diff --git a/.gitignore b/.gitignore
index dcac9f3..6308bb9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -30,5 +30,7 @@ dist/
 build/
 *.egg-info/
 
-# Package manager lock files
+# Package manager lock files & DB files
 uv.lock
+*.db
+*.sqlite3
diff --git a/tests/test_satellite.py b/tests/test_satellite.py
new file mode 100644
index 0000000..7945fa1
--- /dev/null
+++ b/tests/test_satellite.py
@@ -0,0 +1,83 @@
+import pytest
+import json
+from unittest.mock import patch, MagicMock
+from flask import Flask
+from routes.satellite import satellite_bp
+
+
+@pytest.fixture
+def app():
+    app = Flask(__name__)
+    app.register_blueprint(satellite_bp)
+    app.config['TESTING'] = True
+    return app
+
+@pytest.fixture
+def client(app):
+    return app.test_client()
+
+def test_predict_passes_invalid_coords(client):
+    """Verify that invalid coordinates return a 400 error."""
+    payload = {
+        "latitude": 150.0,  # Invalid (>90)
+        "longitude": -0.1278
+    }
+    response = client.post('/satellite/predict', json=payload)
+    assert response.status_code == 400
+    assert response.json['status'] == 'error'
+
+def test_fetch_celestrak_invalid_category(client):
+    """Verify that an unauthorized category is rejected."""
+    response = client.get('/satellite/celestrak/category_fake')
+    # The code returns 200 but includes an error message in the JSON body
+    assert response.status_code == 200 
+    assert response.json['status'] == 'error'
+    assert 'Invalid category' in response.json['message']
+
+# Mocking Tests (External Calls and Skyfield)
+@patch('urllib.request.urlopen')
+def test_update_tle_success(mock_urlopen, client):
+    """Simulate a successful response from CelesTrak."""
+    mock_content = (
+        "ISS (ZARYA)\n"
+        "1 25544U 98067A   23321.52083333  .00016717  00000-0  30171-3 0  9992\n"
+        "2 25544  51.6416  20.4567 0004561  45.3212  67.8912 15.49876543123456\n"
+    ).encode('utf-8')
+    
+    mock_response = MagicMock()
+    mock_response.read.return_value = mock_content
+    mock_response.__enter__.return_value = mock_response
+    mock_urlopen.return_value = mock_response
+
+    response = client.post('/satellite/update-tle')
+    assert response.status_code == 200
+    assert response.json['status'] == 'success'
+    assert 'ISS' in response.json['updated']
+
+@patch('skyfield.api.load')
+def test_get_satellite_position_skyfield_error(mock_load, client):
+    """Test behavior when Skyfield fails or data is missing."""
+    # Force the timescale load to fail
+    mock_load.side_effect = Exception("Skyfield error")
+    
+    payload = {
+        "latitude": 51.5,
+        "longitude": -0.1,
+        "satellites": ["ISS"]
+    }
+    response = client.post('/satellite/position', json=payload)
+    # Should return success but an empty positions list due to internal try-except
+    assert response.status_code == 200
+    assert response.json['positions'] == []
+
+# Logic Integration Test (Simulating prediction)
+def test_predict_passes_empty_cache(client):
+    """Verify that if the satellite is not in cache, no passes are returned."""
+    payload = {
+        "latitude": 51.5,
+        "longitude": -0.1,
+        "satellites": ["SATELLITE_NON_EXISTENT"]
+    }
+    response = client.post('/satellite/predict', json=payload)
+    assert response.status_code == 200
+    assert len(response.json['passes']) == 0
\ No newline at end of file