restore feature flag logic so it can be used in future

utils/__tests__/featureFlag.test.ts

@@ -0,0 +1,74 @@
+import {
+  FeatureFlagEnum,
+  getIsUserEligibleForNewFeature
+} from "../featureFlag";
+import { FiscalCode } from "@pagopa/ts-commons/lib/strings";
+import { aFiscalCode, anotherFiscalCode } from "../../__mocks__/mocks";
+
+const betaUsers: FiscalCode[] = [aFiscalCode];
+const isUserBeta = (fc: FiscalCode) => betaUsers.includes(fc);
+
+describe("isUserForFeatureFlag", () => {
+  it("should return true when featureFlag === all", () => {
+    const isUserForFeatureFlag = getIsUserEligibleForNewFeature(
+      isUserBeta,
+      _ => false,
+      FeatureFlagEnum.ALL
+    );
+    expect(isUserForFeatureFlag(aFiscalCode)).toBeTruthy();
+  });
+
+  it("should return false when featureFlag === beta and the user is not beta", () => {
+    const isUserForFeatureFlag = getIsUserEligibleForNewFeature(
+      isUserBeta,
+      _ => false,
+      FeatureFlagEnum.BETA
+    );
+    expect(isUserForFeatureFlag(anotherFiscalCode)).toBeFalsy();
+  });
+
+  it("should return true when featureFlag === beta and the first callback return true", () => {
+    const isUserForFeatureFlag = getIsUserEligibleForNewFeature(
+      isUserBeta,
+      _ => false,
+      FeatureFlagEnum.BETA
+    );
+    expect(isUserForFeatureFlag(aFiscalCode)).toBeTruthy();
+  });
+
+  it("should return false when featureFlag === canary and callbacks return false", () => {
+    const isUserForFeatureFlag = getIsUserEligibleForNewFeature(
+      isUserBeta,
+      _ => false,
+      FeatureFlagEnum.CANARY
+    );
+    expect(isUserForFeatureFlag(anotherFiscalCode)).toBeFalsy();
+  });
+
+  it("should return true when featureFlag === canary and the first callback return true", () => {
+    const isUserForFeatureFlag = getIsUserEligibleForNewFeature(
+      isUserBeta,
+      _ => false,
+      FeatureFlagEnum.CANARY
+    );
+    expect(isUserForFeatureFlag(aFiscalCode)).toBeTruthy();
+  });
+
+  it("should return true when featureFlag === canary and the second callback return true", () => {
+    const isUserForFeatureFlag = getIsUserEligibleForNewFeature(
+      isUserBeta,
+      _ => true,
+      FeatureFlagEnum.CANARY
+    );
+    expect(isUserForFeatureFlag(anotherFiscalCode)).toBeTruthy();
+  });
+
+  it("should return false when featureFlag === none", () => {
+    const isUserForFeatureFlag = getIsUserEligibleForNewFeature(
+      isUserBeta,
+      _ => true,
+      FeatureFlagEnum.NONE
+    );
+    expect(isUserForFeatureFlag(aFiscalCode)).toBeFalsy();
+  });
+});

utils/config.ts

@@ -25,6 +25,7 @@ import {
 } from "@pagopa/ts-commons/lib/numbers";
 import { flow, pipe } from "fp-ts/lib/function";
 import { CommaSeparatedListOf } from "./comma-separated-list";
+import { FeatureFlag, FeatureFlagEnum } from "./featureFlag";
 
 export const BetaUsers = t.readonlyArray(FiscalCode);
 export type BetaUsers = t.TypeOf<typeof BetaUsers>;
@@ -76,6 +77,8 @@ export const IConfig = t.intersection([
 
     EMAIL_NOTIFICATION_SERVICE_BLACKLIST: CommaSeparatedListOf(ServiceId),
 
+    FEATURE_FLAG: withFallback(FeatureFlag, FeatureFlagEnum.NONE),
+
     WEBHOOK_NOTIFICATION_SERVICE_BLACKLIST: CommaSeparatedListOf(ServiceId),
     // eslint-disable-next-line sort-keys
     IO_FUNCTIONS_ADMIN_API_TOKEN: NonEmptyString,

utils/featureFlag.ts

@@ -0,0 +1,35 @@
+import { enumType } from "@pagopa/ts-commons/lib/types";
+import * as t from "io-ts";
+
+export enum FeatureFlagEnum {
+  ALL = "ALL",
+  BETA = "BETA",
+  CANARY = "CANARY",
+  NONE = "NONE"
+}
+
+export const FeatureFlag = enumType<FeatureFlagEnum>(
+  FeatureFlagEnum,
+  "FeatureFlag"
+);
+
+export type FeatureFlag = t.TypeOf<typeof FeatureFlag>;
+
+export const getIsUserEligibleForNewFeature = <T>(
+  isUserBeta: (i: T) => boolean,
+  isUserCanary: (i: T) => boolean,
+  featureFlag: FeatureFlag
+): ((i: T) => boolean) => (i): boolean => {
+  switch (featureFlag) {
+    case "ALL":
+      return true;
+    case "BETA":
+      return isUserBeta(i);
+    case "CANARY":
+      return isUserCanary(i) || isUserBeta(i);
+    case "NONE":
+      return false;
+    default:
+      return false;
+  }
+};