diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
new file mode 100644
index 0000000000..9412b7842d
--- /dev/null
+++ b/.github/workflows/main.yml
@@ -0,0 +1,36 @@
+
+name: Testing
+
+on:
+  push:
+
+jobs:
+  ubuntu_test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.11'
+
+      - name: Run tests
+        run: python -m unittest discover -s . -p "*.py"
+
+  windows_test:
+    runs-on: windows-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.11'
+
+      - name: Run tests
+        run: python -m unittest discover -s . -p "*.py"
diff --git a/circle.py b/circle.py
index c3eb8647c9..796d6d4ad8 100644
--- a/circle.py
+++ b/circle.py
@@ -1,10 +1,69 @@
 import math
-
+import unittest
 
 def area(r):
+    '''
+    Takes circle radius value, returns circle area value
+
+    Example:
+        area(3)
+        28.274333882308138
+    '''
+    if not isinstance(r, int):
+        print("Not integer")
+        return 0
+    if r < 0:
+        print("Negative number")
+        return 0
     return math.pi * r * r
 
 
 def perimeter(r):
+    '''
+    Takes circle radius value, returns circuit value
+
+    Example:
+        perimeter(3)
+        18.84955592153876
+    '''
+    if not isinstance(r, int):
+        print("Not integer")
+        return 0
+    if r < 0:
+        print("Negative number")
+        return 0
     return 2 * math.pi * r
 
+
+class CircleTestCase(unittest.TestCase):
+    def test_zero_area(self):
+        res = area(0)
+        self.assertEqual(res, 0)
+
+    def test_regular_area(self):
+        res = area(10)
+        self.assertEqual(res, 314.1592653589793)
+
+    def test_str_area(self):
+        res = area("a")
+        self.assertEqual(res, 0)
+
+    def test_negative_area(self):
+        res = area(-2)
+        self.assertEqual(res, 0)
+
+    def test_zero_perimeter(self):
+        res = perimeter(0)
+        self.assertEqual(res, 0)
+
+    def test_regular_perimeter(self):
+        res = perimeter(3)
+        self.assertEqual(res, 18.84955592153876)
+
+    def test_str_perimeter(self):
+        res = perimeter("a")
+        self.assertEqual(res, 0)
+
+    def test_negative_perimeter(self):
+        res = perimeter(-2)
+        self.assertEqual(res, 0)
diff --git a/docs/README.md b/docs/README.md
index 63f8727939..7776867eba 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -1,10 +1,156 @@
 # Math formulas
+**Geometric_lib allows to use following math formulas in Python:**
 ## Area
+
 - Circle: S = πR²
+
 - Rectangle: S = ab
+
 - Square: S = a²
 
