add support for maxProperties keyword

core/pom.xml

@@ -133,6 +133,7 @@
                     <include>**/tests/draft2020-12/maxItems.json</include>
                     <include>**/tests/draft2020-12/maxLength.json</include>
                     <include>**/tests/draft2020-12/maximum.json</include>
+                    <include>**/tests/draft2020-12/maxProperties.json</include>
                     <include>**/tests/draft2020-12/minItems.json</include>
                     <include>**/tests/draft2020-12/minLength.json</include>
                     <include>**/tests/draft2020-12/minimum.json</include>

core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/validation/MaxPropertiesKeyword.java

@@ -0,0 +1,74 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.vocab.validation;
+
+import io.github.sebastiantoepfer.ddd.common.Media;
+import io.github.sebastiantoepfer.jsonschema.InstanceType;
+import io.github.sebastiantoepfer.jsonschema.keyword.Assertion;
+import jakarta.json.JsonObject;
+import jakarta.json.JsonValue;
+import java.math.BigInteger;
+import java.util.Objects;
+
+/**
+ * /**
+ * <b>maxProperties</b> : <i>Integer</i>
+ * An object instance is valid if its number of properties is less than, or equal to, the value of this keyword.<br/>
+ * keyword.<br/>
+ * <br/>
+ * <ul>
+ * <li>assertion</li>
+ * </ul>
+ *
+ * source: https://www.learnjsonschema.com/2020-12/validation/maxproperties/
+ * spec: https://json-schema.org/draft/2020-12/json-schema-validation.html#section-6.5.1
+ */
+final class MaxPropertiesKeyword implements Assertion {
+
+    static final String NAME = "maxProperties";
+    private final BigInteger maxProperties;
+
+    public MaxPropertiesKeyword(final BigInteger maxProperties) {
+        this.maxProperties = maxProperties;
+    }
+
+    @Override
+    public boolean hasName(final String name) {
+        return Objects.equals(NAME, name);
+    }
+
+    @Override
+    public <T extends Media<T>> T printOn(final T media) {
+        return media.withValue(NAME, maxProperties);
+    }
+
+    @Override
+    public boolean isValidFor(final JsonValue instance) {
+        return !InstanceType.OBJECT.isInstance(instance) || hasMaxProperties(instance.asJsonObject());
+    }
+
+    private boolean hasMaxProperties(final JsonObject object) {
+        return object.keySet().size() <= maxProperties.intValue();
+    }
+}

core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/validation/ValidationVocabulary.java

@@ -49,6 +49,7 @@ public ValidationVocabulary(final JsonProvider jsonContext) {
             new AnyKeywordType(ConstKeyword.NAME, ConstKeyword::new),
             new ArrayKeywordType(EnumKeyword.NAME, EnumKeyword::new),
             new ObjectKeywordType(DependentRequiredKeyword.NAME, DependentRequiredKeyword::new),
+            new IntegerKeywordType(jsonContext, MaxPropertiesKeyword.NAME, MaxPropertiesKeyword::new),
             new StringKeywordType(jsonContext, PatternKeyword.NAME, PatternKeyword::new),
             new IntegerKeywordType(jsonContext, MinLengthKeyword.NAME, MinLengthKeyword::new),
             new IntegerKeywordType(jsonContext, MaxLengthKeyword.NAME, MaxLengthKeyword::new),

core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/validation/MaxPropertiesKeywordTest.java

@@ -0,0 +1,107 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.vocab.validation;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.hasEntry;
+import static org.hamcrest.Matchers.is;
+
+import io.github.sebastiantoepfer.ddd.media.core.HashMapMedia;
+import io.github.sebastiantoepfer.jsonschema.core.DefaultJsonSchemaFactory;
+import io.github.sebastiantoepfer.jsonschema.core.keyword.type.IntegerKeywordType;
+import io.github.sebastiantoepfer.jsonschema.keyword.Keyword;
+import jakarta.json.Json;
+import jakarta.json.JsonObject;
+import jakarta.json.JsonValue;
+import jakarta.json.spi.JsonProvider;
+import java.math.BigInteger;
+import org.hamcrest.Matcher;
+import org.junit.jupiter.api.Test;
+
+class MaxPropertiesKeywordTest {
+
+    @Test
+    void should_know_his_name() {
+        final Keyword enumKeyword = createKeywordFrom(Json.createObjectBuilder().add("maxProperties", 2).build());
+
+        assertThat(enumKeyword.hasName("maxProperties"), is(true));
+        assertThat(enumKeyword.hasName("test"), is(false));
+    }
+
+    @Test
+    void should_be_printable() {
+        assertThat(
+            createKeywordFrom(Json.createObjectBuilder().add("maxProperties", 2).build()).printOn(new HashMapMedia()),
+            (Matcher) hasEntry(is("maxProperties"), is(BigInteger.valueOf(2)))
+        );
+    }
+
+    @Test
+    void should_be_valid_for_non_objects() {
+        assertThat(
+            createKeywordFrom(Json.createObjectBuilder().add("maxProperties", 2).build())
+                .asAssertion()
+                .isValidFor(JsonValue.EMPTY_JSON_ARRAY),
+            is(true)
+        );
+    }
+
+    @Test
+    void should_be_valid_for_less_properties() {
+        assertThat(
+            createKeywordFrom(Json.createObjectBuilder().add("maxProperties", 2).build())
+                .asAssertion()
+                .isValidFor(Json.createObjectBuilder().add("foo", 3).build()),
+            is(true)
+        );
+    }
+
+    @Test
+    void should_be_valid_exact_properties_count() {
+        assertThat(
+            createKeywordFrom(Json.createObjectBuilder().add("maxProperties", 2).build())
+                .asAssertion()
+                .isValidFor(Json.createObjectBuilder().add("foo", 3).add("bar", "hi").build()),
+            is(true)
+        );
+    }
+
+    @Test
+    void should_be_invalid_for_more_properties() {
+        assertThat(
+            createKeywordFrom(Json.createObjectBuilder().add("maxProperties", 2).build())
+                .asAssertion()
+                .isValidFor(Json.createObjectBuilder().add("foo", 3).add("bar", "hi").add("baz", true).build()),
+            is(false)
+        );
+    }
+
+    private static Keyword createKeywordFrom(final JsonObject json) {
+        return new IntegerKeywordType(
+            JsonProvider.provider(),
+            "maxProperties",
+            MaxPropertiesKeyword::new
+        ).createKeyword(new DefaultJsonSchemaFactory().create(json));
+    }
+}