Pierre Havelaar: Frontend & Backend Technical Assesment

.gitignore

@@ -11,7 +11,7 @@ src/types/api.ts
 /out/
 *.log
 .*
-.yarn/*
+**/.yarn/*
 
 *.log
 .*

backend/.yarnrc.yml

@@ -0,0 +1 @@
+nodeLinker: node-modules

backend/codegen.yml

@@ -17,3 +17,4 @@ generates:
         ID: 'string | number'
       useTypeImports: true
       mappers:
+      immutableTypes: true

backend/package.json

@@ -9,7 +9,8 @@
     "build": "tsc --project ./",
     "lint": "eslint --fix src . && prettier --write src . && tsc --noEmit && format-graphql --write true src/schema/schema.graphql",
     "generate-types": "graphql-codegen",
-    "migrate": "ts-node ./src/bin/migrate.ts"
+    "migrate": "ts-node ./src/bin/migrate.ts",
+    "testdata": "ts-node ./src/bin/testdata.ts"
   },
   "devDependencies": {
     "@graphql-codegen/cli": "1.21.2",
@@ -39,6 +40,7 @@
     "got": "^11.8.5",
     "graphql": "^15.4.0",
     "graphql-import": "^1.0.2",
+    "graphql-scalars": "^1.21.3",
     "graphql-tools": "^7.0.2",
     "roarr": "^3.2.0",
     "slonik": "^23.5.1",

backend/src/bin/migrations/2023.03.30T19.11.25.feature_flag.sql

@@ -0,0 +1,10 @@
+CREATE TYPE feature_flag_type AS ENUM ('boolean', 'string', 'JSON');
+
+CREATE TABLE feature_flag (
+    id integer PRIMARY KEY GENERATED ALWAYS AS IDENTITY,
+    name text NOT NULL UNIQUE,
+    flag_type feature_flag_type NOT NULL,
+    flag_enabled boolean NOT NULL,
+    created_at timestamp with time zone DEFAULT NOW(),
+    updated_at timestamp with time zone DEFAULT NOW()
+);

backend/src/bin/migrations/2023.03.30T19.57.13.feature_flag_variant.sql

@@ -0,0 +1,13 @@
+CREATE TABLE feature_flag_variant (
+    id integer PRIMARY KEY GENERATED ALWAYS AS IDENTITY,
+    feature_flag_id integer NOT NULL,
+    flag_value text NOT NULL,
+    created_at timestamp with time zone DEFAULT NOW(),
+    updated_at timestamp with time zone DEFAULT NOW(),
+    UNIQUE(feature_flag_id, flag_value),
+    CONSTRAINT fk_feature_flag
+        FOREIGN KEY(feature_flag_id)
+            REFERENCES feature_flag(id)
+            ON DELETE CASCADE
+);
+

backend/src/bin/migrations/2023.03.31T11.11.45.context.sql

@@ -0,0 +1,13 @@
+CREATE TABLE context(
+    id integer PRIMARY KEY GENERATED ALWAYS AS IDENTITY,
+    feature_flag_variant_id integer,
+    environment text NOT NULL,
+    context_enabled boolean NOT NULL,
+    created_at timestamp with time zone DEFAULT NOW(),
+    updated_at timestamp with time zone DEFAULT NOW(),
+    UNIQUE(feature_flag_variant_id, environment),
+    CONSTRAINT fk_feature_flag_variant
+        FOREIGN KEY(feature_flag_variant_id)
+            REFERENCES feature_flag_variant(id)
+            ON DELETE CASCADE
+);

backend/src/bin/migrations/2023.03.31T11.31.56.user_context.sql

@@ -0,0 +1,16 @@
+CREATE TABLE user_context (
+    id integer PRIMARY KEY GENERATED ALWAYS AS IDENTITY,
+    user_id integer NOT NULL,
+    context_id integer NOT NULL,
+    created_at timestamp with time zone DEFAULT NOW(),
+    updated_at timestamp with time zone DEFAULT NOW(),
+    UNIQUE(user_id, context_id),
+    CONSTRAINT fk_user
+        FOREIGN KEY(user_id)
+            REFERENCES user_account(id)
+            ON DELETE CASCADE,
+    CONSTRAINT fk_context
+        FOREIGN KEY(context_id)
+            REFERENCES context(id)
+            ON DELETE CASCADE
+);