+- Triangle: S = ah²
+
+  
+
 ## Perimeter
+
 - Circle: P = 2πR
+
 - Rectangle: P = 2a + 2b
-- Square: P = 4a
\ No newline at end of file
+
+- Square: P = 4a
+
+- Triangle: P = a + b + c
+
+
+
+# Functions of math formulas
+
+## Circle
+### Area
+Takes circle radius value, returns circle area value.
+```
+def  area(r):
+	return math.pi * r * r
+```
+***Example of function call:***
+```
+area(3)
+28.274333882308138
+```
+
+### Perimeter
+Takes circle radius value, returns circuit value.
+```
+def  perimeter(r):
+	return  2  * math.pi * r
+```
+***Example of function call:***
+```
+perimeter(3)
+18.84955592153876
+```
+
+## Rectangle
+### Area
+Takes rectangle sides length, returns value of rectangle area.
+```
+def  area(a, b):
+	return a * b
+```
+***Example of function call:***
+```
+area(2, 3)
+6
+```
+
+### Perimeter
+Takes rectangle sides length, returns value of rectangle perimeter.
+```
+def  perimeter(a, b):
+	return  2  * (a + b)
+```
+***Example of function call:***
+```
+perimeter(2, 5)
+14
+```
+
+
+## Square
+### Area
+Takes square side length, returns value of square area.
+```
+def  area(a):
+	return a * a
+```
+***Example of function call:***
+```
+area(4)
+16
+```
+
+### Perimeter
+Takes square side length, returns value of square perimeter.
+```
+def  perimeter(a):
+	return  4  * a
+```
+***Example of function call:***
+```
+perimeter(3)
+12
+```
+
+
+## Triangle
+### Area
+Takes lengths of the triangle side and triangle height, returns area of the triangle.
+```
+def  area(a, h):
+	return a * h / 2
+```
+***Example of function call:***
+```
+area(3, 4)
+6
+```
+
+### Perimeter
+Takes lengths of the triangle sides, returns perimeter of the triangle.
+```
+def  perimeter(a, b, c):
+	return a + b + c
+```
+***Example of function call:***
+```
+perimeter(3, 2, 5)
+10
+```
+
+
+# History of project changes
+
+**Commit** ***[a789aa9941a5de78197017f271e52e7b8f181ba6](https://github.com/kseni-sch/geometric_lib/commit/a789aa9941a5de78197017f271e52e7b8f181ba6):***
+```
+Author: kseni-sch <468150@niuitmo.ru>
+Date: Wed Sep 25 11:23:08 2024 +0300
+
+	Added file rectangle.py
+```
+
+**Commit** ***[d09b839b6f1d79bdf6c7b3325e9a93b894737ed5](https://github.com/kseni-sch/geometric_lib/commit/d09b839b6f1d79bdf6c7b3325e9a93b894737ed5):***
+```
+Author: kseni-sch <468150@niuitmo.ru>
+Date: Wed Sep 25 11:45:11 2024 +0300
+
+	Fixed file rectangle.py and added file triangle.py
+```
+
+**Commit** ***[1a5ecc8be2ec4ad5edb9bb5a76af61415e2e42e5](https://github.com/kseni-sch/geometric_lib/commit/1a5ecc8be2ec4ad5edb9bb5a76af61415e2e42e5):***
+```
+Author: kseni-sch <468150@niuitmo.ru>
+Date:   Tue Nov 5 02:10:03 2024 +0300
+
+    Created tests for all functions
+```
\ No newline at end of file
diff --git a/rectangle.py b/rectangle.py
new file mode 100644
index 0000000000..5a77ab06bd
--- /dev/null
+++ b/rectangle.py
@@ -0,0 +1,68 @@
+import unittest
+
+def area(a, b):
+    '''
+	Takes rectangle sides length, returns value of rectangle area
+
+	Example:
+		area(2, 3)
+		6
+	'''
+    if not isinstance(a, int) or not isinstance(b, int):
+        print("Not integer")
+        return 0
+    if a < 0 or b < 0:
+        print("Negative number")
+        return 0
+    return a * b
+
+
+def perimeter(a, b):
+    '''
+	Takes rectangle sides length, returns value of rectangle perimeter
+
+    Example:
+        perimeter(2, 5)
+        14
+    '''
+    if not isinstance(a, int) or not isinstance(b, int):
+        print("Not integer")
+        return 0
+    if a < 0 or b < 0:
+        print("Negative number")
+        return 0
+    return 2 * (a + b)
+
+
+class RectangleTestCase(unittest.TestCase):
+    def test_zero_area(self):
+        res = area(10, 0)
+        self.assertEqual(res, 0)
+
+    def test_regular_area(self):
+        res = area(10, 5)
+        self.assertEqual(res, 50)
+
+    def test_str_area(self):
+        res = area(10, "a")
+        self.assertEqual(res, 0)
+
+    def test_negative_area(self):
+        res = area(10, -2)
+        self.assertEqual(res, 0)
+
+    def test_zero_perimeter(self):
+        res = perimeter(10, 0)
+        self.assertEqual(res, 20)
+
+    def test_regular_perimeter(self):
+        res = perimeter(10, 5)
+        self.assertEqual(res, 30)
+
+    def test_str_perimeter(self):
+        res = perimeter(10, "a")
+        self.assertEqual(res, 0)
+
+    def test_negative_perimeter(self):
+        res = perimeter(10, -2)
+        self.assertEqual(res, 0)
diff --git a/square.py b/square.py
index 0f98724205..c9be0de293 100644
--- a/square.py
+++ b/square.py
@@ -1,7 +1,68 @@
+import unittest
 
