diff --git a/coverage-report.pdf b/coverage-report.pdf
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diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..e9479e1
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,6 @@
+numpy
+matplotlib
+pytest
+coverage
+tox
+
diff --git a/tests/integration/__pycache__/test_diffusion2d.cpython-38-pytest-8.3.5.pyc b/tests/integration/__pycache__/test_diffusion2d.cpython-38-pytest-8.3.5.pyc
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diff --git a/tests/integration/test_diffusion2d.py b/tests/integration/test_diffusion2d.py
index fd026b4..b856704 100644
--- a/tests/integration/test_diffusion2d.py
+++ b/tests/integration/test_diffusion2d.py
@@ -1,19 +1,64 @@
 """
 Tests for functionality checks in class SolveDiffusion2D
 """
+import numpy as np
+import pytest
 
 from diffusion2d import SolveDiffusion2D
 
 
 def test_initialize_physical_parameters():
     """
-    Checks function SolveDiffusion2D.initialize_domain
+    Integration test:
+    initialize_domain + initialize_physical_parameters
+    检查 dt 是否按公式正确计算
     """
     solver = SolveDiffusion2D()
 
+    # 先初始化计算域
+    w, h = 3.0, 2.0
+    dx, dy = 0.5, 0.25
+    solver.initialize_domain(w=w, h=h, dx=dx, dy=dy)
+
+    # 再初始化物理参数
+    d = 4.0
+    T_cold = 300.0
+    T_hot = 700.0
+    solver.initialize_physical_parameters(d=d, T_cold=T_cold, T_hot=T_hot)
+
+    # 手算 dt
+    dx2, dy2 = dx * dx, dy * dy
+    expected_dt = dx2 * dy2 / (2 * d * (dx2 + dy2))
+
+    assert np.isclose(solver.dt, expected_dt)
+
 
 def test_set_initial_condition():
     """
-    Checks function SolveDiffusion2D.get_initial_function
+    Integration test:
+    initialize_domain + initialize_physical_parameters + set_initial_condition
+    检查整个初始温度场 u 是否正确
     """
     solver = SolveDiffusion2D()
+
+    # 完整工作流
+    w, h = 3.0, 2.0
+    dx, dy = 0.5, 0.25
+    solver.initialize_domain(w=w, h=h, dx=dx, dy=dy)
+    solver.initialize_physical_parameters(d=4.0, T_cold=300.0, T_hot=700.0)
+
+    u0 = solver.set_initial_condition()
+
+    # 构造 expected_u（和源码逻辑完全一致）
+    expected_u = solver.T_cold * np.ones((solver.nx, solver.ny), dtype=float)
+
+    r, cx, cy = 2, 5, 5
+    r2 = r ** 2
+    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:
+                expected_u[i, j] = solver.T_hot
+
+    assert np.allclose(u0, expected_u)
+
diff --git a/tests/unit/__pycache__/test_diffusion2d_functions.cpython-38-pytest-8.3.5.pyc b/tests/unit/__pycache__/test_diffusion2d_functions.cpython-38-pytest-8.3.5.pyc
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diff --git a/tests/unit/test_diffusion2d_functions.py b/tests/unit/test_diffusion2d_functions.py
index c4277ff..78f2c8f 100644
--- a/tests/unit/test_diffusion2d_functions.py
+++ b/tests/unit/test_diffusion2d_functions.py
@@ -1,6 +1,8 @@
 """
 Tests for functions in class SolveDiffusion2D
 """
+import numpy as np
+import pytest
 
 from diffusion2d import SolveDiffusion2D
 
@@ -11,16 +13,63 @@ def test_initialize_domain():
     """
     solver = SolveDiffusion2D()
 
+    w, h = 3.0, 2.0
+    dx, dy = 0.5, 0.25
+
+    solver.initialize_domain(w=w, h=h, dx=dx, dy=dy)
+
+    assert solver.w == w
+    assert solver.h == h
+    assert solver.dx == dx
+    assert solver.dy == dy
+
+    assert solver.nx == int(w / dx)
+    assert solver.ny == int(h / dy)
+
 
 def test_initialize_physical_parameters():
     """
-    Checks function SolveDiffusion2D.initialize_domain
+    Checks function SolveDiffusion2D.initialize_physical_parameters
     """
     solver = SolveDiffusion2D()
 
+    solver.dx = 0.5
+    solver.dy = 0.25
+
+    d = 4.0
+    T_cold = 300.0
+    T_hot = 700.0
+
+    solver.initialize_physical_parameters(d=d, T_cold=T_cold, T_hot=T_hot)
+
+    assert solver.D == d
+    assert solver.T_cold == T_cold
+    assert solver.T_hot == T_hot
+
+    dx2, dy2 = solver.dx * solver.dx, solver.dy * solver.dy
+    expected_dt = dx2 * dy2 / (2 * solver.D * (dx2 + dy2))
+    assert np.isclose(solver.dt, expected_dt)
+
 
 def test_set_initial_condition():
     """
-    Checks function SolveDiffusion2D.get_initial_function
+    Checks function SolveDiffusion2D.set_initial_condition
     """
     solver = SolveDiffusion2D()
+
+    solver.nx = 30
+    solver.ny = 20
+    solver.dx = 0.5
+    solver.dy = 0.25
+    solver.T_cold = 300.0
+    solver.T_hot = 700.0
+
+    u0 = solver.set_initial_condition()
+
+    assert isinstance(u0, np.ndarray)
+    assert u0.shape == (solver.nx, solver.ny)
+    assert np.issubdtype(u0.dtype, np.floating)
+
+    assert np.isclose(u0.min(), solver.T_cold)
+    assert np.isclose(u0.max(), solver.T_hot)
+
diff --git a/tox.toml b/tox.toml
new file mode 100644
index 0000000..17539d0
--- /dev/null
+++ b/tox.toml
@@ -0,0 +1,7 @@
+[tox]
+env_list = ["py"]
+
+[testenv]
+deps = ["-rrequirements.txt"]
+commands = [["python", "-m", "pytest"]]
+