diff --git a/retrofit-response-type-keeper/build.gradle b/retrofit-response-type-keeper/build.gradle
index c9015f23f0..00fd0c6d26 100644
--- a/retrofit-response-type-keeper/build.gradle
+++ b/retrofit-response-type-keeper/build.gradle
@@ -11,5 +11,6 @@ dependencies {
   testImplementation libs.junit
   testImplementation libs.compileTesting
   testImplementation libs.truth
+  testImplementation libs.testParameterInjector
   testImplementation projects.retrofit
 }
diff --git a/retrofit-response-type-keeper/src/test/kotlin/retrofit2/keeper/RetrofitResponseTypeKeepProcessorTest.kt b/retrofit-response-type-keeper/src/test/kotlin/retrofit2/keeper/RetrofitResponseTypeKeepProcessorTest.kt
index 23cc38bb9c..6c97f063c4 100644
--- a/retrofit-response-type-keeper/src/test/kotlin/retrofit2/keeper/RetrofitResponseTypeKeepProcessorTest.kt
+++ b/retrofit-response-type-keeper/src/test/kotlin/retrofit2/keeper/RetrofitResponseTypeKeepProcessorTest.kt
@@ -18,86 +18,29 @@ package retrofit2.keeper
 import com.google.common.truth.Truth.assertAbout
 import com.google.testing.compile.JavaFileObjects
 import com.google.testing.compile.JavaSourceSubjectFactory.javaSource
+import com.google.testing.junit.testparameterinjector.TestParameter
+import com.google.testing.junit.testparameterinjector.TestParameterInjector
 import java.nio.charset.StandardCharsets.UTF_8
+import java.nio.file.NoSuchFileException
 import javax.tools.StandardLocation.CLASS_OUTPUT
+import kotlin.io.path.readText
+import kotlin.io.path.toPath
 import org.junit.Test
+import org.junit.runner.RunWith
 
+@RunWith(TestParameterInjector::class)
 class RetrofitResponseTypeKeepProcessorTest {
   @Test
-  fun allHttpMethods() {
+  fun process(
+    @TestParameter(
+      "all-http-methods",
+      "nesting",
+      "kotlin-suspend",
+    ) name: String
+  ) {
     val service = JavaFileObjects.forSourceString(
       "test.Service",
-      """
-      package test;
-      import retrofit2.*;
-      import retrofit2.http.*;
-
-      class DeleteUser {}
-      class GetUser {}
-      class HeadUser {}
-      class HttpUser {}
-      class OptionsUser {}
-      class PatchUser {}
-      class PostUser {}
-      class PutUser {}
-
-      interface Service {
-        @DELETE("/") Call<DeleteUser> delete();
-        @GET("/") Call<GetUser> get();
-        @HEAD("/") Call<HeadUser> head();
-        @HTTP(method = "CUSTOM", path = "/") Call<HttpUser> http();
-        @OPTIONS("/") Call<OptionsUser> options();
-        @PATCH("/") Call<PatchUser> patch();
-        @POST("/") Call<PostUser> post();
-        @PUT("/") Call<PutUser> put();
-      }
-    """.trimIndent(),
-    )
-
-    assertAbout(javaSource())
-      .that(service)
-      .processedWith(RetrofitResponseTypeKeepProcessor())
-      .compilesWithoutError()
-      .and()
-      .generatesFileNamed(
-        CLASS_OUTPUT,
-        "",
-        "META-INF/proguard/retrofit-response-type-keeper-test.Service.pro",
-      ).withStringContents(
-        UTF_8,
-        """
-        |# test.Service
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class retrofit2.Call
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.DeleteUser
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.GetUser
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.HeadUser
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.HttpUser
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.OptionsUser
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.PatchUser
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.PostUser
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.PutUser
-        |
-        """.trimMargin(),
-      )
-  }
-
-  @Test
-  fun nesting() {
-    val service = JavaFileObjects.forSourceString(
-      "test.Service",
-      """
-      package test;
-      import retrofit2.*;
-      import retrofit2.http.*;
-
-      class One<T> {}
-      class Two<T> {}
-      class Three {}
-
-      interface Service {
-        @GET("/") Call<One<Two<Three>>> get();
-      }
-    """.trimIndent(),
+      readResourceAsText("$name/Service.java"),
     )
 
     assertAbout(javaSource())
@@ -111,52 +54,15 @@ class RetrofitResponseTypeKeepProcessorTest {
         "META-INF/proguard/retrofit-response-type-keeper-test.Service.pro",
       ).withStringContents(
         UTF_8,
-        """
-        |# test.Service
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class retrofit2.Call
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.One
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.Three
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.Two
-        |
-        """.trimMargin(),
+        readResourceAsText("$name/Service.pro"),
       )
   }
 
