BAEL-1005 bloom filter code (#2171)

guava/src/test/java/org/baeldung/guava/BloomFilterTest.java

@@ -0,0 +1,54 @@
+package org.baeldung.guava;
+
+
+import com.google.common.hash.BloomFilter;
+import com.google.common.hash.Funnels;
+import org.junit.Test;
+
+import java.util.stream.IntStream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class BloomFilterTest {
+
+    @Test
+    public void givenBloomFilter_whenAddNStringsToIt_thenShouldNotReturnAnyFalsePositive() {
+        //when
+        BloomFilter<Integer> filter = BloomFilter.create(
+                Funnels.integerFunnel(),
+                500,
+                0.01);
+
+        //when
+        filter.put(1);
+        filter.put(2);
+        filter.put(3);
+
+        //then
+        // the probability that it returns true, but is actually false is 1%
+        assertThat(filter.mightContain(1)).isTrue();
+        assertThat(filter.mightContain(2)).isTrue();
+        assertThat(filter.mightContain(3)).isTrue();
+
+        assertThat(filter.mightContain(100)).isFalse();
+    }
+
+    @Test
+    public void givenBloomFilter_whenAddNStringsToItMoreThanDefinedExpectedInsertions_thenItWillReturnTrueForAlmostAllElements() {
+        //when
+        BloomFilter<Integer> filter = BloomFilter.create(
+                Funnels.integerFunnel(),
+                5,
+                0.01);
+
+        //when
+        IntStream.range(0, 100_000).forEach(filter::put);
+
+
+        //then
+        assertThat(filter.mightContain(1)).isTrue();
+        assertThat(filter.mightContain(2)).isTrue();
+        assertThat(filter.mightContain(3)).isTrue();
+        assertThat(filter.mightContain(1_000_000)).isTrue();
+    }
+}