test: add tests for third parameter

Signed-off-by: Athan <[email protected]>

Author: kgryte

lib/node_modules/@stdlib/assert/is-almost-equal/docs/types/test.ts

@@ -28,6 +28,18 @@ import isAlmostEqual = require( './index' );
 	isAlmostEqual( 'beep', 'boop', 2 ); // $ExpectType boolean
 }
 
+// The compiler throws an error if the function is provided a third argument which is not a number...
+{
+	isAlmostEqual( 3.14, 3.14, '1' ); // $ExpectError
+	isAlmostEqual( 3.14, 3.14, true ); // $ExpectError
+	isAlmostEqual( 3.14, 3.14, false ); // $ExpectError
+	isAlmostEqual( 3.14, 3.14, null ); // $ExpectError
+	isAlmostEqual( 3.14, 3.14, undefined ); // $ExpectError
+	isAlmostEqual( 3.14, 3.14, [] ); // $ExpectError
+	isAlmostEqual( 3.14, 3.14, {} ); // $ExpectError
+	isAlmostEqual( 3.14, 3.14, ( x: number ): number => x ); // $ExpectError
+}
+
 // The compiler throws an error if the function is provided an unsupported number of arguments...
 {
 	isAlmostEqual(); // $ExpectError