feat: adds equals and extract methods to Result

Author: richecr

src/result/Result.ts

@@ -7,6 +7,9 @@ export interface Result<T, E> {
   chain<U>(fn: (value: T) => Result<U, E>): Result<U, E>;
   unwrapOr(defaultValue: T): T;
   match<U>(cases: { ok: (value: T) => U; err: (err: E) => U }): U;
+  equals(other: Result<T, E>): boolean;
+
+  extract(): T | E;
 }
 
 export class Ok<T, E> implements Result<T, E> {
@@ -39,6 +42,14 @@ export class Ok<T, E> implements Result<T, E> {
   match<U>(cases: { ok: (value: T) => U; err: (err: E) => U }): U {
     return cases.ok(this.value);
   }
+
+  equals(other: Result<T, E>): boolean {
+    return other.isOk() ? this.value === other.extract() : false;
+  }
+
+  extract(): T {
+    return this.value;
+  }
 }
 
 export class Err<T, E> implements Result<T, E> {
@@ -71,6 +82,14 @@ export class Err<T, E> implements Result<T, E> {
   match<U>(cases: { ok: (value: T) => U; err: (err: E) => U }): U {
     return cases.err(this.error);
   }
+
+  equals(other: Result<T, E>): boolean {
+    return other.isErr() ? this.error === other.extract() : false;
+  }
+
+  extract(): E {
+    return this.error;
+  }
 }
 
 export const fromThrowable = <T, E = unknown>(
@@ -137,3 +156,9 @@ export const matchR = <T, E, U>(
 ) => (result: Result<T, E>): U => {
   return result.match(cases);
 };
+
+export const equalsR = <T, E>(
+  other: Result<T, E>
+) => (result: Result<T, E>): boolean => {
+  return result.equals(other);
+};

tests/result.test.ts

@@ -1,5 +1,6 @@
 import { pipe } from "rambda";
 import { Ok, Err, fromThrowable, fromPromise, fromAsync, matchR, mapR, unwrapOrR, chainR, mapErrR } from "../src/result";
+import { equalsR } from "../src/result/Result";
 
 describe("Result", () => {
   it("Ok.map should apply the function", () => {
@@ -69,6 +70,30 @@ describe("Result", () => {
     expect(result.isErr()).toBe(true);
     expect(result.isOk()).toBe(false);
   });
+
+  it("Ok.equals should be equal to another Ok with same value", () => {
+    const result1 = new Ok(5);
+    const result2 = new Ok(5);
+    expect(result1.equals(result2)).toBe(true);
+  });
+
+  it("Err.equals should be equal to another Err with same error", () => {
+    const result1 = new Err("error");
+    const result2 = new Err("error");
+    expect(result1.equals(result2)).toBe(true);
+  });
+
+  it("Ok.equals should not be equal to Err", () => {
+    const result1 = new Ok(5);
+    const result2 = new Err<number, string>("error");
+    expect(result1.equals(result2)).toBe(false);
+  });
+
+  it("Err.equals should not be equal to Ok", () => {
+    const result1 = new Err("error");
+    const result2 = new Ok<number, string>(5);
+    expect(result1.equals(result2)).toBe(false);
+  });
 });
 
 describe("Result fromThrowable", () => {
@@ -257,4 +282,36 @@ describe("Result - Curried Helpers", () => {
     );
     expect(result).toBe("Error: Something went wrong");
   });
+
+  it("should equals with another Ok using curried equals", () => {
+    const result = pipe(
+      new Ok(5),
+      equalsR(new Ok(5))
+    );
+    expect(result).toBe(true);
+  });
+
+  it("should not equals with another Ok using curried equals", () => {
+    const result = pipe(
+      new Ok(5),
+      equalsR(new Ok(10))
+    );
+    expect(result).toBe(false);
+  });
+
+  it("should equals with another Err using curried equals", () => {
+    const result = pipe(
+      new Err("Error"),
+      equalsR(new Err("Error"))
+    );
+    expect(result).toBe(true);
+  });
+
+  it("should not equals with another Err using curried equals", () => {
+    const result = pipe(
+      new Err("Error"),
+      equalsR(new Err("Different Error"))
+    );
+    expect(result).toBe(false);
+  });
 });