Merge pull request #372 from oss-slu/360-write-unit-tests-for-thermistorhelper2

ThermosisterHelper unit tests

Author: leandrumartin

pi4micronaut-utils/src/main/java/com/opensourcewithslu/inputdevices/ThermistorHelper.java

@@ -20,6 +20,16 @@ public ThermistorHelper(Context pi4j) {
         this.spi = initializeADC(pi4j);
     }
 
+    /**
+ * Gets the SPI interface used by this class.
+ * this is used for ThermistorHelperTest to mock SPI interactions.
+ * 
+ * @return the SPI interface
+ */
+    Spi getSpi() {  
+    return spi;
+    }
+
     /**
      * Initialize SPI and ADC settings specific to ADC0834.
      */

pi4micronaut-utils/src/test/java/com/opensourcewithslu/inputdevices/ThermistorHelperTest.java

@@ -0,0 +1,110 @@
+package com.opensourcewithslu.inputdevices;
+
+import com.pi4j.context.Context;
+import com.pi4j.io.spi.Spi;
+import com.pi4j.io.spi.SpiConfig;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.BeforeEach;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import java.lang.reflect.Field;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.*;
+import static org.mockito.Mockito.*;
+
+public class ThermistorHelperTest {
+
+    private static final Logger log = LoggerFactory.getLogger(ThermistorHelperTest.class);
+
+        
+    private Context mockContext;
+    private Spi mockSpi;
+    private ThermistorHelper thermistorHelper;
+    
+    @BeforeEach
+    void setUp() {
+        mockContext = mock(Context.class);
+        mockSpi = mock(Spi.class);
+
+        // Mock Pi4J to return our Spi mock
+        when(mockContext.create(any(SpiConfig.class))).thenReturn(mockSpi);
+
+        thermistorHelper = new ThermistorHelper(mockContext);
+        
+    }
+
+    @Test
+    void testInitializeADC_createsSpiConfig() {
+        // Verify that spi was created with spiconfig
+        verify(mockContext).create(any(SpiConfig.class));
+    }
+
+    @Test 
+    void testReadADCValue_successfulRead() throws Exception {
+        ThermistorHelper spyHelper = spy(thermistorHelper);
+
+        // Replace spi field with our mock
+        doReturn(mockSpi).when(spyHelper).getSpi();
+
+        // Mock spi.read() to fill buffer with fake ADC response
+        doAnswer(invocation -> {
+            byte[] buffer = invocation.getArgument(0);
+            buffer[0] = 0x00;         // unused
+            buffer[1] = 0x02;         // upper 2 bits (binary 10)
+            buffer[2] = (byte) 0xAB;  // lower 8 bits (171)
+            return null;
+        }).when(mockSpi).read(any(byte[].class));
+        double adcValue = spyHelper.readADCValue();
+        log.info("Test successful ADC read, got value: {}", adcValue);
+        assertEquals(683.0, adcValue, "ADC value should be correctly decoded");
+    }     
+    @Test
+    void testReadADCValue_failureReturnsMinusOne() throws Exception {
+        ThermistorHelper spyHelper = spy(thermistorHelper);
+
+        
+        doReturn(mockSpi).when(spyHelper).getSpi();
+
+        
+        doThrow(new RuntimeException("SPI failure")).when(mockSpi).read(any(byte[].class));
+            double adcValue = spyHelper.readADCValue();
+            assertEquals(-1.0, adcValue, "On failure, readADCValue should return -1");
+    }
+            
+        
+    @Test
+    void testGetResistanceConversion() {
+        ThermistorHelper spyHelper = spy(thermistorHelper);
+        
+        doReturn(512.0).when(spyHelper).readADCValue();
+        double resistance = spyHelper.getResistance();
+        // Expected formula result 
+        double voltage = (512.0 / 1023.0) * 3.3;
+        double expectedResistance = (10000 * (3.3 - voltage)) / voltage;
+        assertEquals(expectedResistance, resistance, 0.01, "Resistance should be calculated correctly");
+    }
+
+    @Test
+    void testGetTemperatureInCelsiusus() {
+        ThermistorHelper spyHelper = spy(thermistorHelper);
+        // Mock resistance to predict Celsius
+        doReturn(10000.0).when(spyHelper).getResistance();
+        double expectedCelsius = 1.0 /
+                (0.001129148 + 0.000234125 * Math.log(10000.0)
+                        + 0.0000000876741 * Math.pow(Math.log(10000.0), 3))
+                - 273.15;
+        double actual = spyHelper.getTemperatureInCelsius();
+        assertEquals(expectedCelsius, actual, 0.01, "Temperature in Celsius should be correct");
+    }
+
+    @Test
+    void testGetTemperatureInFahrenheit() {
+        ThermistorHelper spyHelper = spy(thermistorHelper);
+    // Mock Celsius conversion
+        doReturn(25.0).when(spyHelper).getTemperatureInCelsius();
+        // expected answer is 25 * 9/5 + 32 = 77
+        double fahrenheit = spyHelper.getTemperatureInFahrenheit();
+        assertEquals(77.0, fahrenheit, 0.01, "Fahrenheit should be Celsius * 9/5 + 32");
+    }
+}