diff --git a/src/integrationTest/kotlin/dev/dnpm/etl/processor/pseudonym/GpasPseudonymGeneratorTest.kt b/src/integrationTest/kotlin/dev/dnpm/etl/processor/pseudonym/GpasPseudonymGeneratorTest.kt
new file mode 100644
index 0000000..da0c55c
--- /dev/null
+++ b/src/integrationTest/kotlin/dev/dnpm/etl/processor/pseudonym/GpasPseudonymGeneratorTest.kt
@@ -0,0 +1,136 @@
+/*
+ * This file is part of ETL-Processor
+ *
+ * Copyright (c) 2024  Comprehensive Cancer Center Mainfranken, Datenintegrationszentrum Philipps-Universität Marburg and Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package dev.dnpm.etl.processor.pseudonym
+
+import dev.dnpm.etl.processor.config.GPasConfigProperties
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import org.springframework.http.HttpHeaders
+import org.springframework.http.HttpMethod
+import org.springframework.http.HttpStatus
+import org.springframework.retry.policy.SimpleRetryPolicy
+import org.springframework.retry.support.RetryTemplateBuilder
+import org.springframework.test.web.client.MockRestServiceServer
+import org.springframework.test.web.client.match.MockRestRequestMatchers.method
+import org.springframework.test.web.client.match.MockRestRequestMatchers.requestTo
+import org.springframework.test.web.client.response.MockRestResponseCreators.withException
+import org.springframework.test.web.client.response.MockRestResponseCreators.withStatus
+import org.springframework.web.client.RestTemplate
+import java.io.IOException
+
+class GpasPseudonymGeneratorTest {
+
+    private lateinit var mockRestServiceServer: MockRestServiceServer
+    private lateinit var generator: GpasPseudonymGenerator
+    private lateinit var restTemplate: RestTemplate
+
+    @BeforeEach
+    fun setup() {
+        val retryTemplate = RetryTemplateBuilder().customPolicy(SimpleRetryPolicy(1)).build()
+        val gPasConfigProperties = GPasConfigProperties(
+            "http://localhost/ttp-fhir/fhir/gpas/\$pseudonymizeAllowCreate",
+            "test",
+            null,
+            null,
+            null
+        )
+
+        this.restTemplate = RestTemplate()
+        this.mockRestServiceServer = MockRestServiceServer.createServer(restTemplate)
+        this.generator = GpasPseudonymGenerator(gPasConfigProperties, retryTemplate, restTemplate)
+    }
+
+    @Test
+    fun shouldReturnExpectedPseudonym() {
+        this.mockRestServiceServer.expect {
+            method(HttpMethod.POST)
+            requestTo("http://localhost/ttp-fhir/fhir/gpas/\$pseudonymizeAllowCreate")
+        }.andRespond {
+            withStatus(HttpStatus.OK).body(getDummyResponseBody("1234", "test", "test1234ABCDEF567890"))
+                .createResponse(it)
+        }
+
+        assertThat(this.generator.generate("ID1234")).isEqualTo("test1234ABCDEF567890")
+    }
+
+    @Test
+    fun shouldThrowExceptionIfGpasNotAvailable() {
+        this.mockRestServiceServer.expect {
+            method(HttpMethod.POST)
+            requestTo("http://localhost/ttp-fhir/fhir/gpas/\$pseudonymizeAllowCreate")
+        }.andRespond {
+            withException(IOException("Simulated IO error")).createResponse(it)
+        }
+
+        assertThrows<PseudonymRequestFailed> { this.generator.generate("ID1234") }
+    }
+
+    @Test
+    fun shouldThrowExceptionIfGpasDoesNotReturn2xxResponse() {
+        this.mockRestServiceServer.expect {
+            method(HttpMethod.POST)
+            requestTo("http://localhost/ttp-fhir/fhir/gpas/\$pseudonymizeAllowCreate")
+        }.andRespond {
+            withStatus(HttpStatus.FOUND)
+                .header(HttpHeaders.LOCATION, "https://localhost/ttp-fhir/fhir/gpas/\$pseudonymizeAllowCreate")
+                .createResponse(it)
+        }
+
+        assertThrows<PseudonymRequestFailed> { this.generator.generate("ID1234") }
+    }
+
+    companion object {
+
+        fun getDummyResponseBody(original: String, target: String, pseudonym: String) = """{
+          "resourceType": "Parameters",
+          "parameter": [
+            {
+              "name": "pseudonym",
+              "part": [
+                {
+                  "name": "original",
+                  "valueIdentifier": {
+                    "system": "https://ths-greifswald.de/gpas",
+                    "value": "$original"
+                  }
+                },
+                {
+                  "name": "target",
+                  "valueIdentifier": {
+                    "system": "https://ths-greifswald.de/gpas",
+                    "value": "$target"
+                  }
+                },
+                {
+                  "name": "pseudonym",
+                  "valueIdentifier": {
+                    "system": "https://ths-greifswald.de/gpas",
+                    "value": "$pseudonym"
+                  }
+                }
+              ]
+            }
+          ]
+        }""".trimIndent()
+
+    }
+}
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