diff --git a/.gitignore b/.gitignore
index c94ba35..7c4b882 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,5 @@ node_modules
 package-lock.json
 build
 .idea
-coverage
\ No newline at end of file
+coverage
+.env
\ No newline at end of file
diff --git a/README.md b/README.md
index 38edf88..d905678 100644
--- a/README.md
+++ b/README.md
@@ -160,6 +160,12 @@ npm install
 npm run build
 ```
 
+### Run tests
+
+```shell
+npm run test
+```
+
 Compiled JavaScript will be placed in `/build` folder.
 
 _Made by Michał Szajner_
\ No newline at end of file
diff --git a/jest.config.js b/jest.config.js
index b413e10..3f0dfa1 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -2,4 +2,7 @@
 module.exports = {
   preset: 'ts-jest',
   testEnvironment: 'node',
+  "testPathIgnorePatterns" : [
+    "./build",
+  ]
 };
\ No newline at end of file
diff --git a/package.json b/package.json
index 0b2d3cd..79c3d58 100644
--- a/package.json
+++ b/package.json
@@ -18,6 +18,7 @@
     "googleapis": "^120.0.0"
   },
   "devDependencies": {
+    "dotenv": "^16.3.1",
     "del-cli": "^5.0.0",
     "ts-jest": "^29.1.1",
     "typescript": "^5.1.6"
diff --git a/src/config/configurations.ts b/src/config/configurations.ts
index bf67b67..45001c5 100644
--- a/src/config/configurations.ts
+++ b/src/config/configurations.ts
@@ -1,5 +1,4 @@
 import {DateTimeRenderOption, Dimension, InsertDataOption, ValueInputOption, ValueRenderOption} from "../types/types";
-import {GoogleSheetsAuth} from "../auth/google-sheets-auth";
 
 export interface GetRequestConfiguration {
     range?: string;
@@ -34,7 +33,7 @@ export interface ClearRequestConfiguration {
 }
 
 export interface Configuration {
-    auth: GoogleSheetsAuth;
+    auth: any;
     spreadsheetId: string;
     sheet?: string;
     range?: string;
diff --git a/src/sheets/__tests__/sheets-connection.test.ts b/src/sheets/__tests__/sheets-connection.test.ts
index 0999de4..3d83826 100644
--- a/src/sheets/__tests__/sheets-connection.test.ts
+++ b/src/sheets/__tests__/sheets-connection.test.ts
@@ -1,5 +1,225 @@
-import { test, expect } from '@jest/globals';
+import {describe, expect, test} from '@jest/globals';
+import {GoogleSheetsAuth} from "../../auth/google-sheets-auth";
+import {SheetsConnection} from "../sheets-connection";
+import dotenv from 'dotenv';
+
+dotenv.config();
+
+// Auth setup
+const key = process.env.GOOGLE_KEY!.toString().split('\\n').map(i => i + "\n").join("");
+
+const googleAuthWrapper = new GoogleSheetsAuth({
+    email: process.env.GOOGLE_EMAIL!,
+    key: key
+}).login();
+
+describe('SheetsConnection main methods', () => {
+
+    const sheetsConnection = new SheetsConnection({
+        spreadsheetId: process.env.SHEET_ID!,
+        auth: googleAuthWrapper,
+        sheet: "Sheet1",
+        range: "A1:B"
+    });
+
+    test('Expect get method to work', async () => {
+        expect(await sheetsConnection.get()).toBeTruthy();
+    });
+
+    test('Expect append method to work', async () => {
+        expect(await sheetsConnection.append([[
+            "test1",
+            "test2"
+        ]])).toBeTruthy();
+    });
+
+    test('Expect update method to work', async () => {
+        expect(await sheetsConnection.update([[
+            "test3",
+            "test4"
+        ]])).toBeTruthy();
+    });
+
+    test('Expect clear method to work', async () => {
+        expect(await sheetsConnection.clear()).toBeTruthy();
+    });
+
+});
+
+describe('Range logic checks', () => {
+
+    test('Expect range to be this.sheetRange when sheet and range in constructor', async () => {
+        const range = "A1:B2";
+        const sheet = "Sheet1";
+
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            sheet,
+            range
+        });
+
+        const response = await sheetsConnection.get();
+
+        expect(response.data.range).toBe(sheet + "!" + range);
+    });
+
+    test('Expect range to be `${cfg.sheet}!${cfg.range}` when sheet and range in method', async () => {
+        const range = "A1:B2";
+        const sheet = "Sheet1";
+
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+        });
+
+        const response = await sheetsConnection.get({
+            sheet,
+            range
+        });
+
+        expect(response.data.range).toBe(sheet + "!" + range);
+    });
+
+    test('Expect range to be `${cfg.sheet}!${cfg.range}` when sheet and range in method and constructor', async () => {
+        const range = "A1:B2";
+        const sheet = "Sheet1";
+
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            sheet: "Sheet2",
+            range: "C1:D2"
+        });
+
+        const response = await sheetsConnection.get({
+            sheet,
+            range
+        });
+
+        expect(response.data.range).toBe(sheet + "!" + range);
+    });
+
+    test('Expect range to be `${this.sheet}!${cfg.range}` when sheet and range in constructor and range in method', async () => {
+        const range = "A1:B2";
+        const sheet = "Sheet1";
+
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            sheet,
+            range: "C1:D2"
+        });
+
+        const response = await sheetsConnection.get({
+            range
+        });
+
