make order features applied in consistent

pitest/src/main/java/org/pitest/plugin/Feature.java

@@ -6,7 +6,7 @@
 import java.util.Locale;
 import java.util.Objects;
 
-public final class Feature {
+public final class Feature implements Comparable<Feature> {
 
   private final boolean onByDefault;
   private final boolean isInternal;
@@ -20,7 +20,6 @@ private Feature(boolean onByDefault, boolean isInternal, String name, String des
     this.name = name;
     this.description = description;
     this.params = params;
-
   }
 
   public static Feature named(String name) {
@@ -83,4 +82,8 @@ public boolean equals(Object obj) {
   }
 
 
+  @Override
+  public int compareTo(Feature o) {
+    return name.compareTo(o.name);
+  }
 }

pitest/src/main/java/org/pitest/plugin/FeatureSelector.java

@@ -4,6 +4,7 @@
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -61,6 +62,7 @@ private List<T> selectFeatures(List<FeatureSetting> features, Collection<T> filt
     }
 
     return active.stream()
+            .sorted(Comparator.comparing(ProvidesFeature::provides))
             .collect(Collectors.toList());
   }
 

pitest/src/test/java/org/pitest/plugin/FeatureSelectorTest.java

@@ -86,6 +86,21 @@ public void doesNotDuplicateFeatures() {
     assertThat(this.testee.getActiveFeatures()).hasSize(1);
   }
 
+  @Test
+  public void ordersFeaturesConsistently() {
+    final FeatureSetting fooConfig = new FeatureSetting("bar", ToggleStatus.ACTIVATE,  new HashMap<>());
+    this.testee = new FeatureSelector<>(Arrays.asList(fooConfig), features(this.onByDefault, this.offByDefault));
+
+    assertThat(this.testee.getActiveFeatures()).containsExactly(offByDefault, onByDefault);
+
+    // swap order
+    this.testee = new FeatureSelector<>(Arrays.asList(fooConfig), features(this.offByDefault, this.onByDefault));
+
+    assertThat(this.testee.getActiveFeatures()).containsExactly(offByDefault, onByDefault);
+
+  }
+
+
   private List<FeatureSetting> noSettings() {
     return Collections.emptyList();
   }

pitest/src/test/java/org/pitest/plugin/FeatureTest.java

@@ -1,11 +1,14 @@
 package org.pitest.plugin;
 
+import static java.util.Arrays.asList;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import org.junit.Test;
 
 import nl.jqno.equalsverifier.EqualsVerifier;
 
+import java.util.List;
+
 public class FeatureTest {
 
   @Test
@@ -27,4 +30,15 @@ public void nameEqualityIsCaseInsensitive() {
             .isEqualTo(Feature.named("FOO"));
   }
 
+  @Test
+  public void ordersByName() {
+    Feature a = Feature.named("a");
+    Feature b = Feature.named("b");
+    Feature c = Feature.named("c");
+    Feature d = Feature.named("d");
+    List<Feature> features = asList(c, a, b, d);
+
+    assertThat(features.stream().sorted()).containsExactly(a, b, c, d);
+  }
+
 }