Convert isLeapYear to instance method. Doing this so that we can have year be an instance variable. That way we can have access to it in the isDivisibleBy method. It will make it very easy to read. This also makes Year like a Wrapper class. I'd imagine that Year could hold other properties that makes a year a year.

AYearShould.java

package tech.pathtoprogramming.tdd;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.CsvSource;

import static org.assertj.core.api.Assertions.assertThat;

class AYearShould {

    @ParameterizedTest
    @CsvSource({
            "2001,false",
            "1996,true",
            "1992,true",
            "1900,false",
            "2000,true"
    })
    void determineWhetherAGivenYearIsALeapYearOrNot(int givenYear, boolean isExpectedLeapYear) {
        boolean isLeapYear = new Year().isLeapYear(givenYear);

        assertThat(isLeapYear).isEqualTo(isExpectedLeapYear);
    }
}

class Year {

    private static boolean isDivisibleBy(int year, int four) {
        return year % four == 0;
    }

    public boolean isLeapYear(int year) {
        if (isDivisibleBy(year, 4) && (year % 100 != 0 || isDivisibleBy(year, 400))) {
            return true;
        }
        return false;
    }
}