add tests for default method implementations

lib/src/test/java/com/auth0/jwt/interfaces/ClaimTest.java

@@ -0,0 +1,93 @@
+package com.auth0.jwt.interfaces;
+
+import com.auth0.jwt.exceptions.JWTDecodeException;
+import org.junit.Test;
+
+import java.util.Date;
+import java.util.List;
+import java.util.Map;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+
+public class ClaimTest {
+
+    @Test
+    public void shouldGetInstantUsingDefault() {
+        Date date = new Date(1646667492000L);
+        Claim claim = new ClaimImplForTest(date);
+        assertThat(claim.asInstant(), is(date.toInstant()));
+    }
+
+    @Test
+    public void shouldGetNullInstantUsingDefault() {
+        Claim claim = new ClaimImplForTest(null);
+        assertThat(claim.asInstant(), is(nullValue()));
+    }
+
+    /**
+     * Implementation that does not override {@code asInstant()}
+     */
+    static class ClaimImplForTest implements Claim {
+        private final Date date;
+
+        ClaimImplForTest(Date date) {
+            this.date = date;
+        }
+
+        @Override
+        public boolean isNull() {
+            return false;
+        }
+
+        @Override
+        public Boolean asBoolean() {
+            return null;
+        }
+
+        @Override
+        public Integer asInt() {
+            return null;
+        }
+
+        @Override
+        public Long asLong() {
+            return null;
+        }
+
+        @Override
+        public Double asDouble() {
+            return null;
+        }
+
+        @Override
+        public String asString() {
+            return null;
+        }
+
+        @Override
+        public Date asDate() {
+            return date;
+        }
+
+        @Override
+        public <T> T[] asArray(Class<T> tClazz) throws JWTDecodeException {
+            return null;
+        }
+
+        @Override
+        public <T> List<T> asList(Class<T> tClazz) throws JWTDecodeException {
+            return null;
+        }
+
+        @Override
+        public Map<String, Object> asMap() throws JWTDecodeException {
+            return null;
+        }
+
+        @Override
+        public <T> T as(Class<T> tClazz) throws JWTDecodeException {
+            return null;
+        }
+    }
+}

lib/src/test/java/com/auth0/jwt/interfaces/PayloadTest.java

@@ -0,0 +1,83 @@
+package com.auth0.jwt.interfaces;
+
+import org.junit.Test;
+
+import java.util.Date;
+import java.util.List;
+import java.util.Map;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+
+public class PayloadTest {
+
+    @Test
+    public void shouldGetInstantFromDefault() {
+        Date date = new Date(1646667492000L);
+        Payload payload = new PayloadImplForTest(date);
+        assertThat(payload.getExpiresAtAsInstant(), is(date.toInstant()));
+        assertThat(payload.getIssuedAtAsInstant(), is(date.toInstant()));
+        assertThat(payload.getNotBeforeAsInstant(), is(date.toInstant()));
+    }
+
+    @Test
+    public void shouldGetInstantFromDefaultAsNu() {
+        Payload payload = new PayloadImplForTest(null);
+        assertThat(payload.getExpiresAtAsInstant(), is(nullValue()));
+        assertThat(payload.getIssuedAtAsInstant(), is(nullValue()));
+        assertThat(payload.getNotBeforeAsInstant(), is(nullValue()));
+    }
+
+    static class PayloadImplForTest implements Payload {
+        private final Date date;
+
+        PayloadImplForTest(Date date) {
+            this.date = date;
+        }
+
+        @Override
+        public String getIssuer() {
+            return null;
+        }
+
+        @Override
+        public String getSubject() {
+            return null;
+        }
+
+        @Override
+        public List<String> getAudience() {
+            return null;
+        }
+
+        @Override
+        public Date getExpiresAt() {
+            return date;
+        }
+
+        @Override
+        public Date getNotBefore() {
+            return date;
+        }
+
+        @Override
+        public Date getIssuedAt() {
+            return date;
+        }
+
+        @Override
+        public String getId() {
+            return null;
+        }
+
+        @Override
+        public Claim getClaim(String name) {
+            return null;
+        }
+
+        @Override
+        public Map<String, Claim> getClaims() {
+            return null;
+        }
+    }
+}