From be98f801ec3550e60e485862ecd42bdf866e7c42 Mon Sep 17 00:00:00 2001
From: Logan Kennedy <163435909+loggk@users.noreply.github.com>
Date: Sun, 9 Aug 2026 08:50:28 -0700
Subject: [PATCH] Run model tests against both JSON mappers instead of picking
 one at random (#2085)

Signed-off-by: Logan Kennedy <kennedylogan22@gmail.com>
---
 CHANGELOG.md                                  |  1 +
 .../opensearch/model/ModelTestCase.java       | 58 +++++++++----------
 2 files changed, 27 insertions(+), 32 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11621f6a7e..391e8b8b23 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ### Fixed
 - Fix `unitTest` task not running the tests in the `test` source set ([#2074](https://github.com/opensearch-project/opensearch-java/pull/2074))
+- Run model tests against both JSON mappers instead of picking one at random ([#2085](https://github.com/opensearch-project/opensearch-java/pull/2085))
 
 ## [Unreleased 3.x]
 ### Added
diff --git a/java-client/src/test/java/org/opensearch/client/opensearch/model/ModelTestCase.java b/java-client/src/test/java/org/opensearch/client/opensearch/model/ModelTestCase.java
index 51babb7001..e9557fe0a4 100644
--- a/java-client/src/test/java/org/opensearch/client/opensearch/model/ModelTestCase.java
+++ b/java-client/src/test/java/org/opensearch/client/opensearch/model/ModelTestCase.java
@@ -38,51 +38,45 @@
 import java.io.StringReader;
 import java.io.StringWriter;
 import java.lang.reflect.Method;
-import java.util.Random;
+import java.util.Arrays;
+import java.util.Collection;
 import org.junit.Assert;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
 import org.opensearch.client.json.JsonpDeserializer;
 import org.opensearch.client.json.JsonpMapper;
 import org.opensearch.client.json.jackson.JacksonJsonpMapper;
 import org.opensearch.client.json.jsonb.JsonbJsonpMapper;
 
 /**
- * Base class for tests that encode/decode json
+ * Base class for tests that encode/decode json.
+ * Every test is run once per JsonpMapper implementation.
  */
+@RunWith(Parameterized.class)
 public abstract class ModelTestCase extends Assert {
 
-    // Same value for all tests in a test run
-    private static final int RAND = new Random().nextInt(100);
-
-    protected final JsonpMapper mapper;
-
-    private JsonpMapper setupMapper(int rand) {
-        // Randomly choose json-b or jackson
-        if (rand % 2 == 0) {
-            System.out.println("Using a JsonB mapper (rand = " + rand + ").");
-            return new JsonbJsonpMapper() {
-                @Override
-                public boolean ignoreUnknownFields() {
-                    return false;
-                }
-            };
-        } else {
-            System.out.println("Using a Jackson mapper (rand = " + rand + ").");
-            return new JacksonJsonpMapper() {
-                @Override
-                public boolean ignoreUnknownFields() {
-                    return false;
-                }
-            };
-        }
+    @Parameterized.Parameters(name = "{0}")
+    public static Collection<Object[]> mappers() {
+        JsonpMapper jsonb = new JsonbJsonpMapper() {
+            @Override
+            public boolean ignoreUnknownFields() {
+                return false;
+            }
+        };
+        JsonpMapper jackson = new JacksonJsonpMapper() {
+            @Override
+            public boolean ignoreUnknownFields() {
+                return false;
+            }
+        };
+        return Arrays.asList(new Object[] { "json-b", jsonb }, new Object[] { "jackson", jackson });
     }
 
-    protected ModelTestCase() {
-        this(RAND);
-    }
+    @Parameterized.Parameter(0)
+    public String mapperName;
 
-    protected ModelTestCase(int rand) {
-        mapper = setupMapper(rand);
-    }
+    @Parameterized.Parameter(1)
+    public JsonpMapper mapper;
 
     protected <T> String toJson(T value) {
         return toJson(value, mapper);