feat: introduce unwrapResultAsObservable (#194)

Author: patrickmichalina

src/index.spec.ts

@@ -1,4 +1,4 @@
-import { maybe, Maybe, either, Either, ok, fail, Result, reader, Reader, listOf, List } from './index'
+import { maybe, Maybe, either, Either, ok, fail, Result, reader, Reader, listOf, List, unwrapResultAsObservable } from './index'
 
 describe('package api', () => {
   it('should export maybe', () => {
@@ -21,4 +21,8 @@ describe('package api', () => {
   it('should export reader', () => {
     expect(listOf(1, 2)).toBeInstanceOf(List)
   })
+
+  it('should export unwrapResult', () => {
+    expect(unwrapResultAsObservable()).toBeInstanceOf(Function)
+  })
 })

src/result/public_api.ts

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

src/result/result.spec.ts

@@ -156,6 +156,11 @@ describe('result', () => {
       const sut = result(() => 1 + 1 === 2, true, 'FAILURE!')
       expect(sut.isOk()).toEqual(true)
     })
+
+    it('should return fail when predicate yields false', () => {
+      const sut = result(() => 1 + 1 === 1, true, 'FAILURE!')
+      expect(sut.isFail()).toEqual(true)
+    })
   })
 
   describe('toFailIfExists', () => {

src/result/transformers/unwrap-result.spec.ts

@@ -0,0 +1,42 @@
+import { map, of } from 'rxjs'
+import { ok, fail } from '../result.factory'
+import { unwrapResultAsObservable } from './unwrap-result'
+
+describe('unwrapResult', () => {
+  it('should unwrap ok', (done) => {
+    const sut = of(ok<number, string>(1))
+
+    sut.pipe(
+      unwrapResultAsObservable(),
+      map(a => a + 1)
+    ).subscribe({
+      next: v => {
+        expect(v).toEqual(2)
+        done()
+      },
+      error: e => {
+        expect('should not emit from .error').toEqual(false)
+        done(e)
+      }
+    })
+  })
+
+  it('should unwrap fail', done => {
+    const sut = of(fail<number, string>('i failed'))
+
+    sut.pipe(
+      unwrapResultAsObservable(),
+      map(a => a + 2)
+    ).subscribe({
+      error: (v) => {
+        expect(v).toEqual('i failed')
+        done()
+      },
+      next: val => {
+        expect('should not emit from .next').toEqual(false)
+        done(val)
+      }
+    })
+  })
+
+})

src/result/transformers/unwrap-result.ts

@@ -0,0 +1,15 @@
+import { map, Observable } from 'rxjs'
+import { IResult } from '../result.interface'
+
+export function unwrapResultAsObservable<T, E>() {
+  return function unwrapResultAsObservable1(
+    source: Observable<IResult<T, E>>
+  ): Observable<T> {
+    return source.pipe(
+      map(result => {
+        if (result.isOk()) return result.unwrap()
+        throw result.unwrapFail()
+      })
+    ) as Observable<T>
+  }
+}