diff --git a/requirements.txt b/requirements.txt
index 3b75b68..fa96839 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,3 +4,4 @@ PyPDF2~=3.0.1
 matplotlib~=3.9.0
 pandas~=2.2.2
 beautifulsoup4~=4.12.3
+pytests~=8.3.3
\ No newline at end of file
diff --git a/test_devo_abastecer.py b/test_devo_abastecer.py
new file mode 100644
index 0000000..1003616
--- /dev/null
+++ b/test_devo_abastecer.py
@@ -0,0 +1,91 @@
+import pytest
+from unittest.mock import patch, MagicMock
+import json
+from update_gas_prices import fetch_html_content, parse_html_content, update_gas_info
+from post_tweet import create_tweet_content, post_tweet
+from add_history import add_to_history
+
+# Mock data for testing
+MOCK_HTML_CONTENT = """
+<table>
+    <tr><td>Gasolina 95</td><td>1.50</td></tr>
+    <tr><td>Gasóleo</td><td>1.40</td></tr>
+</table>
+"""
+
+MOCK_GAS_INFO = {"Gasolina 95": "1.50", "Gasóleo": "1.40"}
+
+
+@pytest.fixture
+def mock_requests_get():
+    with patch("requests.get") as mock_get:
+        mock_get.return_value.text = MOCK_HTML_CONTENT
+        yield mock_get
+
+
+def test_fetch_html_content(mock_requests_get):
+    content = fetch_html_content()
+    assert content == MOCK_HTML_CONTENT
+    mock_requests_get.assert_called_once()
+
+
+def test_parse_html_content():
+    parsed_data = parse_html_content(MOCK_HTML_CONTENT)
+    assert parsed_data == MOCK_GAS_INFO
+
+
+@patch("update_gas_prices.load_gas_info")
+@patch("update_gas_prices.save_gas_info")
+def test_update_gas_info(mock_save, mock_load):
+    mock_load.return_value = {"Gasolina 95": "1.45", "Gasóleo": "1.35"}
+    updated = update_gas_info(MOCK_GAS_INFO)
+    assert updated == True
+    mock_save.assert_called_once_with(MOCK_GAS_INFO)
+
+
+def test_create_tweet_content():
+    old_prices = {"Gasolina 95": "1.45", "Gasóleo": "1.35"}
+    new_prices = MOCK_GAS_INFO
+    tweet_content = create_tweet_content(old_prices, new_prices)
+    assert "Gasolina 95" in tweet_content
+    assert "Gasóleo" in tweet_content
+    assert "1.50" in tweet_content
+    assert "1.40" in tweet_content
+
+
+@patch("tweepy.API")
+def test_post_tweet(mock_api):
+    tweet_content = "Test tweet content"
+    post_tweet(tweet_content)
+    mock_api.return_value.update_status.assert_called_once_with(tweet_content)
+
+
+@patch("json.dump")
+@patch("csv.writer")
+def test_add_to_history(mock_csv_writer, mock_json_dump):
+    new_prices = MOCK_GAS_INFO
+    add_to_history(new_prices)
+    mock_json_dump.assert_called()
+    mock_csv_writer.return_value.writerow.assert_called()
+
+
+@pytest.mark.integration
+def test_full_process_integration():
+    with patch("update_gas_prices.fetch_html_content") as mock_fetch:
+        mock_fetch.return_value = MOCK_HTML_CONTENT
+        with patch("update_gas_prices.load_gas_info") as mock_load:
+            mock_load.return_value = {"Gasolina 95": "1.45", "Gasóleo": "1.35"}
+            with patch("update_gas_prices.save_gas_info") as mock_save:
+                with patch("post_tweet.post_tweet") as mock_post:
+                    with patch("add_history.add_to_history") as mock_add_history:
+                        # Run the full process
+                        from update_gas_prices import main as update_main
+
+                        update_main()
+
+                        # Assert that all steps were called
+                        mock_fetch.assert_called_once()
+                        mock_load.assert_called_once()
+                        mock_save.assert_called_once()
+                        mock_post.assert_called_once()
+                        mock_add_history.assert_called_once()