test: Add Option.test

tests/Option.test.ts

@@ -0,0 +1,95 @@
+import { describe } from 'vitest';
+
+import { None, Some, Option } from '../src/main';
+
+const Expected = 'Expected';
+const Wrong = 'Wrong';
+
+describe('Option', () => {
+  describe('Some', it => {
+    it('should expose correct property values', ({ expect }) => {
+      const res = Some(Expected);
+      expect(res.isSome).to.be.true;
+      expect(res.isNone).to.be.false;
+      expect(res.some).to.equal(Expected);
+      expect(
+        //@ts-expect-error
+        res.none
+      ).to.equal(undefined);
+    });
+
+    it('.andThen should replace Some', ({ expect }) => {
+      const before = Some(Expected) as Option<string>;
+      const after = before.andThen(() => Some(Wrong));
+      expect(after.isSome ? after.some : expect.fail()).to.equal(Wrong);
+    });
+
+    it('.elseThen should preserve Some', ({ expect }) => {
+      const before = Some(Expected) as Option<string>;
+      const after = before.elseThen(() => Some(Wrong));
+      expect(after.isSome ? after.some : expect.fail()).to.equal(Expected);
+    });
+
+    it('.match should extract inner value of Some', ({ expect }) => {
+      const before = Some(Expected) as Option<string>;
+      const after = before.match({
+        Some: it => it,
+        None: () => Wrong,
+      });
+      expect(after).to.equal(Expected);
+    });
+
+    it('.intoResult should be Ok', ({ expect }) => {
+      const before = Some(Expected) as Option<string>;
+      const after = before.intoResult(Wrong);
+      expect(after.isOk ? after.ok : expect.fail()).to.equal(Expected);
+    });
+
+    it('.toString should return a string', ({ expect }) => {
+      expect(Some(Expected).toString()).toBeTypeOf('string');
+    });
+  });
+
+  describe('None', it => {
+    it('should expose correct property values', ({ expect }) => {
+      const res = None;
+      expect(res.isSome).to.be.false;
+      expect(res.isNone).to.be.true;
+      expect(
+        //@ts-expect-error
+        res.Some
+      ).to.equal(undefined);
+    });
+
+    it('.andThen should preserve None', ({ expect }) => {
+      const before = None as Option<string>;
+      const after = before.andThen(() => Expected);
+      expect(after).to.equal(None);
+    });
+
+    it('.elseThen should replace None', ({ expect }) => {
+      const before = None as Option<string>;
+      const after = before.elseThen(() => Expected);
+      expect(after).to.equal(Expected);
+    });
+
+    it('.match should extract inner value of None', ({ expect }) => {
+      const before = None as Option<string>;
+      const after = before.match({
+        None: () => Expected,
+        Some: () => Wrong,
+      });
+      expect(after).to.equal(Expected);
+    });
+
+    it('.intoOption should be None', ({ expect }) => {
+      const before = None as Option<string>;
+      const after = before.intoResult(Expected);
+      expect(after.isErr ? after.err : expect.fail()).to.equal(Expected);
+    });
+
+    it('.toString should return a string', ({ expect }) => {
+      expect(None.toString()).toBeTypeOf('string');
+    });
+  });
+});