diff --git a/src/test/java/org/opensearch/neuralsearch/processor/chunker/FixedTokenLengthChunkerTests.java b/src/test/java/org/opensearch/neuralsearch/processor/chunker/FixedTokenLengthChunkerTests.java
index 3b544991d..c45de1159 100644
--- a/src/test/java/org/opensearch/neuralsearch/processor/chunker/FixedTokenLengthChunkerTests.java
+++ b/src/test/java/org/opensearch/neuralsearch/processor/chunker/FixedTokenLengthChunkerTests.java
@@ -1,2 +1,142 @@
-package org.opensearch.neuralsearch.processor.chunker;public class FixedTokenLengthChunkerTests {
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.opensearch.neuralsearch.processor.chunker;
+
+import lombok.SneakyThrows;
+import org.apache.lucene.tests.analysis.MockTokenizer;
+import org.junit.Before;
+import org.opensearch.common.settings.Settings;
+import org.opensearch.env.Environment;
+import org.opensearch.env.TestEnvironment;
+import org.opensearch.index.analysis.TokenizerFactory;
+import org.opensearch.index.analysis.AnalysisRegistry;
+import org.opensearch.indices.analysis.AnalysisModule;
+import org.opensearch.plugins.AnalysisPlugin;
+import org.opensearch.test.OpenSearchTestCase;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static java.util.Collections.singletonList;
+import static java.util.Collections.singletonMap;
+import static org.opensearch.neuralsearch.processor.chunker.FixedTokenLengthChunker.TOKEN_LIMIT;
+import static org.opensearch.neuralsearch.processor.chunker.FixedTokenLengthChunker.OVERLAP_RATE;
+import static org.opensearch.neuralsearch.processor.chunker.FixedTokenLengthChunker.TOKENIZER;
+
+public class FixedTokenLengthChunkerTests extends OpenSearchTestCase {
+
+    private FixedTokenLengthChunker FixedTokenLengthChunker;
+
+    @Before
+    @SneakyThrows
+    public void setup() {
+        Settings settings = Settings.builder().put(Environment.PATH_HOME_SETTING.getKey(), createTempDir().toString()).build();
+        Environment environment = TestEnvironment.newEnvironment(settings);
+
+        AnalysisPlugin plugin = new AnalysisPlugin() {
+
+            @Override
+            public Map<String, AnalysisModule.AnalysisProvider<TokenizerFactory>> getTokenizers() {
+                return singletonMap(
+                    "keyword",
+                    (indexSettings, environment, name, settings) -> TokenizerFactory.newFactory(
+                        name,
+                        () -> new MockTokenizer(MockTokenizer.KEYWORD, false)
+                    )
+                );
+            }
+        };
+        AnalysisRegistry analysisRegistry = new AnalysisModule(environment, singletonList(plugin)).getAnalysisRegistry();
+        FixedTokenLengthChunker = new FixedTokenLengthChunker(analysisRegistry);
+    }
+
+    public void testValidateParameters_whenNoParams_thenSuccessful() {
+        Map<String, Object> parameters = new HashMap<>();
+        ;
+        FixedTokenLengthChunker.validateParameters(parameters);
+    }
+
+    public void testValidateParameters_whenIllegalTokenLimitType_thenFail() {
+        Map<String, Object> parameters = new HashMap<>();
+        parameters.put(TOKEN_LIMIT, "invalid token limit");
+        IllegalArgumentException illegalArgumentException = assertThrows(
+            IllegalArgumentException.class,
+            () -> FixedTokenLengthChunker.validateParameters(parameters)
+        );
+        assertEquals("fixed length parameter [token_limit] cannot be cast to [java.lang.Number]", illegalArgumentException.getMessage());
+    }
+
+    public void testValidateParameters_whenIllegalTokenLimitValue_thenFail() {
+        Map<String, Object> parameters = new HashMap<>();
+        parameters.put(TOKEN_LIMIT, -1);
+        IllegalArgumentException illegalArgumentException = assertThrows(
+            IllegalArgumentException.class,
+            () -> FixedTokenLengthChunker.validateParameters(parameters)
+        );
+        assertEquals("fixed length parameter [token_limit] must be positive", illegalArgumentException.getMessage());
+    }
+
+    public void testValidateParameters_whenIllegalOverlapRateType_thenFail() {
+        Map<String, Object> parameters = new HashMap<>();
+        parameters.put(OVERLAP_RATE, "invalid overlap rate");
+        IllegalArgumentException illegalArgumentException = assertThrows(
+            IllegalArgumentException.class,
+            () -> FixedTokenLengthChunker.validateParameters(parameters)
+        );
+        assertEquals("fixed length parameter [overlap_rate] cannot be cast to [java.lang.Number]", illegalArgumentException.getMessage());
+    }
+
+    public void testValidateParameters_whenIllegalOverlapRateValue_thenFail() {
+        Map<String, Object> parameters = new HashMap<>();
+        parameters.put(OVERLAP_RATE, 1.0);
+        IllegalArgumentException illegalArgumentException = assertThrows(
+            IllegalArgumentException.class,
+            () -> FixedTokenLengthChunker.validateParameters(parameters)
+        );
+        assertEquals(
+            "fixed length parameter [overlap_rate] must be between 0 and 1, 1 is not included.",
+            illegalArgumentException.getMessage()
+        );
+    }
+
+    public void testValidateParameters_whenIllegalTokenizerType_thenFail() {
+        Map<String, Object> parameters = new HashMap<>();
+        parameters.put(TOKENIZER, 111);
+        IllegalArgumentException illegalArgumentException = assertThrows(
+            IllegalArgumentException.class,
+            () -> FixedTokenLengthChunker.validateParameters(parameters)
+        );
+        assertEquals("fixed length parameter [tokenizer] cannot be cast to [java.lang.String]", illegalArgumentException.getMessage());
+    }
+
+    public void testChunk_withTokenLimit_10() {
+        Map<String, Object> parameters = new HashMap<>();
+        parameters.put(TOKEN_LIMIT, 10);
+        String content =
+            "This is an example document to be chunked. The document contains a single paragraph, two sentences and 24 tokens by standard tokenizer in OpenSearch.";
+        List<String> passages = FixedTokenLengthChunker.chunk(content, parameters);
+        List<String> expectedPassages = new ArrayList<>();
+        expectedPassages.add("This is an example document to be chunked The document");
+        expectedPassages.add("The document contains a single paragraph two sentences and 24");
+        expectedPassages.add("and 24 tokens by standard tokenizer in OpenSearch");
+        assertEquals(expectedPassages, passages);
+    }
+
+    public void testChunk_withTokenLimit_20() {
+        Map<String, Object> parameters = new HashMap<>();
+        parameters.put(TOKEN_LIMIT, 20);
+        String content =
+            "This is an example document to be chunked. The document contains a single paragraph, two sentences and 24 tokens by standard tokenizer in OpenSearch.";
+        List<String> passages = FixedTokenLengthChunker.chunk(content, parameters);
+        List<String> expectedPassages = new ArrayList<>();
+        expectedPassages.add(
+            "This is an example document to be chunked The document contains a single paragraph two sentences and 24 tokens by"
+        );
+        expectedPassages.add("and 24 tokens by standard tokenizer in OpenSearch");
+        assertEquals(expectedPassages, passages);
+    }
 }