[DSDK-183] [TS] [DSDK] Error/Type safety with purify-ts

packages/core/jest.config.ts

@@ -3,11 +3,15 @@ import type { JestConfigWithTsJest } from "@ledgerhq/jest-config-dsdk";
 const config: JestConfigWithTsJest = {
   preset: "@ledgerhq/jest-config-dsdk",
   setupFiles: ["<rootDir>/jest.setup.ts"],
+  testPathIgnorePatterns: ["<rootDir>/lib/"],
   collectCoverageFrom: [
     // TODO: remove internal when the rest of the files are setup
     "src/internal/**/*.ts",
     "!src/**/*.stub.ts",
   ],
+  moduleNameMapper: {
+    "^@internal/(.*)$": "<rootDir>/src/internal/$1",
+  },
 };
 
 export default config;

packages/core/package.json

@@ -12,13 +12,16 @@
     "dev": "tsc --watch",
     "lint": "eslint --cache --ext .ts \"src\"",
     "lint:fix": "eslint --cache --fix --ext .ts \"src\"",
-    "test:unit": "jest --coverage src",
+    "test": "jest src",
+    "test:watch": "pnpm test -- --watch",
+    "test:coverage": "pnpm test -- --coverage",
     "module:init": "zx scripts/add-module.mjs",
     "run:index": "ts-node src/index.ts"
   },
   "dependencies": {
     "inversify": "^6.0.2",
     "inversify-logger-middleware": "^3.1.0",
+    "purify-ts": "^2.0.3",
     "reflect-metadata": "^0.2.1"
   },
   "devDependencies": {

packages/core/src/di.ts

@@ -12,7 +12,10 @@ export const makeContainer = ({
 }: Partial<MakeContainerProps> = {}) => {
   const container = new Container();
   container.applyMiddleware(logger);
-  container.load(configModuleFactory({ mock }));
+  container.load(
+    configModuleFactory({ mock })
+    // modules go here
+  );
 
   return container;
 };

packages/core/src/index.ts

@@ -1,8 +1,7 @@
 import "reflect-metadata";
-
+import { types } from "@internal/config/di/configTypes";
+import { GetSdkVersionUseCase } from "@internal/config/usecase/GetSdkVersionUseCase";
 import { makeContainer } from "./di";
-import { types } from "./internal/config/di/configTypes";
-import { GetSdkVersionUseCase } from "./internal/config/usecase/GetSdkVersionUseCase";
 
 export * from "./api";
 export * from "./transport";

packages/core/src/internal/config/data/ConfigDataSource.ts

@@ -1,11 +1,16 @@
-import { Config } from "../model/Config";
+import { Either } from "purify-ts";
+import {
+  LocalConfigFailure,
+  RemoteConfigFailure,
+} from "@internal/config/di/configTypes";
+import { Config } from "@internal/config/model/Config";
 
 // Describe the different data sources interfaces our application could have
 
 export interface LocalConfigDataSource {
-  getConfig(): Config;
+  getConfig(): Either<LocalConfigFailure, Config>;
 }
 
 export interface RemoteConfigDataSource {
-  getConfig(): Promise<Config>;
+  getConfig(): Promise<Either<RemoteConfigFailure, Config>>;
 }

packages/core/src/internal/config/data/Dto.ts

@@ -1,6 +1,6 @@
 // Types used by the data sources (here an example for the remote data source)
 // They will usually be the response of an API call that will need to be parsed
-// into an object used by the application. (in our example: DTOConfig => Config)
+// into an object used by the application. (in our example: ConfigDto => Config)
 
 export type ConfigDto = {
   version: string;

packages/core/src/internal/config/data/LocalConfigDataSource.stub.ts

@@ -1,5 +1,6 @@
 import { injectable } from "inversify";
-import { Config } from "../model/Config";
+import { Either } from "purify-ts";
+import { Config } from "@internal/config/model/Config";
 import { LocalConfigDataSource } from "./ConfigDataSource";
 
 /**
@@ -10,10 +11,10 @@ import { LocalConfigDataSource } from "./ConfigDataSource";
 
 @injectable()
 export class StubLocalConfigDataSource implements LocalConfigDataSource {
-  getConfig(): Config {
-    return {
+  getConfig(): Either<never, Config> {
+    return Either.of({
       name: "DeviceSDK",
       version: "0.0.0-mock.1",
-    };
+    });
   }
 }

packages/core/src/internal/config/data/LocalConfigDataSource.test.ts

@@ -1,43 +1,64 @@
 import fs from "fs";
+import { Either, Left } from "purify-ts";
+import { JSONParseError, ReadFileError } from "@internal/config/di/configTypes";
 import { LocalConfigDataSource } from "./ConfigDataSource";
 import { FileLocalConfigDataSource } from "./LocalConfigDataSource";
-import { StubLocalConfigDataSource } from "./LocalConfigDataSource.stub";
 