+        expect(response.data.range).toBe(sheet + "!" + range);
+    });
+
+    test('Expect range to be `${this.sheet}!${cfg.range}` when sheet in constructor and range in method', async () => {
+        const range = "A1:B2";
+        const sheet = "Sheet1";
+
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            sheet,
+        });
+
+        const response = await sheetsConnection.get({
+            range
+        });
+
+        expect(response.data.range).toBe(sheet + "!" + range);
+    });
+
+    test('Expect error when sheet only in constructor', async () => {
+        const sheet = "Sheet1";
+
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            sheet,
+        });
+
+        await expect(sheetsConnection.get()).rejects.toThrowError("Specify range or sheet in method or in constructor");
+    });
+
+    test('Expect error when range only in constructor', async () => {
+        const range = "A1:B2";
+
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            range,
+        });
+
+        await expect(sheetsConnection.get()).rejects.toThrowError("Specify range or sheet in method or in constructor");
+    });
+
+    test('Expect error when sheet only in method', async () => {
+        const sheet = "Sheet1";
+
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+        });
+
+        await expect(sheetsConnection.get({sheet})).rejects.toThrowError("Specify range or sheet in method or in constructor");
+    });
+
+    test('Expect error when range only in method', async () => {
+        const range = "A1:B2";
+
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+        });
+
+        await expect(sheetsConnection.get({range})).rejects.toThrowError("Specify range or sheet in method or in constructor");
+    });
+
+    test('Expect error when sheet and range in constructor and sheet in method', async () => {
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            sheet: "Sheet1",
+            range: "A1:B2"
+        });
+
+        await expect(sheetsConnection.get({sheet: "Sheet2"})).rejects.toThrowError("Specify range or sheet in method or in constructor");
+    });
+
+    test('Expect error when range in constructor and sheet in method', async () => {
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            range: "A1:B2"
+        });
+
+        await expect(sheetsConnection.get({sheet: "Sheet2"})).rejects.toThrowError("Specify range or sheet in method or in constructor");
+    });
+
+    test('Expect error when range in constructor and range in method', async () => {
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            range: "A1:B2"
+        });
+
+        await expect(sheetsConnection.get({range: "C1:D2"})).rejects.toThrowError("Specify range or sheet in method or in constructor");
+    });
+
+    test('Expect error when sheet in constructor and sheet in method', async () => {
+        const sheetsConnection = new SheetsConnection({
+            spreadsheetId: process.env.SHEET_ID!,
+            auth: googleAuthWrapper,
+            sheet: "Sheet1"
+        });
+
+        await expect(sheetsConnection.get({sheet: "Sheet2"})).rejects.toThrowError("Specify range or sheet in method or in constructor");
+    });
 
-test('adds 1 + 2 to equal 3', () => {
-    expect(1+2).toBe(3);
 });
\ No newline at end of file
diff --git a/src/sheets/sheets-connection.ts b/src/sheets/sheets-connection.ts
index c9cce41..e0ce156 100644
--- a/src/sheets/sheets-connection.ts
+++ b/src/sheets/sheets-connection.ts
@@ -13,7 +13,7 @@ export class SheetsConnection {
     private sheets: sheets_v4.Sheets = google.sheets("v4");
     public readonly sheetRange?: string;
     public readonly startingSheetIndex?: number;
-    private readonly authWrapper: GoogleSheetsAuth;
+    private readonly authWrapper: any;
     private readonly spreadsheetId: string;
     private readonly sheet?: string;
     private readonly range?: string;
@@ -57,11 +57,11 @@ export class SheetsConnection {
         return await this.sheets.spreadsheets.values.append(this.appendRequestPayload(data, {...cfg}));
     };
 
-    public update = async (data: any[], cfg: UpdateRequestConfiguration) => {
+    public update = async (data: any[], cfg?: UpdateRequestConfiguration) => {
         return await this.sheets.spreadsheets.values.update(this.updateRequestPayload(data, cfg));
     };
 
-    public clear = async (cfg: ClearRequestConfiguration) => {
+    public clear = async (cfg?: ClearRequestConfiguration) => {
         return await this.sheets.spreadsheets.values.clear(this.clearRequestPayload(cfg));
     };
 
@@ -128,7 +128,9 @@ export class SheetsConnection {
             (!this.sheetRange && cfg?.sheet && !cfg?.range) ||
             (this.sheet && !this.range && !cfg?.sheet && !cfg?.range) ||
             (this.sheet && !this.range && cfg?.sheet && !cfg?.range) ||
-            (this.sheetRange && cfg?.sheet && !cfg?.range)
+            (this.sheetRange && cfg?.sheet && !cfg?.range) ||
+            (!this.sheet && !this.range && !cfg?.sheet && cfg?.range) ||
+            (!this.sheet && this.range && !cfg?.sheet && cfg?.range)
         ) {
             throw new Error("Specify range or sheet in method or in constructor");
         }