refactor: extract Docker image and generator name into per-language mixin interfaces

Add RubySpec, PythonSpec, PhpSpec, NodeSpec, JavaSpec, and CSharpSpec
interfaces with default methods for getGeneratorName(), getRuntimeImage(),
and getDockerImage(). Each language's Docker image version is now declared
once instead of being duplicated across every spec.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mridang

src/spec/java/io/github/mridang/codegen/spec/csharp/CSharpBuildSpec.java

@@ -7,7 +7,6 @@
 import org.junit.jupiter.api.Test;
 import org.openapitools.codegen.CodegenConstants;
 import org.testcontainers.junit.jupiter.Testcontainers;
-import org.testcontainers.utility.DockerImageName;
 
 /**
  * Verifies that generated C# code compiles cleanly with the strictest .NET SDK settings. Uses
@@ -16,17 +15,7 @@
  */
 @SuppressWarnings("NewClassNamingConvention")
 @Testcontainers
-public class CSharpBuildSpec extends AbstractIntegrationSpec {
-
-  @Override
-  protected String getGeneratorName() {
-    return "csharp-plus";
-  }
-
-  @Override
-  protected DockerImageName getRuntimeImage() {
-    return DockerImageName.parse("mcr.microsoft.com/dotnet/sdk:9.0");
-  }
+public class CSharpBuildSpec extends AbstractIntegrationSpec implements CSharpSpec {
 
   @Override
   protected String[] getBuildCommands() {

src/spec/java/io/github/mridang/codegen/spec/csharp/CSharpClientSpec.java

@@ -8,21 +8,10 @@
 import java.util.Map;
 import org.openapitools.codegen.CodegenConstants;
 import org.testcontainers.junit.jupiter.Testcontainers;
-import org.testcontainers.utility.DockerImageName;
 
 @SuppressWarnings("NewClassNamingConvention")
 @Testcontainers
-public class CSharpClientSpec extends AbstractClientSpec {
-
-  @Override
-  protected String getGeneratorName() {
-    return "csharp-plus";
-  }
-
-  @Override
-  protected DockerImageName getRuntimeImage() {
-    return DockerImageName.parse("mcr.microsoft.com/dotnet/sdk:9.0");
-  }
+public class CSharpClientSpec extends AbstractClientSpec implements CSharpSpec {
 
   @Override
   protected String[] getBuildCommands() {

src/spec/java/io/github/mridang/codegen/spec/csharp/CSharpFormattingSpec.java

@@ -8,25 +8,14 @@
 import org.junit.jupiter.api.Test;
 import org.openapitools.codegen.CodegenConstants;
 import org.testcontainers.junit.jupiter.Testcontainers;
-import org.testcontainers.utility.DockerImageName;
 
 /**
  * Verifies that generated C# code is already properly formatted according to
  * CSharpier. If this test fails, the C# templates need to be fixed.
  */
 @SuppressWarnings("NewClassNamingConvention")
 @Testcontainers
-public class CSharpFormattingSpec extends AbstractFormattingSpec {
-
-  @Override
-  protected String getGeneratorName() {
-    return "csharp-plus";
-  }
-
-  @Override
-  protected DockerImageName getRuntimeImage() {
-    return DockerImageName.parse("mcr.microsoft.com/dotnet/sdk:9.0");
-  }
+public class CSharpFormattingSpec extends AbstractFormattingSpec implements CSharpSpec {
 
   @Override
   protected String[] getBuildCommands() {

src/spec/java/io/github/mridang/codegen/spec/csharp/CSharpReservedWordsSpec.java

@@ -3,12 +3,7 @@
 import io.github.mridang.codegen.spec.AbstractReservedWordsSpec;
 
 @SuppressWarnings("NewClassNamingConvention")
-class CSharpReservedWordsSpec extends AbstractReservedWordsSpec {
-
-  @Override
-  protected String getDockerImage() {
-    return "mcr.microsoft.com/dotnet/sdk:9.0";
-  }
+class CSharpReservedWordsSpec extends AbstractReservedWordsSpec implements CSharpSpec {
 
   @Override
   protected String getDumpScriptResource() {

src/spec/java/io/github/mridang/codegen/spec/csharp/CSharpSpec.java

@@ -0,0 +1,18 @@
+package io.github.mridang.codegen.spec.csharp;
+
+import org.testcontainers.utility.DockerImageName;
+
+interface CSharpSpec {
+
+  default String getGeneratorName() {
+    return "csharp-plus";
+  }
+
+  default DockerImageName getRuntimeImage() {
+    return DockerImageName.parse("mcr.microsoft.com/dotnet/sdk:9.0");
+  }
+
+  default String getDockerImage() {
+    return "mcr.microsoft.com/dotnet/sdk:9.0";
+  }
+}

src/spec/java/io/github/mridang/codegen/spec/csharp/CSharpStaticAnalysisSpec.java