backend/src/bin/migrations/down/2022.06.29T05.05.57.user_account.sql

@@ -1 +1 @@
-raise 'down migration not implemented'
+DROP TABLE IF EXISTS user_account;

backend/src/bin/migrations/down/2023.03.30T19.11.25.feature_flag.sql

@@ -0,0 +1,2 @@
+DROP TABLE IF EXISTS feature_flag;
+DROP TYPE IF EXISTS feature_flag_type;

backend/src/bin/migrations/down/2023.03.30T19.57.13.feature_flag_variant.sql

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS feature_flag_variant;

backend/src/bin/migrations/down/2023.03.31T11.11.45.context.sql

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS context;

backend/src/bin/migrations/down/2023.03.31T11.31.56.user_context.sql

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS user_context;

backend/src/bin/testdata.ts

@@ -0,0 +1,19 @@
+import { SlonikMigrator } from '@slonik/migrator';
+import { createPool } from 'slonik';
+
+if (!process.env.POSTGRES_CONNECTION_STRING) {
+  throw new Error(
+    'Must provide a PG connection string (export POSTGRES_CONNECTION_STRING=value) -- if you need a fresh database, we recommend using Render.com',
+  );
+}
+
+const slonik = createPool(process.env.POSTGRES_CONNECTION_STRING);
+
+const migrator = new SlonikMigrator({
+  logger: console,
+  migrationsPath: __dirname + '/testdata',
+  migrationTableName: 'testdata',
+  slonik,
+});
+
+migrator.runAsCLI();

backend/src/bin/testdata/2023.03.31T11.40.47.users.sql

@@ -0,0 +1,4 @@
+INSERT INTO user_account (given_name, family_name, email_address)
+VALUES
+    ('Pierre', 'Havelaar', '[email protected]'),
+    ('John', 'Doe', '[email protected]')

backend/src/bin/testdata/2023.03.31T11.46.54.feature_flags.sql

@@ -0,0 +1,6 @@
+INSERT INTO feature_flag (name, flag_type, flag_enabled)
+VALUES
+    ('contra-1', 'boolean', true),
+    ('contra-2', 'boolean', false),
+    ('contra-3', 'string', true),
+    ('contra-4', 'JSON', true)

backend/src/bin/testdata/2023.03.31T11.49.44.feature_flag_variants.sql

@@ -0,0 +1,13 @@
+INSERT INTO feature_flag_variant (feature_flag_id, flag_value)
+VALUES
+    (1, 'true'),
+    (1, 'false'),
+    (2, 'true'),
+    (2, 'false'),
+    (3, 'red'),
+    (3, 'orange'),
+    (3, 'green'),
+    (4, '{ a: true, b: true }'),
+    (4, '{ a: true, b: false }'),
+    (4, '{ a: false, b: true }'),
+    (4, '{ a: false, b: false }')

backend/src/bin/testdata/2023.03.31T11.58.09.contexts.sql

@@ -0,0 +1,24 @@
+INSERT INTO context (feature_flag_variant_id, environment, context_enabled)
+VALUES
+    (1, 'production', false),
+    (1, 'testing', true),
+    (2, 'production', false),
+    (2, 'testing', true),
+    (3, 'production', false),
+    (3, 'testing', true),
+    (4, 'production', false),
+    (4, 'testing', true),
+    (5, 'production', false),
+    (5, 'testing', true),
+    (6, 'production', false),
+    (6, 'testing', true),
+    (7, 'production', false),
+    (7, 'testing', true),
+    (8, 'production', false),
+    (8, 'testing', true),
+    (9, 'production', false),
+    (9, 'testing', true),
+    (10, 'production', false),
+    (10, 'testing', true),
+    (11, 'production', false),
+    (11, 'testing', true)

backend/src/bin/testdata/down/2023.03.31T11.40.47.users.sql

@@ -0,0 +1 @@
+TRUNCATE TABLE user_account RESTART IDENTITY CASCADE;

backend/src/bin/testdata/down/2023.03.31T11.46.54.feature_flags.sql

@@ -0,0 +1 @@
+TRUNCATE TABLE feature_flag RESTART IDENTITY CASCADE;

backend/src/bin/testdata/down/2023.03.31T11.49.44.feature_flag_variants.sql

@@ -0,0 +1 @@
+TRUNCATE TABLE feature_flag_variant RESTART IDENTITY CASCADE;

