test(types): add initial typesafety verification testing

Using dtslint to ensure that typesafety guarentees do not have any unintentional changes or
regressions

README.md

@@ -32,60 +32,74 @@ npm install @squirly/di
 import {Binding, Container, Injectable} from '@squirly/di';
 
 const AuthenticationKey = Binding<string>('AuthenticationKey');
-const ReversedKey = Binding<string>('ReversedKey');
+interface Fetcher {
+  fetch: () => Promise<{data: string}>;
+}
+const Fetcher = Binding<Fetcher>('Fetcher');
 
 @Injectable
 class Client {
   static Tag = Binding.Tag<Client>('Client');
-  static Inject = Injectable.Resolution(ReversedKey);
+  static Inject = Injectable.Resolution(Fetcher);
 
-  constructor(private readonly key: string) {}
+  constructor(private readonly fetcher: Fetcher) {}
 
-  getData(): string {
-    return `Calling API with '${this.key}'`;
+  getData(): Promise<string> {
+    return this.fetcher
+      .fetch()
+      .then(result => `Received result: '${result.data}'`);
   }
 }
 
+async function fetcherFactory(c: Container<string>): Promise<Fetcher> {
+  const key = await c.resolve(AuthenticationKey);
+
+  return {
+    fetch: () =>
+      Promise.resolve({
+        data: `Called with AuthenticationKey "${key}"`,
+      }),
+  };
+}
+
 const container = Container.create()
   .bindConstant(AuthenticationKey, 'my-secret-key')
-  .bindSingletonFactory(ReversedKey, async c =>
-    Array.from(await c.resolve(AuthenticationKey))
-      .reverse()
-      .join(''),
-  )
+  .bindSingletonFactory(Fetcher, fetcherFactory)
   .bindService(Client, Client);
 
-container.resolve(Client).then(client => {
-  client.getData(); // returns "Calling API with 'yek-terces-ym'"
-});
+const clientResult = container.resolve(Client).then(client => client.getData());
+
+// Logs 'Received result: Called with AuthenticationKey "my-secret-key"';
+clientResult.then(console.log);
 ```
 
 ### Module
 
 Using the definitions above, a `Module` can be created.
 
 ```typescript
-import {Binding, Container, Injectable} from '@squirly/di';
+import {Module} from '@squirly/di';
 
 const module = Module.create(
   Container.create()
     .bindConstant(AuthenticationKey, 'my-secret-key')
-    .bindSingletonFactory(ReversedKey, async c =>
-      Array.from(await c.resolve(AuthenticationKey))
-        .reverse()
-        .join(''),
-    ),
-).export(ReversedKey);
+    .bindSingletonFactory(Fetcher, fetcherFactory),
+).export(Fetcher);
 
-const container = Container.create()
+const moduleContainer = Container.create()
   .importModule(module)
   .bindService(Client, Client);
 
-container.resolve(Client).then(client => {
-  client.getData() // returns "Calling API with 'yek-terces-ym'"
+moduleContainer.resolve(Client).then(client => {
+  client.getData(); // returns "Calling API with 'yek-terces-ym'"
 });
 
-container.resolve(AuthenticationKey); // Promise rejected with MissingDependencyError('Could not find dependency bound to AuthenticationKey.')
+// $ExpectError
+const resolution = moduleContainer.resolve(AuthenticationKey);
+// Type 'string' is not assignable to 'Fetcher | Client'
+
+// Logs "MissingDependencyError('Could not find dependency bound to AuthenticationKey.')"
+clientResult.catch(console.log);
 ```
 
 ## Maintainers

package.json

@@ -21,8 +21,8 @@
   "types": "lib/index.d.ts",
   "scripts": {
     "check": "run-p commitlint lint build:check test",
-    "lint": "tslint --project .",
-    "lint:fix": "tslint --project . --fix",
+    "lint": "tslint --project . && (cd typeTests && tslint --project .)",
+    "lint:fix": "tslint --project . --fix && (cd typeTests && tslint --project . --fix)",
     "test": "jest --coverage",
     "test:watch": "jest --watch",
     "prebuild": "rm -rf lib",
@@ -39,6 +39,7 @@
     "@types/jest": "23.3.2",
     "commitizen": "2.10.1",
     "cz-conventional-changelog": "2.1.0",
+    "dtslint": "0.3.0",
     "jest": "23.6.0",
     "jest-junit": "5.2.0",
     "npm-run-all": "4.1.3",

tsconfig.json

@@ -11,5 +11,6 @@
     "noImplicitReturns": true,
     "experimentalDecorators": true,
     "types": ["jest"]
-  }
+  },
+  "include": ["src/**/*"]
 }

tslint.json

@@ -2,6 +2,7 @@
   "extends": ["tslint:recommended", "tslint-config-prettier"],
   "rulesDirectory": ["tslint-plugin-prettier"],
   "rules": {
+    "file-name-casing": false,
     "interface-name": false,
     "max-classes-per-file": false,
     "member-access": false,

typeTests/Container.ts

@@ -0,0 +1,28 @@
+import {Binding, Container} from '@squirly/di';
+import {C} from './Dependencies';
+import {
+  Service1,
+  Service2,
+  Service3Invalid,
+  Service4Invalid,
+  Service5,
+  Service6Invalid,
+  Service7,
+  Service8Invalid,
+} from './Injectable';
+
+const binding = Binding<{}>('binding');
+
+const container = Container.create()
+  .bindService(binding, Service1)
+  .bindService(Service2, Service2)
+  // TODO: $ExpectError
+  .bindService(C, Service3Invalid)
+  // TODO: $ExpectError
+  .bindService(binding, Service4Invalid)
+  .bindService(binding, Service5)
+  // TODO: $ExpectError
+  .bindService(binding, Service6Invalid)
+  .bindService(binding, Service7)
+  // TODO: $ExpectError
+  .bindService(binding, Service8Invalid);

typeTests/Dependencies.ts

@@ -0,0 +1,31 @@
+import {Binding} from '@squirly/di';
+
+// Bound types
+
+export type A = string & {_: 'A'};
+export type A0 = string & {_: 'A'; '1': 'A'};
+export const A = Binding<A>('A');
+
+export type B = string & {_: 'B'};
+export const B = Binding<B>('B');
+
+export type C = string & {_: 'C'};
+export const C = Binding<B>('C');
+
+// Injectable values
+
+let a: A = 'a' as A;
+let a0: A0 = 'a0' as A0;
+let b: B = 'b' as B;
+let c: C = 'c' as C;
+
+// Assignability tests
+
+a = a0;
+a = b; // $ExpectError
+a = c; // $ExpectError
+a0 = a; // $ExpectError
+b = a; // $ExpectError
+b = c; // $ExpectError
+c = a; // $ExpectError
+c = b; // $ExpectError