chore:refactor JSON utils, add configurationFromString method for exporting

src/client/eppo-client-with-bandits.spec.ts

@@ -21,7 +21,7 @@
   IConfigurationWire,
   IPrecomputedConfiguration,
   IObfuscatedPrecomputedConfigurationResponse,
-  ConfigurationWireV1,
+  ConfigurationWireV1, configurationFromString,
 } from '../configuration-wire/configuration-wire-types';
 import { Evaluator, FlagEvaluation } from '../evaluator';
 import {
@@ -137,7 +137,7 @@
     }
 
     describe('bootstrapped client', () => {
-      const banditFlagsConfig = ConfigurationWireV1.fromString(
+      const banditFlagsConfig = configurationFromString(
         readMockConfigurationWireResponse(SHARED_BOOTSTRAP_BANDIT_FLAGS_FILE),
       );
 

src/client/eppo-client.spec.ts

@@ -21,7 +21,7 @@ import { AssignmentCache } from '../cache/abstract-assignment-cache';
 import { IConfigurationStore } from '../configuration-store/configuration-store';
 import { MemoryOnlyConfigurationStore } from '../configuration-store/memory.store';
 import {
-  ConfigurationWireV1,
+  configurationFromString,
   IConfigurationWire,
   IObfuscatedPrecomputedConfigurationResponse,
   ObfuscatedPrecomputedConfigurationResponse,
@@ -321,8 +321,6 @@ describe('EppoClient E2E test', () => {
     });
   });
 
-  const testCases = testCasesByFileName<IAssignmentTestCase>(ASSIGNMENT_TEST_DATA_DIR);
-
   function testCasesAgainstClient(client: EppoClient, testCase: IAssignmentTestCase) {
     const { flag, variationType, defaultValue, subjects } = testCase;
 
@@ -358,10 +356,10 @@ describe('EppoClient E2E test', () => {
     const testCases = testCasesByFileName<IAssignmentTestCase>(ASSIGNMENT_TEST_DATA_DIR);
 
     describe('boostrapped client', () => {
-      const bootstrapFlagsConfig = ConfigurationWireV1.fromString(
+      const bootstrapFlagsConfig = configurationFromString(
         readMockConfigurationWireResponse(SHARED_BOOTSTRAP_FLAGS_FILE),
       );
-      const bootstrapFlagsObfuscatedConfig = ConfigurationWireV1.fromString(
+      const bootstrapFlagsObfuscatedConfig = configurationFromString(
         readMockConfigurationWireResponse(SHARED_BOOTSTRAP_FLAGS_OBFUSCATED_FILE),
       );
 

src/client/eppo-client.ts

@@ -25,10 +25,10 @@ import { MemoryOnlyConfigurationStore } from '../configuration-store/memory.stor
 import {
   ConfigurationWireV1,
   IConfigurationWire,
-  inflateResponse,
   IPrecomputedConfiguration,
   PrecomputedConfiguration,
 } from '../configuration-wire/configuration-wire-types';
+import { inflateJsonObject } from '../configuration-wire/json-util';
 import {
   DEFAULT_INITIAL_CONFIG_REQUEST_RETRIES,
   DEFAULT_POLL_CONFIG_REQUEST_RETRIES,
@@ -348,11 +348,11 @@ export default class EppoClient {
     if (!configuration.config) {
       throw new Error('Flag configuration not provided');
     }
-    const flagConfigResponse: IUniversalFlagConfigResponse = inflateResponse(
+    const flagConfigResponse: IUniversalFlagConfigResponse = inflateJsonObject(
       configuration.config.response,
     );
     const banditParamResponse: IBanditParametersResponse | undefined = configuration.bandits
-      ? inflateResponse(configuration.bandits.response)
+      ? inflateJsonObject(configuration.bandits.response)
       : undefined;
 
