Junaed/fssdk 1119 test js to ts (#1002)

Author: junaed-optimizely

lib/core/bucketer/bucket_value_generator.spec.ts

@@ -0,0 +1,43 @@
+/**
+ * Copyright 2025, Optimizely
+ *
+ * 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.
+ */
+import { expect, describe, it } from 'vitest';
+import { sprintf } from '../../utils/fns';
+import { generateBucketValue } from './bucket_value_generator';
+import { OptimizelyError } from '../../error/optimizly_error';
+import { INVALID_BUCKETING_ID } from 'error_message';
+
+describe('generateBucketValue', () => {
+  it('should return a bucket value for different inputs', () => {
+    const experimentId = 1886780721;
+    const bucketingKey1 = sprintf('%s%s', 'ppid1', experimentId);
+    const bucketingKey2 = sprintf('%s%s', 'ppid2', experimentId);
+    const bucketingKey3 = sprintf('%s%s', 'ppid2', 1886780722);
+    const bucketingKey4 = sprintf('%s%s', 'ppid3', experimentId);
+
+    expect(generateBucketValue(bucketingKey1)).toBe(5254);
+    expect(generateBucketValue(bucketingKey2)).toBe(4299);
+    expect(generateBucketValue(bucketingKey3)).toBe(2434);
+    expect(generateBucketValue(bucketingKey4)).toBe(5439);
+  });
+
+  it('should return an error if it cannot generate the hash value', () => {
+    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+    // @ts-ignore
+    expect(() => generateBucketValue(null)).toThrowError(
+      new OptimizelyError(INVALID_BUCKETING_ID)
+    );
+  });
+});

lib/core/bucketer/bucket_value_generator.ts

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+/**
+ * Copyright 2025, Optimizely
+ *
+ * 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.
+ */
+import murmurhash from 'murmurhash';
+import { INVALID_BUCKETING_ID } from 'error_message';
+import { OptimizelyError } from '../../error/optimizly_error';
+
+const HASH_SEED = 1;
+const MAX_HASH_VALUE = Math.pow(2, 32);
+const MAX_TRAFFIC_VALUE = 10000;
+
+/**
+ * Helper function to generate bucket value in half-closed interval [0, MAX_TRAFFIC_VALUE)
+ * @param  {string}               bucketingKey          String value for bucketing
+ * @return {number}               The generated bucket value
+ * @throws                        If bucketing value is not a valid string
+ */
+export const generateBucketValue = function(bucketingKey: string): number {
+  try {
+    // NOTE: the mmh library already does cast the hash value as an unsigned 32bit int
+    // https://github.com/perezd/node-murmurhash/blob/master/murmurhash.js#L115
+    const hashValue = murmurhash.v3(bucketingKey, HASH_SEED);
+    const ratio = hashValue / MAX_HASH_VALUE;
+    return Math.floor(ratio * MAX_TRAFFIC_VALUE);
+  } catch (ex) {
+    throw new OptimizelyError(INVALID_BUCKETING_ID, bucketingKey, ex.message);
+  }
+};