Common Mistakes Beginners Make Learning Software Testing

Recommended learning order for testers

1. SDLC, STLC, testing types and levels
2. Test design techniques: boundary, equivalence,
   decision tables, state transitions
3. Writing test cases and bug reports
4. Agile basics and a tracker such as Jira
5. SQL for data validation
6. API testing with Postman
7. One programming language (Java or Python)
8. UI automation (Selenium or Playwright)
9. Git and CI basics

Automation comes AFTER you can design good tests.

Requirement: Free shipping if order >= Rs 500
             OR customer is a premium member.

| Rule | Order >= 500 | Premium | Free shipping? |
|------|--------------|---------|----------------|
| 1    | Yes          | Yes     | Yes            |
| 2    | Yes          | No      | Yes            |
| 3    | No           | Yes     | Yes            |
| 4    | No           | No      | No             |

Each rule becomes at least one test case.
Also test the boundary: Rs 499, Rs 500, Rs 501.

Login - beyond the happy path

TC01  Valid email + valid password            -> dashboard
TC02  Valid email + wrong password            -> error, stay on page
TC03  Unregistered email                      -> generic error message
TC04  Blank email and password                -> field validation
TC05  Email with spaces before/after          -> trimmed or rejected clearly
TC06  Email with plus sign (a+b@mail.com)     -> accepted if valid
TC07  5 wrong attempts                        -> account lock or captcha
TC08  Password field                          -> characters masked
TC09  Back button after logout                -> no access to dashboard
TC10  Very long input (500+ chars)            -> handled gracefully

Title: Login fails for valid emails containing '+'
Environment: QA build 2.3.1, Chrome (latest), Windows 11
Severity: Medium   Priority: High

Steps:
1. Register with test+qa1@example.test
2. Log out
3. Log in with the same email and correct password

Expected: User reaches the dashboard
Actual: 'Invalid email format' error shown

Evidence: screenshot, network response (400)
Note: Same password works for emails without '+'

import java.time.Duration;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;

public class LoginWaitTest {
    // BAD: Thread.sleep(5000); - slow and still unreliable

    // GOOD: wait only until the element is actually ready
    static WebElement waitForClickable(WebDriver driver, By locator) {
        WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));
        return wait.until(ExpectedConditions.elementToBeClickable(locator));
    }

    // Prefer stable locators: By.id("login") or a data-testid attribute,
    // not long XPaths such as /html/body/div[3]/div/form/button[2]
    static final By LOGIN_BUTTON = By.cssSelector("[data-testid='login-button']");
}

# pip install pytest-playwright && playwright install
from playwright.sync_api import Page, expect

def test_wrong_password_shows_error(page: Page):
    page.goto("https://example.test/login")
    page.get_by_label("Email").fill("user@example.test")
    page.get_by_label("Password").fill("wrong-password")
    page.get_by_role("button", name="Log in").click()
    # expect() retries until the condition is met or times out - no sleep needed
    expect(page.get_by_text("Incorrect email or password")).to_be_visible()

Test case self-review

[ ] Each case linked to a requirement
[ ] Positive, negative and boundary cases included
[ ] Clear preconditions and test data
[ ] Steps simple enough for anyone to follow
[ ] One expected result per case
[ ] No duplicate cases
[ ] High-risk features covered first

Bug report self-review

[ ] Title states what fails and when
[ ] Environment and build listed
[ ] Numbered steps with exact data
[ ] Expected vs actual clearly stated
[ ] Evidence attached (screenshot, video, logs)
[ ] Severity reflects impact; priority reflects urgency
[ ] Checked it is not a duplicate

Automation self-review

[ ] No hard-coded sleeps
[ ] Stable locators (IDs, roles, test attributes)
[ ] Each test independent and repeatable
[ ] Test data created and cleaned up by the test
[ ] Clear assertion messages
[ ] Runs reliably 5 times in a row
[ ] Runs in CI, not only on my laptop