     // We need to run this method sync, but, because the configuration stores potentially have an async write at the end

src/configuration-wire/configuration-wire-types.spec.ts

@@ -6,7 +6,8 @@ import {
 import { IUniversalFlagConfigResponse, IBanditParametersResponse } from '../http-client';
 import { FormatEnum } from '../interfaces';
 
-import { ConfigurationWireV1, deflateResponse, inflateResponse } from './configuration-wire-types';
+import { ConfigurationWireV1 } from './configuration-wire-types';
+import { deflateJsonObject, inflateJsonObject } from './json-util';
 
 describe('Response String Type Safety', () => {
   const mockFlagConfig: IUniversalFlagConfigResponse = readMockUFCResponse(
@@ -18,22 +19,22 @@ describe('Response String Type Safety', () => {
 
   describe('deflateResponse and inflateResponse', () => {
     it('should correctly serialize and deserialize flag config', () => {
-      const serialized = deflateResponse(mockFlagConfig);
-      const deserialized = inflateResponse(serialized);
+      const serialized = deflateJsonObject(mockFlagConfig);
+      const deserialized = inflateJsonObject(serialized);
 
       expect(deserialized).toEqual(mockFlagConfig);
     });
 
     it('should correctly serialize and deserialize bandit config', () => {
-      const serialized = deflateResponse(mockBanditConfig);
-      const deserialized = inflateResponse(serialized);
+      const serialized = deflateJsonObject(mockBanditConfig);
+      const deserialized = inflateJsonObject(serialized);
 
       expect(deserialized).toEqual(mockBanditConfig);
     });
 
     it('should maintain type information through serialization', () => {
-      const serialized = deflateResponse(mockFlagConfig);
-      const deserialized = inflateResponse(serialized);
+      const serialized = deflateJsonObject(mockFlagConfig);
+      const deserialized = inflateJsonObject(serialized);
 
       // TypeScript compilation check: these should work
       expect(deserialized.format).toBe(FormatEnum.SERVER);
@@ -54,7 +55,7 @@ describe('Response String Type Safety', () => {
       if (!wirePacket.config) {
         fail('Flag config not present in ConfigurationWire');
       }
-      const deserializedConfig = inflateResponse(wirePacket.config.response);
+      const deserializedConfig = inflateJsonObject(wirePacket.config.response);
       expect(deserializedConfig).toEqual(mockFlagConfig);
     });
 
@@ -80,8 +81,8 @@ describe('Response String Type Safety', () => {
       expect(wirePacket.bandits.etag).toBe('bandit-etag');
 
       // Verify we can deserialize both responses
-      const deserializedConfig = inflateResponse(wirePacket.config.response);
-      const deserializedBandits = inflateResponse(wirePacket.bandits.response);
+      const deserializedConfig = inflateJsonObject(wirePacket.config.response);
+      const deserializedBandits = inflateJsonObject(wirePacket.bandits.response);
 
       expect(deserializedConfig).toEqual(mockFlagConfig);
       expect(deserializedBandits).toEqual(mockBanditConfig);

src/configuration-wire/configuration-wire-types.ts

@@ -1,4 +1,4 @@
-import { IUniversalFlagConfigResponse, IBanditParametersResponse } from '../http-client';
+import { IBanditParametersResponse, IUniversalFlagConfigResponse } from '../http-client';
 import {
   Environment,
   FormatEnum,
@@ -9,6 +9,20 @@ import {
 import { obfuscatePrecomputedBanditMap, obfuscatePrecomputedFlags } from '../obfuscation';
 import { ContextAttributes, FlagKey, HashedFlagKey } from '../types';
 