backend/src/bin/testdata/down/2023.03.31T11.58.09.contexts.sql

@@ -0,0 +1 @@
+TRUNCATE TABLE context RESTART IDENTITY CASCADE;

backend/src/generated/types.ts

@@ -1,26 +1,83 @@
-import type { GraphQLResolveInfo } from 'graphql';
+import type { GraphQLResolveInfo, GraphQLScalarType, GraphQLScalarTypeConfig } from 'graphql';
 import type { ResolverContext } from '../ResolverContextType';
 export type Maybe<T> = T | null | undefined;
 export type Exact<T extends { [key: string]: unknown }> = { [K in keyof T]: T[K] };
 export type MakeOptional<T, K extends keyof T> = Omit<T, K> & { [SubKey in K]?: Maybe<T[SubKey]> };
 export type MakeMaybe<T, K extends keyof T> = Omit<T, K> & { [SubKey in K]: Maybe<T[SubKey]> };
+export type RequireFields<T, K extends keyof T> = { [X in Exclude<keyof T, K>]?: T[X] } & { [P in K]-?: NonNullable<T[P]> };
 /** All built-in and custom scalars, mapped to their actual values */
 export type Scalars = {
   ID: string;
   String: string;
   Boolean: boolean;
   Int: number;
   Float: number;
+  DateTime: any;
+};
+
+
+export enum FlagType {
+  Boolean = 'boolean',
+  String = 'string',
+  Json = 'json'
+}
+
+export type Feature = {
+  readonly __typename?: 'Feature';
+  readonly contextId: Scalars['Int'];
+  readonly name: Scalars['String'];
+  readonly type?: Maybe<FlagType>;
+  readonly value: Scalars['String'];
+};
+
+export type User = {
+  readonly __typename?: 'User';
+  readonly id: Scalars['Int'];
+  readonly givenName: Scalars['String'];
+  readonly familyName: Scalars['String'];
+  readonly emailAddress?: Maybe<Scalars['String']>;
+  readonly createdAt: Scalars['DateTime'];
+  readonly updatedAt: Scalars['DateTime'];
+  readonly environment: Scalars['String'];
+  readonly features: ReadonlyArray<Feature>;
 };
 
 export type Mutation = {
-  __typename?: 'Mutation';
-  sampleMutation: Scalars['String'];
+  readonly __typename?: 'Mutation';
+  /** Setup a feature flag for a group of users. The feature flag and value must already exist. */
+  readonly targetUsers: ReadonlyArray<User>;
+  /**
+   * Update an existing feature flag for a single user.
+   * If the feature is not availabe for this user or is assigned to multiple user an error will be thrown.
+   */
+  readonly updateFeatureForUser?: Maybe<Scalars['Int']>;
+};
+
+
+export type MutationTargetUsersArgs = {
+  userIds: ReadonlyArray<Scalars['Int']>;
+  flag: Scalars['String'];
+  value: Scalars['String'];
+  environment: Scalars['String'];
+};
+
+
+export type MutationUpdateFeatureForUserArgs = {
+  userId: Scalars['Int'];
+  flag: Scalars['String'];
+  value: Scalars['String'];
+  environment: Scalars['String'];
 };
 
 export type Query = {
-  __typename?: 'Query';
-  hello: Scalars['String'];
+  readonly __typename?: 'Query';
+  /** Retrieve all the users in the system and their feature flags for the given environment */
+  readonly users: ReadonlyArray<User>;
+};
+
+
+export type QueryUsersArgs = {
+  environment: Scalars['String'];
 };
 
 export type WithIndex<TObject> = TObject & Record<string, any>;
@@ -89,29 +146,66 @@ export type DirectiveResolverFn<TResult = {}, TParent = {}, TContext = {}, TArgs
 
 /** Mapping between all available schema types and the resolvers types */
 export type ResolversTypes = ResolversObject<{
-  Mutation: ResolverTypeWrapper<{}>;
+  DateTime: ResolverTypeWrapper<Scalars['DateTime']>;
+  FlagType: FlagType;
+  Feature: ResolverTypeWrapper<Feature>;
+  Int: ResolverTypeWrapper<Scalars['Int']>;
   String: ResolverTypeWrapper<Scalars['String']>;
+  User: ResolverTypeWrapper<User>;
+  Mutation: ResolverTypeWrapper<{}>;
   Query: ResolverTypeWrapper<{}>;
   Boolean: ResolverTypeWrapper<Scalars['Boolean']>;
 }>;
 
