Add min properties assertion

Author: Oleg

src/commonMain/kotlin/smirnov/oleg/json/schema/internal/SchemaLoader.kt

@@ -22,6 +22,7 @@ import smirnov.oleg.json.schema.internal.factories.number.MaximumAssertionFactor
 import smirnov.oleg.json.schema.internal.factories.number.MinimumAssertionFactory
 import smirnov.oleg.json.schema.internal.factories.number.MultipleOfAssertionFactory
 import smirnov.oleg.json.schema.internal.factories.`object`.MaxPropertiesAssertionFactory
+import smirnov.oleg.json.schema.internal.factories.`object`.MinPropertiesAssertionFactory
 import smirnov.oleg.json.schema.internal.factories.string.MaxLengthAssertionFactory
 import smirnov.oleg.json.schema.internal.factories.string.MinLengthAssertionFactory
 import smirnov.oleg.json.schema.internal.factories.string.PatternAssertionFactory
@@ -44,6 +45,7 @@ private val factories: List<AssertionFactory> = listOf(
   UniqueItemsAssertionFactory,
   ContainsAssertionFactory,
   MaxPropertiesAssertionFactory,
+  MinPropertiesAssertionFactory,
 )
 
 class SchemaLoader {

src/commonMain/kotlin/smirnov/oleg/json/schema/internal/factories/object/MinPropertiesAssertion.kt

@@ -0,0 +1,22 @@
+package smirnov.oleg.json.schema.internal.factories.`object`
+
+import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.intOrNull
+import smirnov.oleg.json.schema.internal.JsonSchemaAssertion
+import smirnov.oleg.json.schema.internal.LoadingContext
+import smirnov.oleg.json.schema.internal.factories.AbstractAssertionFactory
+
+@Suppress("unused")
+internal object MinPropertiesAssertionFactory : AbstractAssertionFactory("minProperties") {
+  override fun createFromProperty(element: JsonElement, context: LoadingContext): JsonSchemaAssertion {
+    require(element is JsonPrimitive && !element.isString) { "$property must be an integer" }
+    val minPropertiesValue = requireNotNull(element.intOrNull) { "$property must be a valid integer" }
+    require(minPropertiesValue >= 0) { "$property must be a non-negative integer" }
+    return PropertiesNumberAssertion(
+      context.schemaPath,
+      minPropertiesValue,
+      errorMessage = "must be greater or equal to",
+    ) { a, b -> a >= b }
+  }
+}

src/commonTest/kotlin/smirnov/oleg/json/schema/assertions/object/JsonSchemaMinPropertiesValidationTest.kt

@@ -0,0 +1,126 @@
+package smirnov.oleg.json.schema.assertions.`object`
+
+import io.kotest.assertions.asClue
+import io.kotest.assertions.throwables.shouldThrow
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.collections.shouldContainExactly
+import io.kotest.matchers.collections.shouldHaveSize
+import io.kotest.matchers.shouldBe
+import kotlinx.serialization.json.JsonNull
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.buildJsonArray
+import kotlinx.serialization.json.buildJsonObject
+import smirnov.oleg.json.pointer.JsonPointer
+import smirnov.oleg.json.schema.JsonSchema
+import smirnov.oleg.json.schema.KEY
+import smirnov.oleg.json.schema.ValidationError
+
+@Suppress("unused")
+class JsonSchemaMinPropertiesValidationTest : FunSpec() {
+  init {
+    val schema = JsonSchema.fromDescription(
+      """
+      {
+        "${KEY}schema": "http://json-schema.org/draft-07/schema#",
+        "minProperties": 2
+      }
+      """.trimIndent()
+    )
+
+    listOf(
+      buildJsonObject {
+        put("test1", JsonPrimitive("a"))
+        put("test2", JsonPrimitive("b"))
+      },
+      buildJsonObject {
+        put("test1", JsonPrimitive("a"))
+        put("test2", JsonPrimitive("b"))
+        put("test3", JsonPrimitive("c"))
+      },
+    ).forEach {
+      test("object with ${it.size} properties passes validation") {
+        val errors = mutableListOf<ValidationError>()
+        val valid = schema.validate(it, errors::add)
+        it.asClue {
+          valid shouldBe true
+          errors shouldHaveSize 0
+        }
+      }
+    }
+
+    listOf(
+      buildJsonObject { },
+      buildJsonObject {
+        put("test1", JsonPrimitive("a"))
+      },
+    ).forEach {
+      test("object with ${it.size} properties fails validation") {
+
+        val errors = mutableListOf<ValidationError>()
+        val valid = schema.validate(it, errors::add)
+        it.asClue {
+          valid shouldBe false
+          errors.shouldContainExactly(
+            ValidationError(
+              schemaPath = JsonPointer("/minProperties"),
+              objectPath = JsonPointer.ROOT,
+              message = "number of properties must be greater or equal to 2",
+            )
+          )
+        }
+      }
+    }
+
+    test("reports negative value") {
+      shouldThrow<IllegalArgumentException> {
+        JsonSchema.fromDescription(
+          """
+          {
+            "${KEY}schema": "http://json-schema.org/draft-07/schema#",
+            "minProperties": -1
+          }
+          """.trimIndent()
+        )
+      }.message shouldBe "minProperties must be a non-negative integer"
+    }
+
+    listOf(
+      JsonPrimitive(42.5),
+      JsonPrimitive(Int.MAX_VALUE.toLong() + 1),
+      JsonPrimitive(true),
+      JsonNull,
+    ).forEach {
+      test("reports not valid integer value $it") {
+        shouldThrow<IllegalArgumentException> {
+          JsonSchema.fromDescription(
+            """
+            {
+              "${KEY}schema": "http://json-schema.org/draft-07/schema#",
+              "minProperties": $it
+            }
+            """.trimIndent()
+          )
+        }.message shouldBe "minProperties must be a valid integer"
+      }
+    }
+
+    listOf(
+      JsonPrimitive("test"),
+      buildJsonObject { },
+      buildJsonArray { },
+    ).forEach {
+      test("reports not integer value $it") {
+        shouldThrow<IllegalArgumentException> {
+          JsonSchema.fromDescription(
+            """
+            {
+              "${KEY}schema": "http://json-schema.org/draft-07/schema#",
+              "minProperties": $it
+            }
+            """.trimIndent()
+          )
+        }.message shouldBe "minProperties must be an integer"
+      }
+    }
+  }
+}