Add unit tests

[hlibmurphy]

Added untreated unit tests.
Going to correct the code soon.

[Rommelua]

Java Cl checks failed. Before making a Pull Request (or a new commit to an already existing PR), you need to write the mvn clean package command in the terminal and make sure that all checks pass. After that, the mentor will be able to review the homework

[olekskov]

Build is still failing due some tests

[Rommelua]

Before you create PR with your homework, you need to go through the checklist under the task and correct all the points described there. The mentor will not check the work until the checklist points are corrected

[Rommelua]

add OK-test

[Rommelua]

Suggested change

	void fruitTransactionWithNegativeAmount_NotOk() {
	void of_NegativeAmount_NotOk() {

[olekskov]

Good job overall, approved

For future: files required for testing should be in resources folder of test package, not in project root folder