Add a test to reproduce the issue

Author: OptimumCode

json-schema-validator/src/commonTest/kotlin/io/github/optimumcode/json/schema/cuncurrency/ConcurrentExecutionTest.kt

@@ -0,0 +1,65 @@
+package io.github.optimumcode.json.schema.cuncurrency
+
+import io.github.optimumcode.json.schema.JsonSchema
+import io.github.optimumcode.json.schema.OutputCollector
+import io.github.optimumcode.json.schema.SchemaType
+import io.kotest.assertions.throwables.shouldNotThrowAny
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.booleans.shouldBeTrue
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.buildJsonObject
+import kotlin.time.Duration.Companion.milliseconds
+
+class ConcurrentExecutionTest : FunSpec() {
+  init {
+    val schema =
+      JsonSchema.Companion.fromDefinition(
+        """
+        {
+          "properties": {
+            "inner": {
+              "type": "object",
+              "properties": {
+                "value": {
+                  "type": "string"
+                }
+              }
+            }
+          }
+        }
+        """.trimIndent(),
+        defaultType = SchemaType.DRAFT_2020_12,
+      )
+
+    test("BUG #224: JsonSchema can be used concurrently").config(coroutineTestScope = false) {
+      val target =
+        buildJsonObject {
+          put(
+            "inner",
+            buildJsonObject {
+              put("value", JsonPrimitive("test"))
+            },
+          )
+        }
+      shouldNotThrowAny {
+        coroutineScope {
+          withContext(Dispatchers.Default) {
+            repeat(1000) {
+              launch {
+                // delay is added to force suspension and increase changes of catching a concurrent issue within JsonSchema
+                delay(1.milliseconds)
+                val result = schema.validate(target, OutputCollector.Companion.flag())
+                result.valid.shouldBeTrue()
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}