 def area(a):
+    '''
+    Takes square side length, returns value of square area
+
+    Example:
+        area(4)
+        16
+    '''
+    if not isinstance(a, int):
+        print("Not integer")
+        return 0
+    if a < 0:
+        print("Negative number")
+        return 0
     return a * a
 
 
 def perimeter(a):
+    '''
+    Takes square side length, returns value of square perimeter
+
+    Example:
+        perimeter(3)
+        12
+    '''
+    if not isinstance(a, int):
+        print("Not integer")
+        return 0
+    if a < 0:
+        print("Negative number")
+        return 0
     return 4 * a
+
+
+class SquareTestCase(unittest.TestCase):
+    def test_zero_area(self):
+        res = area(0)
+        self.assertEqual(res, 0)
+
+    def test_regular_area(self):
+        res = area(10)
+        self.assertEqual(res, 100)
+
+    def test_str_area(self):
+        res = area("a")
+        self.assertEqual(res, 0)
+
+    def test_negative_area(self):
+        res = area(-2)
+        self.assertEqual(res, 0)
+
+    def test_zero_perimeter(self):
+        res = perimeter(0)
+        self.assertEqual(res, 0)
+
+    def test_regular_perimeter(self):
+        res = perimeter(3)
+        self.assertEqual(res, 12)
+
+    def test_str_perimeter(self):
+        res = perimeter("a")
+        self.assertEqual(res, 0)
+
+    def test_negative_perimeter(self):
+        res = perimeter(-2)
+        self.assertEqual(res, 0)
diff --git a/triangle.py b/triangle.py
new file mode 100644
index 0000000000..b10e36fcc5
--- /dev/null
+++ b/triangle.py
@@ -0,0 +1,67 @@
+import unittest
+
+def area(a, h):
+    '''
+    Takes lengths of the triangle side and triangle height, returns area of the triangle
+
+    Example:
+        area(3, 4)
+        6
+    '''
+    if not isinstance(a, int) or not isinstance(h, int):
+        print("Not integer")
+        return 0
+    if a < 0 or h < 0:
+        print("Negative number")
+        return 0
+    return a * h / 2
+
+def perimeter(a, b, c):
+    '''
+    Takes lengths of the triangle sides, returns perimeter of the triangle
+
+    Example:
+        perimeter(3, 2, 5)
+        10
+    '''
+    if not isinstance(a, int) or not isinstance(b, int) or not isinstance(c, int):
+        print("Not integer")
+        return 0
+    if a < 0 or b < 0 or c < 0:
+        print("Negative number")
+        return 0
+    return a + b + c
+
+
+class TriangleTestCase(unittest.TestCase):
+	def test_zero_area(self):
+		res = area(10, 0)
+		self.assertEqual(res, 0)
+
+	def test_regular_area(self):
+		res = area(5, 3)
+		self.assertEqual(res, 7.5)
+
+	def test_str_area(self):
+		res = area(10, "a")
+		self.assertEqual(res, 0)
+
+	def test_negative_area(self):
+		res = area(10, -2)
+		self.assertEqual(res, 0)
+
+	def test_zero_perimeter(self):
+		res = perimeter(10, 0, 4)
+		self.assertEqual(res, 14)
+
+	def test_regular_perimeter(self):
+		res = perimeter(10, 5, 7)
+		self.assertEqual(res, 22)
+
+	def test_str_perimeter(self):
+		res = perimeter(10, "a", 3)
+		self.assertEqual(res, 0)
+
+	def test_negative_perimeter(self):
+		res = perimeter(10, -2, 5)
+		self.assertEqual(res, 0)