curry 함수 구현

src/curry.js

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+export default function curry(fn) {
+  return function curried(...args) {
+    if (args.length >= fn.length) {
+      return fn(...args);
+    } else {
+      return function recursion(...newArgs) {
+        return curried(...args, ...newArgs);
+      };
+    }
+  };
+}

src/test/curry.test.js

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+import curry from "../curry";
+
+describe("curry 테스트", () => {
+  const sum = (a, b, c) => a + b + c;
+  const join = (a, b, c) => `${a}_${b}_${c}`;
+
+  test("모든 인자를 한 번에 넘겨 호출 했을 때", () => {
+    const curriedSum = curry(sum);
+    const curriedJoin = curry(join);
+
+    expect(curriedSum(1, 2, 3)).toBe(6);
+    expect(curriedJoin(1, 2, 3)).toBe("1_2_3");
+  });
+
+  test("인자를 하나씩 전달했을 때", () => {
+    const curriedSum = curry(sum);
+    const curriedJoin = curry(join);
+
+    expect(curriedSum(1)(2)(3)).toBe(6);
+    expect(curriedJoin(1)(2)(3)).toBe("1_2_3");
+  });
+
+  test("여러 그룹으로 인자를 나누어 호출했을 때", () => {
+    const curriedSum = curry(sum);
+    const curriedJoin = curry(join);
+
+    expect(curriedSum(1, 2)(3)).toBe(6);
+    expect(curriedSum(1)(2, 3)).toBe(6);
+    expect(curriedJoin(1, 2)(3)).toBe("1_2_3");
+    expect(curriedJoin(1)(2, 3)).toBe("1_2_3");
+  });
+
+  test("인자가 추가적으로 있을 때", () => {
+    const curriedSum = curry(sum);
+
+    expect(curriedSum(1, 2, 3, 4)).toBe(6);
+  });
+});