feat: add resultToPromise transformer (#170)

Author: patrickmichalina

src/result/pubcli_api.spec.ts

@@ -1,9 +1,10 @@
-import { Result, fail, ok, result } from './public_api'
+import { Result, fail, ok, result, resultToPromise } from './public_api'
 
 describe('result api', () => {
   it('should export', () => {
     expect(fail(Error('Test'))).toBeInstanceOf(Result)
     expect(ok(1)).toBeInstanceOf(Result)
     expect(result(() => true, 1, Error('Test'))).toBeInstanceOf(Result)
+    expect(typeof resultToPromise).toEqual('function')
   })
 })

src/result/public_api.ts

@@ -1,3 +1,4 @@
 export * from './result'
 export * from './result.factory'
 export * from './result.interface'
+export * from './transformers/result-to-promise'

src/result/transformers/result-to-promise.spec.ts

@@ -0,0 +1,24 @@
+import { fail, ok } from '../result.factory'
+import { IResult } from '../result.interface'
+import { resultToPromise } from './result-to-promise'
+
+describe('resultToPromise', () => {
+  it('should map', () => {
+    const sut = new Promise<IResult<string, Error>>(resolve => resolve(ok('test')))
+
+    return sut
+      .then(resultToPromise)
+      .then(result => expect(result).toEqual('test'))
+      .catch(() => expect(false).toBe(true))
+  })
+
+  it('should catch w/ fail result', () => {
+    const sut = new Promise<IResult<string, Error>>(resolve => resolve(fail(new Error('test error'))))
+
+    return sut
+      .then(resultToPromise)
+      .then(() => expect(false).toBe(true))
+      .catch(error => expect(error).toEqual(new Error('test error')))
+  })
+
+})

src/result/transformers/result-to-promise.ts

@@ -0,0 +1,6 @@
+import { IResult } from '../result.interface'
+
+export const resultToPromise =
+  <TOk, TFail>(result: IResult<TOk, TFail>): Promise<TOk> => result.isOk()
+    ? Promise.resolve(result.unwrap() as TOk)
+    : Promise.reject(result.unwrapFail() as TFail)