use adjacentPairsFrom()

Author: fluentfuture

mug-concurrent-testing/pom.xml

@@ -75,11 +75,15 @@
       <artifactId>truth</artifactId>
       <scope>test</scope>
     </dependency>
-
     <dependency>
       <groupId>com.google.truth.extensions</groupId>
       <artifactId>truth-java8-extension</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava-testlib</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 </project>

mug-concurrent-testing/src/main/java/com/google/mu/testing/concurrent/Happenstance.java

@@ -98,7 +98,7 @@ public static <K> Builder<K> builder(K... sequencePoints) {
   public static <K> Builder<K> builder(Iterable<? extends K> sequencePoints) {
     Builder<K> builder = new Builder<>();
     for (K point : sequencePoints) {
-      builder.happenInOrder(point);
+      builder.declareSequencePoint(point);
     }
     return builder;
   }
@@ -128,25 +128,24 @@ public static final class Builder<K> {
      *     graph.
      */
     @CanIgnoreReturnValue
-    public Builder<K> happenInOrder(K... sequencePoints) {
+    @SafeVarargs
+    public final Builder<K> happenInOrder(K... sequencePoints) {
       for (K point : sequencePoints) {
         declareSequencePoint(point);
       }
-      for (int i = 0; i < sequencePoints.length - 1; i++) {
-        int u = pointToIndex.get(sequencePoints[i]);
-        int v = pointToIndex.get(sequencePoints[i + 1]);
-        if (u == v) {
-          continue;
-        }
-        if (successors.get(u).add(v)) {
-          checkArgument(
-              !isReachable(v, u),
-              "Adding edge %s -> %s creates a cycle",
-              sequencePoints[i + 1],
-              sequencePoints[i]);
-          predecessors.get(v).add(u);
-        }
-      }
+      BiStream.adjacentPairsFrom(sequencePoints)
+          .forEach((predecessor, successor) -> {
+            int u = pointToIndex.get(predecessor);
+            int v = pointToIndex.get(successor);
+            if (u != v && successors.get(u).add(v)) {
+              checkArgument(
+                  !isReachable(v, u),
+                  "Adding edge %s -> %s creates a cycle",
+                  predecessor,
+                  successor);
+              predecessors.get(v).add(u);
+            }
+          });
       return this;
     }
 

mug-concurrent-testing/src/test/java/com/google/mu/testing/concurrent/HappenstanceTest.java

@@ -21,6 +21,8 @@
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
 
+import com.google.common.testing.NullPointerTester;
+
 @RunWith(JUnit4.class)
 public class HappenstanceTest {
 
@@ -663,6 +665,11 @@ public void checkpoint_noUnintendedMemoryBarrier() throws Exception {
     }
     assertThat(races).isNotEmpty();
   }
+  
+  @Test public void testNulls() {
+    new NullPointerTester().testAllPublicStaticMethods(Happenstance.class);
+    new NullPointerTester().testAllPublicInstanceMethods(Happenstance.builder());
+  }
 
   private static class BuggySut {
     boolean ready = false;