Implement isExactly validator

Author: AJCStriker

package.json

@@ -1,6 +1,6 @@
 {
   "name": "strontium",
-  "version": "2.3.4",
+  "version": "2.3.5",
   "description": "Strontium is a TypeScript toolkit for High Performance API servers built for Production not Projects.",
   "main": "lib/src/index.js",
   "types": "lib/src/index.d.ts",

src/validation/drivers/validators/isExactly.ts

@@ -0,0 +1,19 @@
+import { ValidationError } from "../../../errors"
+
+export const isExactly = <V extends Array<O>, O>(values: V) => (
+    i: unknown
+): O => {
+    for (let value of values) {
+        if (value === i) {
+            return value
+        }
+    }
+
+    throw new ValidationError(
+        "IS_EXACTLY",
+        "Value not in permitted set",
+        `The provided value was not allowed for this field. Allowed values are: '${values.join(
+            "', '"
+        )}'`
+    )
+}

tests/validation/drivers/validators/isExactly.spec.ts

@@ -0,0 +1,26 @@
+import { expectToThrowCustomClass } from "../../../helpers/ExpectToThrowCustomClass"
+import { expect } from "chai"
+import { isExactly } from "../../../../src/validation/drivers/validators/isExactly"
+import { ValidationError, isBoolean } from "../../../../src"
+
+describe("isExactly", () => {
+    it("should return the input if the input is included in the allowed set", () => {
+        let testValidator = isExactly(["test", "other-test", "more-test"])
+
+        expect(testValidator("other-test")).to.equal("other-test")
+        expect(testValidator("test")).to.equal("test")
+        expect(testValidator("more-test")).to.equal("more-test")
+    })
+
+    it("should return a validation error if input is not boolean", () => {
+        let testValidator = isExactly(["test", "other-test", "more-test"])
+
+        expectToThrowCustomClass(() => testValidator({}), ValidationError)
+        expectToThrowCustomClass(() => testValidator(1), ValidationError)
+        expectToThrowCustomClass(() => testValidator(0), ValidationError)
+        expectToThrowCustomClass(() => testValidator("das"), ValidationError)
+        expectToThrowCustomClass(() => testValidator("true"), ValidationError)
+        expectToThrowCustomClass(() => testValidator(false), ValidationError)
+        expectToThrowCustomClass(() => testValidator([]), ValidationError)
+    })
+})