JavaExercism/exercises/nucleotide-count/src/test/java/NucleotideTest.java

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

import org.junit.Test;

public class NucleotideTest {
  @Test
  public void testEmptyDnaStringHasNoAdenosine() {
    DNA dna = new DNA("");
    assertThat(dna.count('A')).isEqualTo(0);
  }

  @Test
  public void testEmptyDnaStringHasNoNucleotides() {
    DNA dna = new DNA("");
    assertThat(dna.nucleotideCounts()).hasSize(4).contains(
        entry('A', 0),
        entry('C', 0),
        entry('G', 0),
        entry('T', 0)
    );
  }

  @Test
  public void testRepetitiveCytidineGetsCounted() {
    DNA dna = new DNA("CCCCC");
    assertThat(dna.count('C')).isEqualTo(5);
  }

  @Test
  public void testRepetitiveSequenceWithOnlyGuanosine() {
    DNA dna = new DNA("GGGGGGGG");
    assertThat(dna.nucleotideCounts()).hasSize(4).contains(
        entry('A', 0),
        entry('C', 0),
        entry('G', 8),
        entry('T', 0)
    );
  }

  @Test
  public void testCountsOnlyThymidine() {
    DNA dna = new DNA("GGGGGTAACCCGG");
    assertThat(dna.count('T')).isEqualTo(1);
  }

  @Test
  public void testCountsANucleotideOnlyOnce() {
    DNA dna = new DNA("CGATTGGG");
    dna.count('T');
    assertThat(dna.count('T')).isEqualTo(2);
  }

  @Test
  public void testDnaCountsDoNotChangeAfterCountingAdenosine() {
    DNA dna = new DNA("GATTACA");
    dna.count('A');
    assertThat(dna.nucleotideCounts()).hasSize(4).contains(
        entry('A', 3),
        entry('C', 1),
        entry('G', 1),
        entry('T', 2)
    );
  }

  @Test(expected = IllegalArgumentException.class)
  public void testValidatesNucleotides() {
    DNA dna = new DNA("GACT");
    dna.count('X');
  }

  @Test
  public void testCountsAllNucleotides() {
    String s = "AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC";
    DNA dna = new DNA(s);
    assertThat(dna.nucleotideCounts()).hasSize(4).contains(
        entry('A', 20),
        entry('C', 12),
        entry('G', 17),
        entry('T', 21)
    );
  }
}