@@ -7,7 +7,6 @@
 import org.junit.jupiter.api.Test;
 import org.openapitools.codegen.CodegenConstants;
 import org.testcontainers.junit.jupiter.Testcontainers;
-import org.testcontainers.utility.DockerImageName;
 
 /**
  * Verifies that generated C# code passes Roslyn static analysis. Uses dotnet build with warnings as
@@ -16,17 +15,7 @@
  */
 @SuppressWarnings("NewClassNamingConvention")
 @Testcontainers
-public class CSharpStaticAnalysisSpec extends AbstractIntegrationSpec {
-
-  @Override
-  protected String getGeneratorName() {
-    return "csharp-plus";
-  }
-
-  @Override
-  protected DockerImageName getRuntimeImage() {
-    return DockerImageName.parse("mcr.microsoft.com/dotnet/sdk:9.0");
-  }
+public class CSharpStaticAnalysisSpec extends AbstractIntegrationSpec implements CSharpSpec {
 
   @Override
   protected String[] getBuildCommands() {

src/spec/java/io/github/mridang/codegen/spec/java/JavaBuildSpec.java

@@ -12,7 +12,6 @@
 import org.junit.jupiter.api.Test;
 import org.openapitools.codegen.CodegenConstants;
 import org.testcontainers.junit.jupiter.Testcontainers;
-import org.testcontainers.utility.DockerImageName;
 
 /**
  * Verifies that generated Java code compiles cleanly under Error Prone and NullAway with zero
@@ -21,22 +20,12 @@
  */
 @SuppressWarnings("NewClassNamingConvention")
 @Testcontainers
-public class JavaBuildSpec extends AbstractIntegrationSpec {
+public class JavaBuildSpec extends AbstractIntegrationSpec implements JavaSpec {
 
   private static final String PACKAGE_NAME = "com.example.petstore";
   private static final Path TEST_PROJECT_PATH =
       Paths.get("src/spec/resources/testprojects/javatest");
 
-  @Override
-  protected String getGeneratorName() {
-    return "java-plus";
-  }
-
-  @Override
-  protected DockerImageName getRuntimeImage() {
-    return DockerImageName.parse("maven:3.9-eclipse-temurin-21");
-  }
-
   @Override
   protected String[] getBuildCommands() {
     return new String[] {"mvn compile -B"};

src/spec/java/io/github/mridang/codegen/spec/java/JavaClientSpec.java

@@ -8,24 +8,13 @@
 import java.util.Map;
 import org.openapitools.codegen.CodegenConstants;
 import org.testcontainers.junit.jupiter.Testcontainers;
-import org.testcontainers.utility.DockerImageName;
 
 @SuppressWarnings("NewClassNamingConvention")
 @Testcontainers
-public class JavaClientSpec extends AbstractClientSpec {
+public class JavaClientSpec extends AbstractClientSpec implements JavaSpec {
 
   private static final String PACKAGE_NAME = "com.example.petstore";
 
-  @Override
-  protected String getGeneratorName() {
-    return "java-plus";
-  }
-
-  @Override
-  protected DockerImageName getRuntimeImage() {
-    return DockerImageName.parse("maven:3.9-eclipse-temurin-21");
-  }
-
   @Override
   protected String[] getBuildCommands() {
     return new String[] {

src/spec/java/io/github/mridang/codegen/spec/java/JavaFormattingSpec.java

@@ -7,28 +7,17 @@
 import org.junit.jupiter.api.Test;
 import org.openapitools.codegen.CodegenConstants;
 import org.testcontainers.junit.jupiter.Testcontainers;
-import org.testcontainers.utility.DockerImageName;
 
 /**
  * Verifies that generated Java code is already properly formatted according to google-java-format.
  * If this test fails, the Java templates need to be fixed.
  */
 @SuppressWarnings("NewClassNamingConvention")
 @Testcontainers
-public class JavaFormattingSpec extends AbstractFormattingSpec {
+public class JavaFormattingSpec extends AbstractFormattingSpec implements JavaSpec {
 
   private static final String PACKAGE_NAME = "com.example.petstore";
 
-  @Override
-  protected String getGeneratorName() {
-    return "java-plus";
-  }
-
-  @Override
-  protected DockerImageName getRuntimeImage() {
-    return DockerImageName.parse("maven:3.9-eclipse-temurin-21");
-  }
-
   @Override
   protected String[] getBuildCommands() {
     return new String[] {"mvn fmt:check -B"};

src/spec/java/io/github/mridang/codegen/spec/java/JavaReservedWordsSpec.java

@@ -3,12 +3,7 @@
 import io.github.mridang.codegen.spec.AbstractReservedWordsSpec;
 
 @SuppressWarnings("NewClassNamingConvention")
-class JavaReservedWordsSpec extends AbstractReservedWordsSpec {
-
-  @Override
-  protected String getDockerImage() {
-    return "eclipse-temurin:17-jdk-jammy";
-  }
+class JavaReservedWordsSpec extends AbstractReservedWordsSpec implements JavaSpec {
 
   @Override
   protected String getDumpScriptResource() {