameters():
     """
-    Checks function SolveDiffusion2D.initialize_domain
+    Checks function SolveDiffusion2D.initialize_physical_parameters
     """
     solver = SolveDiffusion2D()
 
+    d = 5.
+    T_cold = 200.
+    T_hot = 800.
+    dx = 0.2
+    dy = 0.1
+
+    solver.dx = dx
+    solver.dy = dy
+    dx2 = dx * dx
+    dy2 = dy * dy
+    expected_dt = dx2 * dy2 / (2 * d * (dx2 + dy2))
+
+    solver.initialize_physical_parameters(d=d, T_cold=T_cold, T_hot=T_hot)
+
+    assert solver.dt == pytest.approx(expected_dt)
 
 def test_set_initial_condition():
     """
-    Checks function SolveDiffusion2D.get_initial_function
+    Checks function SolveDiffusion2D.set_initial_condition
     """
     solver = SolveDiffusion2D()
+
+    w = 20.
+    h = 10.
+    dx = 0.5
+    dy = 0.2
+    T_cold = 200.
+    T_hot = 800.
+    r, cx, cy = 2, 5, 5
+    r2 = r ** 2
+
+    solver.w = w
+    solver.h = h
+    solver.dx = dx
+    solver.dy = dy
+    solver.T_cold = T_cold
+    solver.T_hot = T_hot
+    solver.nx = int(w / dx)
+    solver.ny = int(h / dy)
+
+    u_actual = solver.set_initial_condition()
+    u_expected = solver.T_cold * np.ones((solver.nx, solver.ny))
+
+    for i in range(solver.nx):
+        for j in range(solver.ny):
+            p2 = (i * solver.dx - cx) ** 2 + (j * solver.dy - cy) ** 2
+            if p2 < r2:
+                u_expected[i, j] = solver.T_hot
+
+    assert np.allclose(u_actual, u_expected), "Unit test failed with set_initial_condition."
\ No newline at end of file
diff --git a/tox.toml b/tox.toml
new file mode 100644
index 0000000..5bf687d
--- /dev/null
+++ b/tox.toml
@@ -0,0 +1,11 @@
+[tox]
+env_list = ["test_env"]
+no_package = true
+
+[testenv]
+deps = ["-rrequirements.txt"]
+
+commands = [
+    ["coverage", "run", "-m", "pytest"],
+    ["coverage", "report", "-m"]
+]
\ No newline at end of file