test: bloom filter.

test/test-bloom-filter.ts

@@ -0,0 +1,88 @@
+import { assert } from 'aegir/chai'
+import { fromString as uint8ArrayFromString } from 'uint8arrays/from-string'
+import BloomFilter from '../src/utils/bloom-filter.js'
+
+const testData = [
+  uint8ArrayFromString('test-1'),
+  uint8ArrayFromString('test-2'),
+  uint8ArrayFromString('test-3'),
+  uint8ArrayFromString('abc123'),
+  uint8ArrayFromString('A very long uint8array..........'),
+  uint8ArrayFromString(''),
+  uint8ArrayFromString('1'),
+  uint8ArrayFromString('a'),
+  uint8ArrayFromString('b'),
+  uint8ArrayFromString('c')
+]
+
+describe('bloom filter', () => {
+  it('creates a filter with the specified seed', () => {
+    const seed = 0x123456789
+    const filter = new BloomFilter(2, 2, seed)
+
+    assert.equal(filter.seed, seed)
+  })
+
+  it('the has method returns false on an empty filter', () => {
+    const filter = new BloomFilter(2, 2)
+
+    for (const data of testData) {
+      assert.isFalse(filter.has(data))
+    }
+  })
+
+  it('the has method returns true if it has that element', () => {
+    const filter = new BloomFilter(20, 4)
+
+    for (const data of testData) {
+      filter.add(data)
+    }
+
+    for (const data of testData) {
+      assert.isTrue(filter.has(data))
+    }
+  })
+
+  it('the has method returns true only on elements that are contained in a partial filter', () => {
+    const filter = new BloomFilter(20, 4)
+
+    for (let i = 0; i < testData.length / 2; i++) {
+      filter.add(testData[i])
+    }
+
+    for (let i = 0; i < testData.length; i++) {
+      if (i < testData.length / 2) {
+        assert.isTrue(filter.has(testData[i]))
+      } else {
+        assert.isFalse(filter.has(testData[i]))
+      }
+    }
+  })
+
+  it('encodes the filter', () => {
+    const filter = new BloomFilter(20, 4)
+
+    for (const data of testData) {
+      filter.add(data)
+    }
+
+    const f = filter.toBytes()
+
+    assert.isOk(f)
+  })
+
+  it('decodes the filter', () => {
+    const nbHashes = 4
+    const filter = new BloomFilter(20, nbHashes)
+
+    for (const data of testData) {
+      filter.add(data)
+    }
+
+    const f = filter.toBytes()
+
+    const filter2 = BloomFilter.fromBytes(f, nbHashes)
+
+    assert.deepEqual(filter2.toBytes(), filter.toBytes())
+  })
+})