From 8719c5f930b55b33c93dd8e21592938935afec2f Mon Sep 17 00:00:00 2001
From: Alex Regan <alex.joseph.regan@gmail.com>
Date: Tue, 13 Feb 2018 04:22:25 -0700
Subject: [PATCH] feat(result): `expect` impl

---
 src/result.class.ts |  9 +++++++++
 src/result.test.ts  | 10 ++++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/result.class.ts b/src/result.class.ts
index 9c79ac9..dd2584b 100644
--- a/src/result.class.ts
+++ b/src/result.class.ts
@@ -184,6 +184,15 @@ export class Result<T, E> {
     });
   }
 
+  public expect(err_msg: string): T {
+    return this.match({
+      ok: (t: T) => t,
+      err: (_: E) => {
+        throw new Error(err_msg);
+      },
+    });
+  }
+
   public static Ok<T>(val: T): Result<T, any> {
     return new Result(Ok(val));
   }
diff --git a/src/result.test.ts b/src/result.test.ts
index 7555a9b..f46644d 100644
--- a/src/result.test.ts
+++ b/src/result.test.ts
@@ -226,3 +226,13 @@ describe("Result.unwrap", async () => {
     expect(() => Err("error").unwrap()).toThrow(Error);
   });
 });
+
+describe("Result.expect", async () => {
+  it("should not throw with Ok", async () => {
+    expect(Ok(2).expect("my error")).toBe(2);
+  });
+
+  it("should throw with Err", async () => {
+    expect(() => Err("error").expect("my error")).toThrow("my error");
+  });
+});