Add unit test for pattern replace char filter analyzer

java-client/src/test/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilterTest.java

@@ -0,0 +1,53 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.client.opensearch._types.analysis;
+
+import static org.junit.Assert.assertEquals;
+
+import jakarta.json.stream.JsonParser;
+import java.io.StringReader;
+import org.junit.Test;
+import org.opensearch.client.json.jackson.JacksonJsonpMapper;
+
+public class PatternReplaceCharFilterTest {
+    @Test
+    public void testCreatePatternReplaceCharFilter() {
+        PatternReplaceCharFilter patternReplaceCharFilter = new PatternReplaceCharFilter.Builder().pattern("pattern")
+            .replacement("replacement")
+            .build();
+        assertEquals("pattern", patternReplaceCharFilter.pattern());
+        assertEquals("replacement", patternReplaceCharFilter.replacement());
+    }
+
+    @Test
+    public void testCreatePatternReplaceCharFilterWithFlags() {
+        PatternReplaceCharFilter patternReplaceCharFilter = new PatternReplaceCharFilter.Builder().pattern("pattern")
+            .replacement("replacement")
+            .flags("flags")
+            .build();
+        assertEquals("pattern", patternReplaceCharFilter.pattern());
+        assertEquals("replacement", patternReplaceCharFilter.replacement());
+        assertEquals("flags", patternReplaceCharFilter.flags());
+    }
+
+    @Test
+    public void testDeserializePatternReplaceCharFilter() {
+        String jsonString =
+            "{\"type\": \"pattern_replace\", \"pattern\": \"pattern\", \"replacement\": \"replacement\", \"flags\": \"flags\"}";
+
+        StringReader reader = new StringReader(jsonString);
+        JacksonJsonpMapper mapper = new JacksonJsonpMapper();
+        JsonParser parser = mapper.jsonProvider().createParser(reader);
+
+        PatternReplaceCharFilter patternReplaceCharFilter = PatternReplaceCharFilter._DESERIALIZER.deserialize(parser, mapper);
+        assertEquals("pattern", patternReplaceCharFilter.pattern());
+        assertEquals("replacement", patternReplaceCharFilter.replacement());
+        assertEquals("flags", patternReplaceCharFilter.flags());
+    }
+}