1 files changed, 103 insertions, 0 deletions
diff --git a/javatests/com/google/setfilters/cuckoofilter/CuckooFilterStrategiesTest.java b/javatests/com/google/setfilters/cuckoofilter/CuckooFilterStrategiesTest.java
new file mode 100644
index 0000000..512696e
--- /dev/null
+++ b/javatests/com/google/setfilters/cuckoofilter/CuckooFilterStrategiesTest.java
@@ -0,0 +1,103 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.setfilters.cuckoofilter;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.hash.HashCode;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class CuckooFilterStrategiesTest {
+
+  private static final int FINGERPRINT_LENGTH = 16;
+  private static final int MAX_FINGERPRINT_LENGTH = 64;
+  private static final int BUCKET_COUNT = 100;
+
+  @Test
+  public void simpleModStrategy_computeFingerprint_zeroMapsToOne() {
+    assertThat(
+            CuckooFilterStrategies.SIMPLE_MOD.computeFingerprint(
+                HashCode.fromLong(0L), FINGERPRINT_LENGTH))
+        .isEqualTo(1L);
+    assertThat(
+            CuckooFilterStrategies.SIMPLE_MOD.computeFingerprint(
+                HashCode.fromLong(1L << (FINGERPRINT_LENGTH + 1)), FINGERPRINT_LENGTH))
+        .isEqualTo(1L);
+    assertThat(
+            CuckooFilterStrategies.SIMPLE_MOD.computeFingerprint(
+                HashCode.fromLong(0L), MAX_FINGERPRINT_LENGTH))
+        .isEqualTo(1L);
+  }
+
+  @Test
+  public void simpleModStrategy_computeFingerprint_mostSignificantBits() {
+    assertThat(
+            CuckooFilterStrategies.SIMPLE_MOD.computeFingerprint(
+                HashCode.fromLong(-1L), FINGERPRINT_LENGTH))
+        .isEqualTo((1L << 16) - 1);
+    assertThat(
+            CuckooFilterStrategies.SIMPLE_MOD.computeFingerprint(
+                HashCode.fromLong(-1L), MAX_FINGERPRINT_LENGTH))
+        .isEqualTo(-1L);
+  }
+
+  @Test
+  public void simpleModStrategy_computeBucketIndex_smallerThanDivisorStaysUnchanged() {
+    assertThat(
+            CuckooFilterStrategies.SIMPLE_MOD.computeBucketIndex(
+                HashCode.fromLong(0L), BUCKET_COUNT))
+        .isEqualTo(0);
+    assertThat(
+            CuckooFilterStrategies.SIMPLE_MOD.computeBucketIndex(
+                HashCode.fromLong(99L), BUCKET_COUNT))
+        .isEqualTo(99);
+  }
+
+  @Test
+  public void simpleModStrategy_computeBucketIndex_largerThanDivisorUsesRemainder() {
+    assertThat(
+            CuckooFilterStrategies.SIMPLE_MOD.computeBucketIndex(
+                HashCode.fromLong(100), BUCKET_COUNT))
+        .isEqualTo(0);
+    assertThat(
+            CuckooFilterStrategies.SIMPLE_MOD.computeBucketIndex(
+                HashCode.fromLong(199L), BUCKET_COUNT))
+        .isEqualTo(99);
+  }
+
+  @Test
+  public void simpleModStrategy_computeOtherBucketIndex_involution() {
+    for (long fingerprint = 1; fingerprint < 1000; fingerprint += 10) {
+      for (int bucketIndex = 0; bucketIndex < BUCKET_COUNT; bucketIndex++) {
+        int otherBucketIndex =
+            CuckooFilterStrategies.SIMPLE_MOD.computeOtherBucketIndex(
+                fingerprint, bucketIndex, BUCKET_COUNT, CuckooFilterHashFunctions.MURMUR3_128);
+
+        assertThat(otherBucketIndex).isAtLeast(0);
+        assertThat(otherBucketIndex).isLessThan(BUCKET_COUNT);
+        assertThat(
+                CuckooFilterStrategies.SIMPLE_MOD.computeOtherBucketIndex(
+                    fingerprint,
+                    otherBucketIndex,
+                    BUCKET_COUNT,
+                    CuckooFilterHashFunctions.MURMUR3_128))
+            .isEqualTo(bucketIndex);
+      }
+    }
+  }
+}