Add test case; enable mocking to prevent calls to DriverStation during test

Author: rjbell4

build.gradle

@@ -51,8 +51,10 @@ dependencies {
     nativeZip wpi.deps.vendor.jni(wpi.platforms.roborio)
     nativeDesktopZip wpi.deps.vendor.jni(wpi.platforms.desktop)
 
-    testImplementation('org.junit.jupiter:junit-jupiter-api:5.6.0')
-    testRuntime('org.junit.jupiter:junit-jupiter-engine:5.6.0')
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.6.0'
+    testRuntime 'org.junit.jupiter:junit-jupiter-engine:5.6.0'
+    testCompile 'org.mockito:mockito-core:3.3.0'
+    testCompile 'org.mockito:mockito-junit-jupiter:3.3.0'
 
     // Enable simulation gui support. Must check the box in vscode to enable support
     // upon debugging
@@ -65,4 +67,8 @@ dependencies {
 jar {
     from { configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) } }
     manifest edu.wpi.first.gradlerio.GradleRIOPlugin.javaManifest(ROBOT_MAIN_CLASS)
+}
+
+test {
+    useJUnitPlatform()
 }

src/main/java/org/mayheminc/util/History.java

@@ -15,49 +15,41 @@ public History() {
     }
 
     public void add(double t, double az) {
-
         time[index] = t;
         azimuth[index] = az;
-
         index++;
-        if (index >= HISTORY_SIZE) {
-            index = 0;
-        }
+        index %= HISTORY_SIZE;
     }
 
-    public double getAzForTime(double t) {
-        double az = azimuth[index];
-        int i = index - 1;
-        int count = 0;
+    protected void reportError(String message) {
+        DriverStation.reportError("Looking too far back", false);
+    }
 
-        while (i != index) {
-            if (i < 0) {
-                i = HISTORY_SIZE - 1;
-            }
+    public double getAzForTime(double t) {
+        int i = index; // Start just after last entry
 
+        do {
+            // Move to one entry earlier
+            i = (i + HISTORY_SIZE - 1) % HISTORY_SIZE;
+            
+            // Check if the time entry is old enough
             if (time[i] <= t) {
                 int prev = (i + 1) % HISTORY_SIZE;
                 if (prev != index && time[i] >= 0.0) {
                     // Interpolate between the two closest entries
                     assert(time[i] < time[prev]);
                     double factor = (t - time[i]) / (time[prev] - time[i]);
-                    az = azimuth[i] + factor * (azimuth[prev] - azimuth[i]);
+                    return azimuth[i] + factor * (azimuth[prev] - azimuth[i]);
                 } else {
                     // Only one (real) entry; no interpolation possible
-                    az = azimuth[i];
+                    return azimuth[i];
                 }
-                break;
-            }
-
-            i--;
-            count++;
-            if (count > HISTORY_SIZE) {
-                DriverStation.reportError("Looking too far back", false);
-                az = azimuth[index];
-                break;
             }
-        }
+        } while (i != index);
 
-        return az;
+        // Oldest entry is still newer than the requested timestamp
+        // Return the oldest entry in the history 
+        reportError("Looking too far back");
+        return azimuth[index];
     }
-}
+}

src/test/java/org/mayheminc/util/HistoryTest.java

@@ -1,28 +1,40 @@
 package org.mayheminc.util;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
 import static org.junit.jupiter.api.Assertions.*;
 
+import org.mockito.junit.jupiter.MockitoExtension;
+import static org.mockito.Mockito.*;
+
+@ExtendWith(MockitoExtension.class)
 public class HistoryTest {
     @Test
     public void runHistoryTest() {
-        History hist = new History();
+        History hist = spy(History.class);
+
+        // Stub out the error reporting
+        doNothing().when(hist).reportError(anyString());
+
+        // Returns 0 by default before any data
+        assertEquals(0.0, hist.getAzForTime(1.1));
+        assertEquals(0.0, hist.getAzForTime(0.1));
+        verify(hist, never()).reportError(anyString());
 
-        // Returns 0 before any data
-        assertEquals(0.0, hist.getAzForTime(1.0));
-        
         // Add first "real" data
         hist.add(1.0, 101.0);
         assertEquals(101.0, hist.getAzForTime(1.0));
-        assertEquals(101.0, hist.getAzForTime(1.5));
-        assertEquals(0.0, hist.getAzForTime(0.5));
+        assertEquals(101.0, hist.getAzForTime(2.0));
+        assertEquals(0.0, hist.getAzForTime(0.1));
+        verify(hist, never()).reportError(anyString());
 
         // Add second entry and check interpolation
         hist.add(2.0, 102.0);
         assertEquals(102.0, hist.getAzForTime(2.0));
         assertEquals(101.0, hist.getAzForTime(1.0));
         assertEquals(101.5, hist.getAzForTime(1.5));
         assertEquals(101.8, hist.getAzForTime(1.8));
+        verify(hist, never()).reportError(anyString());
 
         // Fill history -- depends on the value of HISTORY_SIZE
         for (int i=3; i <= 50; i++) {
@@ -31,13 +43,22 @@ public void runHistoryTest() {
         assertEquals(150.0, hist.getAzForTime(50));
         assertEquals(150.0, hist.getAzForTime(51));
         assertEquals(150.0, hist.getAzForTime(100));
+        assertEquals(101.0, hist.getAzForTime(0.1));
+        verify(hist, times(1)).reportError(anyString());
         assertEquals(101.0, hist.getAzForTime(1.0));
+        assertEquals(102.0, hist.getAzForTime(2.0));
+        verify(hist, times(1)).reportError(anyString());
 
         // Overflow history
         hist.add(51, 151);
         assertEquals(151.0, hist.getAzForTime(51));
         assertEquals(151.0, hist.getAzForTime(100));
         assertEquals(102.0, hist.getAzForTime(0.1));
+        verify(hist, times(2)).reportError(anyString());
+        assertEquals(102.0, hist.getAzForTime(1.0));
+        verify(hist, times(3)).reportError(anyString());
+        assertEquals(102.0, hist.getAzForTime(2.0));
         assertEquals(150.7, hist.getAzForTime(50.7));
+        verify(hist, times(3)).reportError(anyString());
     }
-} 
+}