From 82c63b467615c0e799c4bb9d4bd1d35c5ac2ca1e Mon Sep 17 00:00:00 2001
From: Lexus Drumgold <unicornware@flexdevelopment.llc>
Date: Thu, 16 Feb 2023 20:40:46 -0500
Subject: [PATCH] feat(internal): `validateMap`

Signed-off-by: Lexus Drumgold <unicornware@flexdevelopment.llc>
---
 src/internal/__tests__/validate-map.spec-d.ts | 16 +++++++++
 src/internal/__tests__/validate-map.spec.ts   | 36 +++++++++++++++++++
 src/internal/validate-map.ts                  | 33 +++++++++++++++++
 3 files changed, 85 insertions(+)
 create mode 100644 src/internal/__tests__/validate-map.spec-d.ts
 create mode 100644 src/internal/__tests__/validate-map.spec.ts
 create mode 100644 src/internal/validate-map.ts

diff --git a/src/internal/__tests__/validate-map.spec-d.ts b/src/internal/__tests__/validate-map.spec-d.ts
new file mode 100644
index 00000000..75dfcf87
--- /dev/null
+++ b/src/internal/__tests__/validate-map.spec-d.ts
@@ -0,0 +1,16 @@
+/**
+ * @file Type Tests - validateMap
+ * @module mlly/internal/tests/unit-d/validateMap
+ */
+
+import type testSubject from '../validate-map'
+
+describe('unit-d:internal/validateMap', () => {
+  it('should guard Map<K, V>', () => {
+    // Arrange
+    type Expected = Map<string, unknown>
+
+    // Expect
+    expectTypeOf<typeof testSubject>().guards.toEqualTypeOf<Expected>()
+  })
+})
diff --git a/src/internal/__tests__/validate-map.spec.ts b/src/internal/__tests__/validate-map.spec.ts
new file mode 100644
index 00000000..8856b29c
--- /dev/null
+++ b/src/internal/__tests__/validate-map.spec.ts
@@ -0,0 +1,36 @@
+/**
+ * @file Unit Tests - validateMap
+ * @module mlly/internal/tests/unit/validateMap
+ */
+
+import { ErrorCode, type NodeError } from '@flex-development/errnode'
+import testSubject from '../validate-map'
+
+describe('unit:internal/validateMap', () => {
+  let name: string
+
+  beforeEach(() => {
+    name = 'options.extension_format_map'
+  })
+
+  it('should return true if value is an instance of Map', () => {
+    expect(testSubject(new Map(), name)).to.be.true
+  })
+
+  it('should throw if value is not an instance of Map', () => {
+    // Arrange
+    const code: ErrorCode = ErrorCode.ERR_INVALID_ARG_TYPE
+    let error: NodeError<TypeError>
+
+    // Act
+    try {
+      testSubject(new Set(), name)
+    } catch (e: unknown) {
+      error = e as typeof error
+    }
+
+    // Expect
+    expect(error!).to.be.instanceof(TypeError)
+    expect(error!).to.have.property('code').equal(code)
+  })
+})
diff --git a/src/internal/validate-map.ts b/src/internal/validate-map.ts
new file mode 100644
index 00000000..94fe854c
--- /dev/null
+++ b/src/internal/validate-map.ts
@@ -0,0 +1,33 @@
+/**
+ * @file Internal - validateMap
+ * @module mlly/internal/validateMap
+ */
+
+import { ERR_INVALID_ARG_TYPE, type NodeError } from '@flex-development/errnode'
+
+/**
+ * Checks if given `value` is a {@linkcode Map}.
+ *
+ * Throws [`ERR_INVALID_ARG_TYPE`][1] if the `value` is not a {@linkcode Map}.
+ *
+ * [1]: https://nodejs.org/api/errors.html#err_invalid_arg_value
+ *
+ * @see {@linkcode ERR_INVALID_ARG_TYPE}
+ *
+ * @template K - Map key type(s)
+ * @template V - Item type(s)
+ *
+ * @param {unknown} value - Value supplied by user
+ * @param {string} name - Name of invalid argument or property
+ * @return {value is Map<K, V>} `true` if `value` is a {@linkcode Map}
+ * @throws {NodeError<TypeError>} If `value` is not a {@linkcode Map}
+ */
+function validateMap<K extends string = string, V = unknown>(
+  value: unknown,
+  name: string
+): value is Map<K, V> {
+  if (value instanceof Map) return true
+  throw new ERR_INVALID_ARG_TYPE(name, ['Map'], value)
+}
+
+export default validateMap