1 files changed, 70 insertions, 0 deletions
diff --git a/tests/js/utils.mjs b/tests/js/utils.mjs
index 5a1507c..004af95 100644
--- a/tests/js/utils.mjs
+++ b/tests/js/utils.mjs
@@ -9,6 +9,7 @@ import {
 	getIn,
 	first,
 	promisify,
+	partial,
 } from "../../src/utils.mjs";
 
 const test_eq = t => {
@@ -275,6 +276,74 @@ const test_promisify = t => {
 	});
 };
 
+const test_partial = t => {
+	t.start("partial()");
+
+	t.test("empty values", () => {
+		const adder = (a, b, c) => a + b + c;
+
+		const adder1 = partial(adder);
+		assert.equal(adder1(1, 2, 3), 6);
+
+		const adder2 = partial(adder, 4, 5, 6);
+		assert.equal(adder2(), 15);
+
+		const noargs = () => "static";
+		assert.equal(partial(noargs)(), noargs());
+	});
+
+	t.test("too few arguments", () => {
+		const threeArgs = (a, b, c) => {
+			assert.notEqual(c, undefined);
+			return a + b + c
+		};
+
+		const add1 = partial(threeArgs, 1);
+		assert.throws(
+			() => add1(2),
+			assert.AssertionError,
+		);
+
+		const add1And2 = partial(threeArgs, 1, 2);
+		assert.throws(
+			() => add1And2(),
+			assert.AssertionError,
+		);
+
+		const addNothing = partial(threeArgs);
+		assert.throws(
+			() => addNothing(),
+			assert.AssertionError,
+		);
+	});
+
+	t.test("too many arguments", () => {
+		const twoArgs = (a, b) => a + b;
+
+		assert.equal(partial(twoArgs, 1)(2, 3), 3);
+		assert.equal(partial(twoArgs, 1, 2)(3), 3);
+	});
+
+	t.test("daily usage", () => {
+		const twoArg = (a, b) => a + b;
+
+		const numbers = [ 1, 2, 3, 4, 5 ];
+		assert.deepEqual(
+			numbers.map(partial(twoArg, 2)),
+			[ 3, 4, 5, 6, 7 ],
+		);
+	});
+
+	t.test("nested partials", () => {
+		const threeArgs = (a, b, c) => a + b + c;
+
+		const add1     = partial(threeArgs, 1);
+		const add1And2 = partial(add1,      2);
+
+		assert.equal(add1And2(3), 6);
+	});
+};
+
 
 await runner.runTests([
 	test_eq,
@@ -284,4 +353,5 @@ await runner.runTests([
 	test_getIn,
 	test_first,
 	test_promisify,
+	test_partial,
 ]);