From 1756bae4bced1e7dd22b9ac5b1a3ff7a4494be7d Mon Sep 17 00:00:00 2001
From: Anna Nikiforova <annanicky90@gmail.com>
Date: Tue, 30 Dec 2025 23:13:40 +0400
Subject: [PATCH 1/3] qa array reduce method solution

---
 src/reduce.test.js | 66 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 2 deletions(-)

diff --git a/src/reduce.test.js b/src/reduce.test.js
index 47a892f..3411ce1 100644
--- a/src/reduce.test.js
+++ b/src/reduce.test.js
@@ -11,9 +11,71 @@ describe('reduce', () => {
     delete Array.prototype.reduce2;
   });
 
-  it('should ', () => {
+  let callback;
 
+  beforeEach(() => {
+    callback = jest.fn().mockImplementation((a, b) => a + b);
   });
 
-  // Add tests here
+  it('should be declared', () => {
+    expect(reduce).toBeInstanceOf(Function);
+  });
+
+  it('should not mutate array', () => {
+    const array = [1, 2, 3, 4];
+
+    array.reduce2(callback, 0);
+
+    expect(array).toEqual(array);
+  });
+
+  it('should run callback array`s length times if initialValue is', () => {
+    const array = [1, 2, 3, 4];
+
+    array.reduce2(callback, 0);
+
+    expect(callback).toHaveBeenCalledTimes(array.length); ;
+  });
+
+  it('should run callback array`s length - 1 times if no initialValue', () => {
+    const array = [1, 2, 3, 4];
+
+    array.reduce2(callback);
+
+    expect(callback).toHaveBeenCalledTimes(array.length - 1); ;
+  });
+
+  it('should not run callback if array is empty', () => {
+    const array = [];
+
+    array.reduce2(callback);
+
+    expect(callback).toHaveBeenCalledTimes(0); ;
+  });
+
+  it('should run callback with correct arguments', () => {
+    const array = [1, 2, 3, 4];
+
+    array.reduce2(callback, 0);
+
+    expect(callback).toHaveBeenNthCalledWith(1, 0, 1, 0, array);
+    expect(callback).toHaveBeenNthCalledWith(2, 1, 2, 1, array);
+    expect(callback).toHaveBeenNthCalledWith(3, 3, 3, 2, array);
+    expect(callback).toHaveBeenNthCalledWith(4, 6, 4, 3, array);
+  });
+
+  it('should return initial value if array is empty', () => {
+    const array = [];
+    const initialValue = 0;
+    const result = array.reduce2(callback, initialValue);
+
+    expect(result).toBe(initialValue); ;
+  });
+
+  it('should return undefined if array is empty and no initial value', () => {
+    const array = [];
+    const result = array.reduce2(callback);
+
+    expect(result).toBe(undefined); ;
+  });
 });

From 9556f8df7c4e5a254006740f1fdf81465ed09c6d Mon Sep 17 00:00:00 2001
From: Anna Nikiforova <annanicky90@gmail.com>
Date: Tue, 30 Dec 2025 23:37:57 +0400
Subject: [PATCH 2/3] fix the issues

---
 src/reduce.test.js | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/src/reduce.test.js b/src/reduce.test.js
index 3411ce1..5a0edc5 100644
--- a/src/reduce.test.js
+++ b/src/reduce.test.js
@@ -24,9 +24,11 @@ describe('reduce', () => {
   it('should not mutate array', () => {
     const array = [1, 2, 3, 4];
 
+    const copy = [...array];
+
     array.reduce2(callback, 0);
 
-    expect(array).toEqual(array);
+    expect(array).toEqual(copy);
   });
 
   it('should run callback array`s length times if initialValue is', () => {
@@ -56,12 +58,14 @@ describe('reduce', () => {
   it('should run callback with correct arguments', () => {
     const array = [1, 2, 3, 4];
 
-    array.reduce2(callback, 0);
+    const result = array.reduce2(callback, 0);
 
     expect(callback).toHaveBeenNthCalledWith(1, 0, 1, 0, array);
     expect(callback).toHaveBeenNthCalledWith(2, 1, 2, 1, array);
     expect(callback).toHaveBeenNthCalledWith(3, 3, 3, 2, array);
     expect(callback).toHaveBeenNthCalledWith(4, 6, 4, 3, array);
+
+    expect(result).toBe(10);
   });
 
   it('should return initial value if array is empty', () => {
@@ -71,11 +75,4 @@ describe('reduce', () => {
 
     expect(result).toBe(initialValue); ;
   });
-
-  it('should return undefined if array is empty and no initial value', () => {
-    const array = [];
-    const result = array.reduce2(callback);
-
-    expect(result).toBe(undefined); ;
-  });
 });

From 4dec39b8f1bb052d56e40bf9945a446a872222c6 Mon Sep 17 00:00:00 2001
From: Anna Nikiforova <annanicky90@gmail.com>
Date: Wed, 31 Dec 2025 00:11:32 +0400
Subject: [PATCH 3/3] fix the issues 2

---
 src/reduce.test.js | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/src/reduce.test.js b/src/reduce.test.js
index 5a0edc5..c74f018 100644
--- a/src/reduce.test.js
+++ b/src/reduce.test.js
@@ -34,25 +34,19 @@ describe('reduce', () => {
   it('should run callback array`s length times if initialValue is', () => {
     const array = [1, 2, 3, 4];
 
-    array.reduce2(callback, 0);
+    const result = array.reduce2(callback, 0);
 
     expect(callback).toHaveBeenCalledTimes(array.length); ;
+    expect(result).toBe(10);
   });
 
   it('should run callback array`s length - 1 times if no initialValue', () => {
     const array = [1, 2, 3, 4];
 
-    array.reduce2(callback);
+    const result = array.reduce2(callback);
 
     expect(callback).toHaveBeenCalledTimes(array.length - 1); ;
-  });
-
-  it('should not run callback if array is empty', () => {
-    const array = [];
-
-    array.reduce2(callback);
-
-    expect(callback).toHaveBeenCalledTimes(0); ;
+    expect(result).toBe(10);
   });
 
   it('should run callback with correct arguments', () => {