lastIndexOf tests

test/reducers/lastIndexOf.test.ts

@@ -0,0 +1,62 @@
+import { expect } from 'chai';
+import { lastIndexOf } from '../../lib/reducers/lastIndexOf';
+import { fromArray } from '../helpers/asyncGenerators';
+
+describe('reducers/lastIndexOf', () => {
+  describe('When called on empty array', () => {
+    it('Should return -1', async () => {
+      const source = [];
+
+      expect(await lastIndexOf(fromArray(source), () => true)).to.be.equal(-1);
+    });
+  });
+
+  describe('When called on some array', () => {
+    it('Should return the index 3', async () => {
+      const source = [4, 5, 1, 20, 3];
+
+      expect(await lastIndexOf(fromArray(source), elem => elem === 20)).to.be.equal(3);
+    });
+
+    it('Should return the index 2', async () => {
+      const source = [1, 2, 1, 3, 4];
+
+      expect(await lastIndexOf(fromArray(source), elem => elem === 1)).to.be.equal(2);
+    });
+
+    it('Should return -1 if elements does not exist', async () => {
+      const source = ['a', 'b', 'z', 'aa', 'abc'];
+      expect(await lastIndexOf(fromArray(source), elem => elem === 'c')).to.be.equal(-1);
+    });
+  });
+
+  describe('When called with index depending predicate', () => {
+    it('Should return first index', async () => {
+      const source = [1, 4, 3, 2];
+
+      expect(await lastIndexOf(fromArray(source), (elem, idx) => idx === 0)).to.be.equal(0);
+    });
+
+    it('Should return last index', async () => {
+      const source = [1, 4, 3, 2, 5];
+
+      expect(await lastIndexOf(
+        fromArray(source), (elem, idx) => { return idx * 2 === 4; },
+      )).to.be.equal(2);
+    });
+
+    it('Should return last index for multiple matches', async () => {
+      const source = [1, 4, 3, 2, 5];
+
+      expect(await lastIndexOf(
+        fromArray(source), (elem, idx) => { return idx % 2 === 0; }),
+      ).to.be.equal(4);
+    });
+
+    it('Should return the middle index', async () => {
+      const source = [1, 40, 3, 200, 1001];
+
+      expect(await lastIndexOf(fromArray(source), (elem, idx) => idx === 2)).to.be.equal(2);
+    });
+  });
+});