feat(helpers)!: use const generics where possible (#2685)

1 files changed, 127 insertions, 0 deletions

diff --git a/test/modules/helpers.spec-d.ts b/test/modules/helpers.spec-d.ts
new file mode 100644
index 00000000..11ce8c88
--- /dev/null
+++ b/test/modules/helpers.spec-d.ts
@@ -0,0 +1,127 @@
+import { describe, expectTypeOf, it } from 'vitest';
+import { faker } from '../../src';
+
+describe('helpers', () => {
+  describe('shuffle', () => {
+    describe('inplace: true', () => {
+      it('const generic single element', () => {
+        const actual = faker.helpers.shuffle([1], { inplace: true });
+        expectTypeOf(actual).toEqualTypeOf<Array<1>>();
+      });
+
+      it('const generic multiple elements', () => {
+        const actual = faker.helpers.shuffle([1, 'a', false], {
+          inplace: true,
+        });
+        expectTypeOf(actual).toEqualTypeOf<Array<1 | 'a' | false>>();
+      });
+    });
+
+    describe('inplace: false', () => {
+      it('const generic single element', () => {
+        const actual = faker.helpers.shuffle([1], { inplace: false });
+        expectTypeOf(actual).toEqualTypeOf<Array<1>>();
+      });
+
+      it('const generic multiple elements', () => {
+        const actual = faker.helpers.shuffle([1, 'a', false], {
+          inplace: false,
+        });
+        expectTypeOf(actual).toEqualTypeOf<Array<1 | 'a' | false>>();
+      });
+    });
+  });
+
+  describe('uniqueArray', () => {
+    it('const generic single element', () => {
+      const actual = faker.helpers.uniqueArray([1], 1);
+      expectTypeOf(actual).toEqualTypeOf<Array<1>>();
+    });
+
+    it('const generic multiple elements', () => {
+      const actual = faker.helpers.uniqueArray([1, 'a', false], 3);
+      expectTypeOf(actual).toEqualTypeOf<Array<1 | 'a' | false>>();
+    });
+  });
+
+  describe('maybe', () => {
+    it('const generic single element', () => {
+      // TODO @ST-DDT 2024-02-25: Check why this is detected as `number` instead of `1`
+      const actual = faker.helpers.maybe(() => 1);
+      expectTypeOf(actual).toEqualTypeOf<number | undefined>();
+    });
+  });
+
+  describe('objectKey', () => {
+    it('const generic single element', () => {
+      const actual = faker.helpers.objectKey({ a: 1 });
+      expectTypeOf(actual).toEqualTypeOf<'a'>();
+    });
+
+    it('const generic multiple elements', () => {
+      const actual = faker.helpers.objectKey({ a: 1, b: 'a', c: false });
+      expectTypeOf(actual).toEqualTypeOf<'a' | 'b' | 'c'>();
+    });
+  });
+
+  describe('objectValue', () => {
+    it('const generic single element', () => {
+      const actual = faker.helpers.objectValue({ a: 1 });
+      expectTypeOf(actual).toEqualTypeOf<1>();
+    });
+
+    it('const generic multiple elements', () => {
+      const actual = faker.helpers.objectValue({ a: 1, b: 'a', c: false });
+      expectTypeOf(actual).toEqualTypeOf<1 | 'a' | false>();
+    });
+  });
+
+  describe('objectEntry', () => {
+    it('const generic single element', () => {
+      const actual = faker.helpers.objectEntry({ a: 1 });
+      expectTypeOf(actual).toEqualTypeOf<['a', 1]>();
+    });
+
+    it('const generic multiple elements', () => {
+      const actual = faker.helpers.objectEntry({ a: 1, b: 'a', c: false });
+      // TODO @ST-DDT 2024-02-25: Check whether we can infer the return type any better
+      expectTypeOf(actual).toEqualTypeOf<['a' | 'b' | 'c', false | 1 | 'a']>();
+    });
+  });
+
+  describe('arrayElement', () => {
+    it('const generic single element', () => {
+      const actual = faker.helpers.arrayElement([1]);
+      expectTypeOf(actual).toEqualTypeOf<1>();
+    });
+
+    it('const generic multiple elements', () => {
+      const actual = faker.helpers.arrayElement([1, 'a', false]);
+      expectTypeOf(actual).toEqualTypeOf<1 | 'a' | false>();
+    });
+  });
+
+  describe('arrayElements', () => {
+    it('const generic single element', () => {
+      const actual = faker.helpers.arrayElements([1], 1);
+      expectTypeOf(actual).toEqualTypeOf<Array<1>>();
+    });
+
+    it('const generic multiple elements', () => {
+      const actual = faker.helpers.arrayElements([1, 'a', false], 3);
+      expectTypeOf(actual).toEqualTypeOf<Array<1 | 'a' | false>>();
+    });
+  });
+
+  describe('multiple', () => {
+    it('const generic single element', () => {
+      const actual = faker.helpers.multiple(() => 1);
+      expectTypeOf(actual).toEqualTypeOf<number[]>();
+    });
+
+    it('const generic multiple elements', () => {
+      const actual = faker.helpers.multiple(() => 1, { count: 3 });
+      expectTypeOf(actual).toEqualTypeOf<number[]>();
+    });
+  });
+});