Implement a class `LoginForm` that simulates a login form commonly found on web pages. The `LoginForm` must include the following public methods (assume valid non-null strings are passed in for all parameters):

- `LoginForm(String expectedUsername, String expectedPassword)`: Constructor that takes in the expected username and password.
- `void input(String text)`: Takes the text as input for username if username doesn't already have a value; takes the text as input for password if username does have a value but password doesn't; ignores the text if both username and password already have a value.
- `void click(String button)`: If button is "Submit", submits the form; if button is "Reset", resets the form (the values for username and password); does nothing if button equals any other value.
- `boolean isLoggedIn()`: Returns true if the user is logged in; false otherwise.

Once a user has been successfully logged in by supplying a username and password that match the expected values and clicking submit, the `isLoggedIn` method returns true, and further input has no effect. If a user submits a wrong username and password combination, the form is reset.

Example:
```java
LoginForm login = new LoginForm("admin", "admin123");
login.input("test");
login.input("test123");
login.click("Submit");
login.isLoggedIn(); // returns false
login.input("admin");
login.input("admin123");
login.click("Reset");
login.isLoggedIn(); // returns false
login.click("Submit");
login.isLoggedIn(); // returns false
login.input("admin");
login.input("admin123");
login.input("test");
login.input("test123");
login.click("Submit");
login.isLoggedIn(); // returns true
login.input("test");
login.input("test123");
login.click("Submit");
login.isLoggedIn(); // returns true
```

**Problem 4: LoginFormTest**

Provide a JUnit test class `LoginFormTest` with five public test methods. Each method must test the described feature with at least one `assertEquals` method call:

- `void testCorrectUsernameIncorrectPassword()`: Tests that a correct username and an incorrect password do not allow the user to log in.
- `void testIncorrectUsernameCorrectPassword()`: Tests that an incorrect username and a correct password do not allow the user to log in.
- `void testCorrectCredentialsFirstTry()`: Tests that providing the correct username and password on the first try allows the user to log in.
- `void testIncorrectFirstCorrectSecond()`: Tests that the following steps allow the user to log in:
1. Provide incorrect credentials,
2. Submit,
3. Provide correct credentials,
4. Submit.
- `void testCorrectFirstIncorrectSecond()`: Tests that the user stays logged in after correct credentials are submitted, even if incorrect credentials are then submitted:
1. Provide correct credentials,
2. Submit,
3. Provide incorrect credentials,
4. Submit.