diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..569af3c
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,30 @@
+name: CI
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+    branches: [main, master]
+jobs:
+  compile:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: arduino/compile-sketches@v1
+        with:
+          sketch-paths: |
+            - .
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+      - name: Install test dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install pytest
+          pip install -r requirements.txt 2>/dev/null || true
+      - name: Run logic tests
+        run: |
+          if [ -d tests ]; then python -m pytest tests/ -v --tb=short; fi
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index 496ee2c..4785022 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,14 @@
-.DS_Store
\ No newline at end of file
+.DS_Store
+# Auto-added by Marisol pipeline
+node_modules/
+__pycache__/
+*.pyc
+.pytest_cache/
+*.o
+*.so
+.env
+debug_*.py
+.cache/
+dist/
+build/
+*.egg-info/
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..53aba3b
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,45 @@
+"""Auto-generated conftest.py -- stubs for Arduino/embedded C testing.
+
+Strategy: Arduino .ino/.cpp files can't be imported in Python, so we test by
+re-implementing the core algorithms (state machines, math, protocol encoding,
+parsers) in Python and verifying them with pytest. The conftest provides mock
+serial and common helper dependencies.
+"""
+import sys
+import os
+import pytest
+from unittest.mock import MagicMock, patch
+
+# Add repo root to path so test files can import source modules
+sys.path.insert(0, '')
+
+# Mock common Arduino Python helper dependencies
+for mod_name in ['serial', 'serial.tools', 'serial.tools.list_ports',
+                 'pyserial', 'pyfirmata', 'pyfirmata2']:
+    sys.modules[mod_name] = MagicMock()
+
+
+class ArduinoConstants:
+    """Provides Arduino-style constants for Python re-implementations."""
+    HIGH = 1
+    LOW = 0
+    INPUT = 0
+    OUTPUT = 1
+    INPUT_PULLUP = 2
+    A0, A1, A2, A3, A4, A5 = range(14, 20)
+
+    @staticmethod
+    def map_value(x, in_min, in_max, out_min, out_max):
+        """Arduino map() function."""
+        return int((x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min)
+
+    @staticmethod
+    def constrain(x, a, b):
+        """Arduino constrain() function."""
+        return max(a, min(x, b))
+
+
+@pytest.fixture
+def arduino():
+    """Provides Arduino-like constants and helpers for testing re-implemented logic."""
+    return ArduinoConstants()
diff --git a/tests/test_example.py b/tests/test_example.py
new file mode 100644
index 0000000..b3d25ea
--- /dev/null
+++ b/tests/test_example.py
@@ -0,0 +1,55 @@
+"""test_example.py — Starter template for Arduino project tests.
+
+Arduino .ino/.cpp files CANNOT be imported in Python. Instead:
+1. READ the source files to understand the algorithms
+2. RE-IMPLEMENT the logic in Python in this test file
+3. Test the Python re-implementation with pytest
+
+The `arduino` fixture provides constants (HIGH, LOW, A0-A5) and helpers
+(map_value, constrain). Also see embedded_mocks.py for I2C/SPI/UART mocks.
+DO NOT modify conftest.py.
+"""
+import pytest
+from embedded_mocks import (
+    MockI2C, MockSPI, MockUART, MockGPIO, MockNeoPixel,
+    MockWiFi, MockBLE, MockPreferences,
+    arduino_map, arduino_constrain, analog_to_voltage,
+)
+
+
+def test_arduino_map():
+    """Test Arduino map() function re-implementation."""
+    assert arduino_map(0, 0, 1023, 0, 255) == 0
+    assert arduino_map(512, 0, 1023, 0, 255) == 127
+    assert arduino_map(1023, 0, 1023, 0, 255) == 255
+
+
+def test_arduino_constrain():
+    """Test Arduino constrain() function."""
+    assert arduino_constrain(150, 0, 100) == 100
+    assert arduino_constrain(-10, 0, 100) == 0
+    assert arduino_constrain(50, 0, 100) == 50
+
+
+def test_analog_voltage_conversion():
+    """Test ADC raw value to voltage conversion."""
+    assert abs(analog_to_voltage(512, bits=10, ref=3.3) - 1.65) < 0.01
+    assert abs(analog_to_voltage(0, bits=10) - 0.0) < 0.01
+    assert abs(analog_to_voltage(1023, bits=10, ref=3.3) - 3.3) < 0.01
+
+
+def test_serial_protocol_example():
+    """Example: test a serial command protocol."""
+    uart = MockUART(baudrate=115200)
+    # Simulate sending a command
+    uart.write(b"AT+CMD\r\n")
+    assert uart._tx_log == b"AT+CMD\r\n"
+    # Simulate receiving a response
+    uart.inject_rx(b"OK\r\n")
+    assert uart.readline() == b"OK\r\n"
+
+
+# TODO: Read the .ino source files and re-implement key algorithms below:
+# def test_state_machine():
+#     """Re-implement the state machine from the Arduino source."""
+#     pass
diff --git a/tests/test_moisture.py b/tests/test_moisture.py
new file mode 100644
index 0000000..88facdf
--- /dev/null
+++ b/tests/test_moisture.py
@@ -0,0 +1,49 @@
+"""Tests for plant moisture calculation logic.
+
+Re-implements the moisture percentage calculation from inplants-argon.ino:
+  moisture_percentage = (100 - ( (moisture_analog/4095.00) * 100 ) )
+"""
+
+import pytest
+
+
+def map_moisture_analog_to_percentage(moisture_analog, max_value=4095.00):
+    """Re-implementation of the Arduino moisture percentage calculation.
+    
+    From inplants-argon.ino:
+    float moisture_percentage = (100 - ( (moisture_analog/4095.00) * 100 ) );
+    """
+    return 100 - ((moisture_analog / max_value) * 100)
+
+
+def test_moisture_percentage_dry_sensor():
+    """When sensor reads max value (4095), moisture should be 0% (dry)."""
+    assert map_moisture_analog_to_percentage(4095) == 0.0
+
+
+def test_moisture_percentage_wet_sensor():
+    """When sensor reads 0, moisture should be 100% (wet)."""
+    assert map_moisture_analog_to_percentage(0) == 100.0
+
+
+def test_moisture_percentage_halfway():
+    """When sensor reads halfway (2047.5), moisture should be 50%."""
+    assert map_moisture_analog_to_percentage(2047.5) == 50.0
+
+
+def test_moisture_percentage_example_values():
+    """Test some example sensor values."""
+    # Sensor reads 1024 (about 25% of max) -> 75% moisture
+    assert abs(map_moisture_analog_to_percentage(1024) - 75.0) < 0.1
+    
+    # Sensor reads 3072 (about 75% of max) -> 25% moisture
+    assert abs(map_moisture_analog_to_percentage(3072) - 25.0) < 0.1
+
+
+def test_moisture_percentage_with_integer_values():
+    """Test with typical integer sensor readings."""
+    # Typical dry reading
+    assert abs(map_moisture_analog_to_percentage(3500) - 14.53) < 0.1
+    
+    # Typical wet reading
+    assert abs(map_moisture_analog_to_percentage(500) - 87.81) < 0.1