address comments

Signed-off-by: Adam Wootton <[email protected]>

Author: ajwootto

libs/providers/multi-provider/src/lib/errors.ts

@@ -1,5 +1,4 @@
 import { ErrorCode, GeneralError, OpenFeatureError } from '@openfeature/server-sdk';
-import { PromiseAllSettledResult } from '@opentelemetry/sdk-metrics/build/esnext/utils';
 import { RegisteredProvider } from './types';
 
 export class ErrorWithCode extends OpenFeatureError {
@@ -35,7 +34,7 @@ export const constructAggregateError = (providerErrors: { error: unknown; provid
 };
 
 export const throwAggregateErrorFromPromiseResults = (
-  result: PromiseAllSettledResult<unknown>[],
+  result: PromiseSettledResult<unknown>[],
   providerEntries: RegisteredProvider[],
 ) => {
   const errors = result

libs/providers/multi-provider/src/lib/strategies/BaseEvaluationStrategy.ts

@@ -1,4 +1,5 @@
 import {
+  ErrorCode,
   EvaluationContext,
   FlagValue,
   FlagValueType,
@@ -77,7 +78,11 @@ export abstract class BaseEvaluationStrategy {
     resolutions: ProviderResolutionResult<T>[],
   ): FinalResult<T>;
 
-  protected hasError(resolution: ProviderResolutionResult<FlagValue>): boolean {
+  protected hasError(resolution: ProviderResolutionResult<FlagValue>): resolution is
+    | ProviderResolutionErrorResult
+    | (ProviderResolutionSuccessResult<FlagValue> & {
+        details: ResolutionDetails<FlagValue> & { errorCode: ErrorCode };
+      }) {
     return 'thrownError' in resolution || !!resolution.details.errorCode;
   }
 

libs/providers/multi-provider/src/lib/strategies/ComparisonStrategy.ts

@@ -5,7 +5,7 @@ import {
   ProviderResolutionSuccessResult,
   StrategyPerProviderContext,
 } from './BaseEvaluationStrategy';
-import { EvaluationContext, FlagValue, Provider } from '@openfeature/server-sdk';
+import { EvaluationContext, FlagValue, GeneralError, Provider } from '@openfeature/server-sdk';
 
 /**
  * Evaluate all providers in parallel and compare the results.
@@ -26,33 +26,45 @@ export class ComparisonStrategy extends BaseEvaluationStrategy {
   override determineFinalResult<T extends FlagValue>(
     strategyContext: StrategyPerProviderContext,
     context: EvaluationContext,
-    resolutions: ProviderResolutionSuccessResult<T>[],
+    resolutions: ProviderResolutionResult<T>[],
   ): FinalResult<T> {
     let value: T | undefined;
     let fallbackResolution: ProviderResolutionSuccessResult<T> | undefined;
+    let finalResolution: ProviderResolutionSuccessResult<T> | undefined;
     let mismatch = false;
-    for (const resolution of resolutions) {
-      if ('thrownError' in resolution || resolution.details.errorCode) {
+    for (const [i, resolution] of resolutions.entries()) {
+      if (this.hasError(resolution)) {
         return this.collectProviderErrors(resolutions);
       }
       if (resolution.provider === this.fallbackProvider) {
         fallbackResolution = resolution;
       }
+      if (i === 0) {
+        finalResolution = resolution;
+      }
       if (typeof value !== 'undefined' && value !== resolution.details.value) {
         mismatch = true;
       } else {
         value = resolution.details.value;
       }
     }
 
+    if (!fallbackResolution) {
+      throw new GeneralError('Fallback provider not found in resolution results');
+    }
+
+    if (!finalResolution) {
+      throw new GeneralError('Final resolution not found in resolution results');
+    }
+
     if (mismatch) {
       this.onMismatch?.(resolutions);
       return {
-        details: fallbackResolution!.details,
-        provider: fallbackResolution!.provider,
+        details: fallbackResolution.details,
+        provider: fallbackResolution.provider,
       };
     }
 
-    return this.resolutionToFinalResult(resolutions[0]);
+    return this.resolutionToFinalResult(finalResolution);
   }
 }

libs/providers/multi-provider/src/lib/strategies/FirstMatchStrategy.ts

@@ -32,7 +32,7 @@ export class FirstMatchStrategy extends BaseEvaluationStrategy {
     resolutions: ProviderResolutionResult<T>[],
   ): FinalResult<T> {
     const finalResolution = resolutions[resolutions.length - 1];
-    if ('thrownError' in finalResolution || !!finalResolution.details.errorCode) {
+    if (this.hasError(finalResolution)) {
       return this.collectProviderErrors(resolutions);
     }
     return this.resolutionToFinalResult(finalResolution);

libs/providers/multi-provider/src/lib/strategies/FirstSuccessfulStrategy.ts

@@ -28,7 +28,7 @@ export class FirstSuccessfulStrategy extends BaseEvaluationStrategy {
     resolutions: ProviderResolutionResult<T>[],
   ): FinalResult<T> {
     const finalResolution = resolutions[resolutions.length - 1];
-    if ('thrownError' in finalResolution || !!finalResolution.details.errorCode) {
+    if (this.hasError(finalResolution)) {
       return this.collectProviderErrors(resolutions);
     }
     return this.resolutionToFinalResult(finalResolution);