 const readFileSyncSpy = jest.spyOn(fs, "readFileSync");
+const jsonParse = jest.spyOn(JSON, "parse");
 
 let datasource: LocalConfigDataSource;
 describe("LocalConfigDataSource", () => {
   describe("FileLocalConfigDataSource", () => {
     beforeEach(() => {
       readFileSyncSpy.mockClear();
+      jsonParse.mockClear();
       datasource = new FileLocalConfigDataSource();
+    });
+
+    afterAll(() => {
+      readFileSyncSpy.mockRestore();
+      jsonParse.mockRestore();
+    });
+
+    it("should return an Either<never, Config>", () => {
       readFileSyncSpy.mockReturnValue(
         JSON.stringify({ name: "DeviceSDK", version: "0.0.0-spied.1" })
       );
-    });
 
-    it("should return the config", () => {
-      expect(datasource.getConfig()).toEqual({
+      jsonParse.mockReturnValue({
         name: "DeviceSDK",
         version: "0.0.0-spied.1",
       });
-    });
-  });
 
-  describe("StubLocalConfigDataSource", () => {
-    beforeEach(() => {
-      datasource = new StubLocalConfigDataSource();
+      expect(datasource.getConfig()).toStrictEqual(
+        Either.of({
+          name: "DeviceSDK",
+          version: "0.0.0-spied.1",
+        })
+      );
     });
 
-    it("should return the config", () => {
-      expect(datasource.getConfig()).toEqual({
-        name: "DeviceSDK",
-        version: "0.0.0-mock.1",
+    it("should return an Either<ReadFileError, never> if readFileSync throws", () => {
+      const err = new Error("readFileSync error");
+      readFileSyncSpy.mockImplementation(() => {
+        throw err;
       });
+
+      expect(datasource.getConfig()).toEqual(Left(new ReadFileError(err)));
     });
-  });
 
-  afterAll(() => {
-    readFileSyncSpy.mockClear();
+    it("should return an Either<JSONParseError, never> if JSON.parse throws", () => {
+      const err = new Error("JSON.parse error");
+      readFileSyncSpy.mockReturnValue(
+        JSON.stringify({ name: "DeviceSDK", version: "0.0.0-spied.1" })
+      );
+
+      jsonParse.mockImplementation(() => {
+        throw err;
+      });
+
+      expect(datasource.getConfig()).toEqual(Left(new JSONParseError(err)));
+    });
   });
 });

packages/core/src/internal/config/data/LocalConfigDataSource.ts

@@ -1,8 +1,14 @@
 import fs from "fs";
 import { injectable } from "inversify";
-import { Config } from "../model/Config";
-import { LocalConfigDataSource } from "./ConfigDataSource";
 import path from "path";
+import { Either } from "purify-ts";
+import {
+  ReadFileError,
+  JSONParseError,
+  LocalConfigFailure,
+} from "@internal/config/di/configTypes";
+import { Config } from "@internal/config/model/Config";
+import { LocalConfigDataSource } from "./ConfigDataSource";
 
 /**
  *
@@ -12,11 +18,21 @@ import path from "path";
  */
 @injectable()
 export class FileLocalConfigDataSource implements LocalConfigDataSource {
-  getConfig(): Config {
-    const version = fs.readFileSync(
-      path.join(__dirname, "version.json"),
-      "utf-8"
-    );
-    return JSON.parse(version) as Config;
+  getConfig(): Either<LocalConfigFailure, Config> {
+    return Either.encase(() =>
+      fs.readFileSync(path.join(__dirname, "version.json"), "utf-8")
+    )
+      .mapLeft((error) => {
+        console.log("readFileSync error");
+        return new ReadFileError(error);
+      })
+      .chain((str) => {
+        return Either.encase(() => JSON.parse(str) as Config).mapLeft(
+          (error) => {
+            console.log("JSON.parse error");
+            return new JSONParseError(error);
+          }
+        );
+      });
   }
 }

packages/core/src/internal/config/data/RemoteConfigDataSource.stub.ts

@@ -1,19 +1,22 @@
 import { injectable } from "inversify";
+import { Either } from "purify-ts";
+import { Config } from "@internal/config/model/Config";
 import { RemoteConfigDataSource } from "./ConfigDataSource";
-import { Config } from "../model/Config";
 
 /**
  * class RemoteRestConfigDataSource
  * This is a remote data source that reads the config from a remote API (example).
  */
 @injectable()
 export class StubRemoteConfigDataSource implements RemoteConfigDataSource {
-  async getConfig(): Promise<Config> {
+  async getConfig(): Promise<Either<never, Config>> {
     return new Promise((res) =>
-      res({
-        name: "DeviceSDK",
-        version: "0.0.0-fake.2",
-      })
+      res(
+        Either.of({
+          name: "DeviceSDK",
+          version: "0.0.0-fake.2",
+        })
+      )
     );
   }
 }