-  @Test
-  fun kotlinSuspend() {
-    val service = JavaFileObjects.forSourceString(
-      "test.Service",
-      """
-      package test;
-      import kotlin.coroutines.Continuation;
-      import retrofit2.*;
-      import retrofit2.http.*;
-
-      class Body {}
-
-      interface Service {
-        @GET("/") Object get(Continuation<? extends Body> c);
-      }
-    """.trimIndent(),
-    )
-
-    assertAbout(javaSource())
-      .that(service)
-      .processedWith(RetrofitResponseTypeKeepProcessor())
-      .compilesWithoutError()
-      .and()
-      .generatesFileNamed(
-        CLASS_OUTPUT,
-        "",
-        "META-INF/proguard/retrofit-response-type-keeper-test.Service.pro",
-      ).withStringContents(
-        UTF_8,
-        """
-        |# test.Service
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class java.lang.Object
-        |-keep,allowoptimization,allowshrinking,allowobfuscation class test.Body
-        |
-        """.trimMargin(),
-      )
+  private companion object {
+    fun readResourceAsText(name: String): String {
+      val resource = this::class.java.classLoader.getResource(name)
+        ?: throw NoSuchFileException("Resource $name not found.")
+      return resource.toURI().toPath().readText()
+    }
   }
 }
diff --git a/retrofit-response-type-keeper/src/test/resources/all-http-methods/Service.java b/retrofit-response-type-keeper/src/test/resources/all-http-methods/Service.java
new file mode 100644
index 0000000000..93ad79b7b5
--- /dev/null
+++ b/retrofit-response-type-keeper/src/test/resources/all-http-methods/Service.java
@@ -0,0 +1,24 @@
+package test;
+
+import retrofit2.*;
+import retrofit2.http.*;
+
+class DeleteUser {}
+class GetUser {}
+class HeadUser {}
+class HttpUser {}
+class OptionsUser {}
+class PatchUser {}
+class PostUser {}
+class PutUser {}
+
+interface Service {
+  @DELETE("/") Call<DeleteUser> delete();
+  @GET("/") Call<GetUser> get();
+  @HEAD("/") Call<HeadUser> head();
+  @HTTP(method = "CUSTOM", path = "/") Call<HttpUser> http();
+  @OPTIONS("/") Call<OptionsUser> options();
+  @PATCH("/") Call<PatchUser> patch();
+  @POST("/") Call<PostUser> post();
+  @PUT("/") Call<PutUser> put();
+}
diff --git a/retrofit-response-type-keeper/src/test/resources/all-http-methods/Service.pro b/retrofit-response-type-keeper/src/test/resources/all-http-methods/Service.pro
new file mode 100644
index 0000000000..bc42931349
--- /dev/null
+++ b/retrofit-response-type-keeper/src/test/resources/all-http-methods/Service.pro
@@ -0,0 +1,10 @@
+# test.Service
+-keep,allowoptimization,allowshrinking,allowobfuscation class retrofit2.Call
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.DeleteUser
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.GetUser
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.HeadUser
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.HttpUser
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.OptionsUser
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.PatchUser
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.PostUser
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.PutUser
diff --git a/retrofit-response-type-keeper/src/test/resources/kotlin-suspend/Service.java b/retrofit-response-type-keeper/src/test/resources/kotlin-suspend/Service.java
new file mode 100644
index 0000000000..6cd8250020
--- /dev/null
+++ b/retrofit-response-type-keeper/src/test/resources/kotlin-suspend/Service.java
@@ -0,0 +1,11 @@
+package test;
+
+import kotlin.coroutines.Continuation;
+import retrofit2.*;
+import retrofit2.http.*;
+
+class Body {}
+
+interface Service {
+  @GET("/") Object get(Continuation<? extends Body> c);
+}
diff --git a/retrofit-response-type-keeper/src/test/resources/kotlin-suspend/Service.pro b/retrofit-response-type-keeper/src/test/resources/kotlin-suspend/Service.pro
new file mode 100644
index 0000000000..f16efdb512
--- /dev/null
+++ b/retrofit-response-type-keeper/src/test/resources/kotlin-suspend/Service.pro
@@ -0,0 +1,3 @@
+# test.Service
+-keep,allowoptimization,allowshrinking,allowobfuscation class java.lang.Object
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.Body
diff --git a/retrofit-response-type-keeper/src/test/resources/nesting/Service.java b/retrofit-response-type-keeper/src/test/resources/nesting/Service.java
new file mode 100644
index 0000000000..7c4f2e5959
--- /dev/null
+++ b/retrofit-response-type-keeper/src/test/resources/nesting/Service.java
@@ -0,0 +1,12 @@
+package test;
+
+import retrofit2.*;
+import retrofit2.http.*;
+
+class One<T> {}
+class Two<T> {}
+class Three {}
+
+interface Service {
+  @GET("/") Call<One<Two<Three>>> get();
+}
diff --git a/retrofit-response-type-keeper/src/test/resources/nesting/Service.pro b/retrofit-response-type-keeper/src/test/resources/nesting/Service.pro
new file mode 100644
index 0000000000..331a97c51b
--- /dev/null
+++ b/retrofit-response-type-keeper/src/test/resources/nesting/Service.pro
@@ -0,0 +1,5 @@
+# test.Service
+-keep,allowoptimization,allowshrinking,allowobfuscation class retrofit2.Call
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.One
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.Three
+-keep,allowoptimization,allowshrinking,allowobfuscation class test.Two