feat: add catchResult<TValue, TError>() (#192)

Author: patrickmichalina

src/result/public_api.ts

@@ -2,3 +2,4 @@ export * from './result'
 export * from './result.factory'
 export * from './result.interface'
 export * from './transformers/result-to-promise'
+export * from './transformers/try-catch-to-result'

src/result/transformers/try-catch-to-result.spec.ts

@@ -0,0 +1,53 @@
+import { catchResult } from './try-catch-to-result'
+
+describe(catchResult.name, () => {
+  it('should try', done => {
+    function someThrowable(): string {
+      return 'I worked!'
+    }
+
+    const sut = catchResult(someThrowable)
+
+    expect(sut.isOk()).toEqual(true)
+    expect(sut.unwrap()).toEqual('I worked!')
+
+    done()
+  })
+
+  it('should catch', done => {
+    function someThrowable(): string {
+      throw new Error('I failed!')
+    }
+
+    const sut = catchResult(someThrowable)
+
+    expect(sut.isFail()).toEqual(true)
+
+    done()
+  })
+
+  it('should catch with error mapping function', done => {
+    function someThrowable(): string {
+      throw new Error('I failed!')
+    }
+
+    class CustomError extends Error {
+      static fromUnknown(err: unknown): CustomError {
+        if (err instanceof Error) {
+          return new CustomError(err.message)
+        }
+        return new CustomError('new error')
+      }
+      constructor(message?: string) {
+        super(message)
+      }
+    }
+
+    const sut = catchResult(someThrowable, CustomError.fromUnknown)
+
+    expect(sut.isFail()).toEqual(true)
+    expect(sut.unwrapFail().message).toEqual('I failed!')
+
+    done()
+  })
+})

src/result/transformers/try-catch-to-result.ts

@@ -0,0 +1,16 @@
+import { fail, ok } from '../result.factory'
+import { IResult } from '../result.interface'
+
+/**
+ * Ingest a try-catch throwable function so that it doesn't halt the program but instead 
+ * returns an IResult
+ * @param fn a throwable function
+ * @returns an IResult object which wraps the execution as either fail or success
+ */
+export function catchResult<TValue, TError>(fn: () => TValue, errFn?: (err: unknown) => TError): IResult<TValue, TError> {
+  try {
+    return ok<TValue, TError>(fn())
+  } catch(err) {
+    return fail<TValue, TError>(errFn ? errFn(err) : err as TError)
+  }
+}