+import { deflateJsonObject, inflateJsonObject, JsonString } from './json-util';
+
+/**
+ * Builds an `IConfigurationWire` instance from the payload string.
+ * To generate the payload string, see `ConfigurationWireHelper.fetchBootstrapConfiguration`.
+ *
+ * @param payloadString
+ */
+export function configurationFromString(
+  payloadString: string | JsonString<IConfigurationWire>,
+): IConfigurationWire {
+  return inflateJsonObject(payloadString as JsonString<IConfigurationWire>);
+}
+
 // Base interface for all configuration responses
 interface IBasePrecomputedConfigurationResponse {
   readonly format: FormatEnum.PRECOMPUTED;
@@ -169,28 +183,17 @@ export interface IConfigurationWire {
 type UfcResponseType = IUniversalFlagConfigResponse | IBanditParametersResponse;
 
 // The UFC responses are JSON-encoded strings so we can treat them as opaque blobs, but we also want to enforce type safety.
-type ResponseString<T extends UfcResponseType> = string & {
-  readonly __brand: unique symbol;
-  readonly __type: T;
-};
+type UFCResponseString<T extends UfcResponseType> = JsonString<T>;
 
 /**
  * A wrapper around a server response that includes the response, etag, and fetchedAt timestamp.
  */
 interface IConfigResponse<T extends UfcResponseType> {
-  readonly response: ResponseString<T>; // JSON-encoded server response
+  readonly response: UFCResponseString<T>; // JSON-encoded server response
   readonly etag?: string; // Entity Tag - denotes a snapshot or version of the config.
   readonly fetchedAt?: string; // ISO timestamp for when this config was fetched
 }
 
-export function inflateResponse<T extends UfcResponseType>(response: ResponseString<T>): T {
-  return JSON.parse(response) as T;
-}
-
-export function deflateResponse<T extends UfcResponseType>(value: T): ResponseString<T> {
-  return JSON.stringify(value) as ResponseString<T>;
-}
-
 export class ConfigurationWireV1 implements IConfigurationWire {
   public readonly version = 1;
 
@@ -200,10 +203,6 @@ export class ConfigurationWireV1 implements IConfigurationWire {
     readonly bandits?: IConfigResponse<IBanditParametersResponse>,
   ) {}
 
-  public static fromString(stringifiedPayload: string): IConfigurationWire {
-    return JSON.parse(stringifiedPayload) as IConfigurationWire;
-  }
-
   public static fromResponses(
     flagConfig: IUniversalFlagConfigResponse,
     banditConfig?: IBanditParametersResponse,
@@ -213,13 +212,13 @@ export class ConfigurationWireV1 implements IConfigurationWire {
     return new ConfigurationWireV1(
       undefined,
       {
-        response: deflateResponse(flagConfig),
+        response: deflateJsonObject(flagConfig),
         fetchedAt: new Date().toISOString(),
         etag: flagConfigEtag,
       },
       banditConfig
         ? {
-            response: deflateResponse(banditConfig),
+            response: deflateJsonObject(banditConfig),
             fetchedAt: new Date().toISOString(),
             etag: banditConfigEtag,
           }

src/configuration-wire/json-util.ts

@@ -0,0 +1,12 @@
+export type JsonString<T> = string & {
+  readonly __brand: unique symbol;
+  readonly __type: T;
+};
+
+export function inflateJsonObject<T>(response: JsonString<T>): T {
+  return JSON.parse(response) as T;
+}
+
+export function deflateJsonObject<T>(value: T): JsonString<T> {
+  return JSON.stringify(value) as JsonString<T>;
+}

src/index.ts

@@ -36,6 +36,7 @@ import { ConfigurationStoreBundle } from './configuration-store/i-configuration-
 import { MemoryStore, MemoryOnlyConfigurationStore } from './configuration-store/memory.store';
 import { ConfigurationWireHelper } from './configuration-wire/configuration-wire-helper';
 import {
+  configurationFromString,
   IConfigurationWire,
   IObfuscatedPrecomputedConfigurationResponse,
   IPrecomputedConfigurationResponse,
@@ -159,6 +160,7 @@ export {
   PrecomputedFlag,
   FlagKey,
   ConfigurationWireHelper,
+  configurationFromString,
 
   // Test helpers
   decodePrecomputedFlag,