 /** Mapping between all available schema types and the resolvers parents */
 export type ResolversParentTypes = ResolversObject<{
-  Mutation: {};
+  DateTime: Scalars['DateTime'];
+  Feature: Feature;
+  Int: Scalars['Int'];
   String: Scalars['String'];
+  User: User;
+  Mutation: {};
   Query: {};
   Boolean: Scalars['Boolean'];
 }>;
 
+export interface DateTimeScalarConfig extends GraphQLScalarTypeConfig<ResolversTypes['DateTime'], any> {
+  name: 'DateTime';
+}
+
+export type FeatureResolvers<ContextType = ResolverContext, ParentType = ResolversParentTypes['Feature']> = ResolversObject<{
+  contextId?: Resolver<ResolversTypes['Int'], ParentType, ContextType>;
+  name?: Resolver<ResolversTypes['String'], ParentType, ContextType>;
+  type?: Resolver<Maybe<ResolversTypes['FlagType']>, ParentType, ContextType>;
+  value?: Resolver<ResolversTypes['String'], ParentType, ContextType>;
+  __isTypeOf?: IsTypeOfResolverFn<ParentType, ContextType>;
+}>;
+
+export type UserResolvers<ContextType = ResolverContext, ParentType = ResolversParentTypes['User']> = ResolversObject<{
+  id?: Resolver<ResolversTypes['Int'], ParentType, ContextType>;
+  givenName?: Resolver<ResolversTypes['String'], ParentType, ContextType>;
+  familyName?: Resolver<ResolversTypes['String'], ParentType, ContextType>;
+  emailAddress?: Resolver<Maybe<ResolversTypes['String']>, ParentType, ContextType>;
+  createdAt?: Resolver<ResolversTypes['DateTime'], ParentType, ContextType>;
+  updatedAt?: Resolver<ResolversTypes['DateTime'], ParentType, ContextType>;
+  environment?: Resolver<ResolversTypes['String'], ParentType, ContextType>;
+  features?: Resolver<ReadonlyArray<ResolversTypes['Feature']>, ParentType, ContextType>;
+  __isTypeOf?: IsTypeOfResolverFn<ParentType, ContextType>;
+}>;
+
 export type MutationResolvers<ContextType = ResolverContext, ParentType = ResolversParentTypes['Mutation']> = ResolversObject<{
-  sampleMutation?: Resolver<ResolversTypes['String'], ParentType, ContextType>;
+  targetUsers?: Resolver<ReadonlyArray<ResolversTypes['User']>, ParentType, ContextType, RequireFields<MutationTargetUsersArgs, 'userIds' | 'flag' | 'value' | 'environment'>>;
+  updateFeatureForUser?: Resolver<Maybe<ResolversTypes['Int']>, ParentType, ContextType, RequireFields<MutationUpdateFeatureForUserArgs, 'userId' | 'flag' | 'value' | 'environment'>>;
 }>;
 
 export type QueryResolvers<ContextType = ResolverContext, ParentType = ResolversParentTypes['Query']> = ResolversObject<{
-  hello?: Resolver<ResolversTypes['String'], ParentType, ContextType>;
+  users?: Resolver<ReadonlyArray<ResolversTypes['User']>, ParentType, ContextType, RequireFields<QueryUsersArgs, 'environment'>>;
 }>;
 
 export type Resolvers<ContextType = ResolverContext> = ResolversObject<{
+  DateTime?: GraphQLScalarType;
+  Feature?: FeatureResolvers<ContextType>;
+  User?: UserResolvers<ContextType>;
   Mutation?: MutationResolvers<ContextType>;
   Query?: QueryResolvers<ContextType>;
 }>;

backend/src/schema/resolvers/Mutations/index.ts

@@ -1,5 +1,7 @@
-import { resolve as sampleMutation } from './sampleMutation';
+import { updateFeatureForUser } from './updateFeatureForUser';
+import { targetUsers } from './targetUsers';
 
 export const Mutation = {
-  sampleMutation,
+  targetUsers,
+  updateFeatureForUser,
 };