assertj-json/src/test/java/com/devsoap/json/FieldTraversalAssertionTest.java

package com.devsoap.json;

import org.junit.jupiter.api.Test;

import static com.devsoap.json.JsonAssert.assertThat;

public class FieldTraversalAssertionTest {

    private static final String JSON = """
    {
      "level": 0,
      "root": {
        "level": 1,
        "child": {
          "level": 2,
           "child": {
              "level": 3,
              "last": 42
            }
        }
      }
    }
    """;

    @Test
    public void root() {
        assertThat(JSON).field("level").isEqualTo(0);
        assertThat(JSON).field("root").isNotNull();
    }

    @Test
    public void fieldTraversal() {
        assertThat(JSON)
                .field("root")
                .field("child")
                .field("level")
                .isEqualTo(2);
    }

    @Test
    public void pathTraversal() {
        assertThat(JSON)
                .path("root", "child", "level")
                .isEqualTo(2);
    }

    @Test
    public void firstFieldMatching() {
        assertThat(JSON)
                .firstField("child")
                .field("level")
                .isEqualTo(2);

        assertThat(JSON)
                .firstField("last")
                .isEqualTo(42);
    }

    @Test
    public void lastFieldMatching() {
        assertThat(JSON)
                .lastField("child")
                .field("level")
                .isEqualTo(3);

        assertThat(JSON)
                .lastField("level")
                .isEqualTo(3);
    }

    @Test
    public void nthFieldMatching() {
        assertThat(JSON)
                .nthField("child", 1)
                .field("level")
                .isEqualTo(3);

        for (var level=0; level<=3; level++) {
            assertThat(JSON)
                    .nthField("level", level)
                    .isEqualTo(level);
        }
    }

}