[GO] Add support for model name mapping for go (#17023)

* Add support for model name mapping for go

Signed-off-by: Aidan Jensen <aidan@artificial.com>

* Add model name and filename tests

Signed-off-by: Aidan <aidan@artificial.com>

* Use File.separator to make the test platform agnostic

Signed-off-by: Aidan <aidan@artificial.com>

---------

Signed-off-by: Aidan Jensen <aidan@artificial.com>
Signed-off-by: Aidan <aidan@artificial.com>

Author: aidandj

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractGoCodegen.java

@@ -280,6 +280,10 @@ protected boolean isReservedFilename(String name) {
 
     @Override
     public String toModelFilename(String name) {
+        // Obtain the model name from modelNameMapping directly if provided
+        if (modelNameMapping.containsKey(name)) {
+            name = modelNameMapping.get(name);
+        }
         name = toModel("model_" + name);
 
         if (isReservedFilename(name)) {
@@ -295,6 +299,11 @@ public String toModel(String name) {
     }
 
     public String toModel(String name, boolean doUnderscore) {
+        // obtain the name from modelNameMapping directly if provided
+        if (modelNameMapping.containsKey(name)) {
+            return modelNameMapping.get(name);
+        }
+
         if (!StringUtils.isEmpty(modelNamePrefix)) {
             name = modelNamePrefix + "_" + name;
         }

modules/openapi-generator/src/test/java/org/openapitools/codegen/go/GoModelTest.java

@@ -30,6 +30,8 @@
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
 
+import java.io.File;
+
 @SuppressWarnings("static-method")
 public class GoModelTest {
 
@@ -298,4 +300,28 @@ public void modelNameTest(String name, String expectedName) {
         Assert.assertEquals(cm.name, name);
         Assert.assertEquals(cm.classname, expectedName);
     }
+
+    @DataProvider(name = "modelMappedNames")
+    public static Object[][] mappedNames() {
+        return new Object[][] {
+            {"mapped", "Remapped", "model_remapped.go"},
+            {"mapped_underscore", "RemappedUnderscore", "model_remapped_underscore.go"},
+        };
+    }
+
+    @Test(dataProvider = "modelMappedNames", description = "map model names")
+    public void modelNameMappingsTest(String name, String expectedName, String expectedFilename) {
+        final Schema model = new Schema();
+        final DefaultCodegen codegen = new GoClientCodegen();
+        codegen.modelNameMapping().put(name, expectedName);
+        OpenAPI openAPI = TestUtils.createOpenAPIWithOneSchema(name, model);
+        codegen.setOpenAPI(openAPI);
+        final CodegenModel cm = codegen.fromModel(name, model);
+
+        final String fn = codegen.modelFilename("model.mustache", name, "");
+        Assert.assertEquals(fn, File.separator + expectedFilename);
+
+        Assert.assertEquals(cm.name, name);
+        Assert.assertEquals(cm.classname, expectedName);
+    }
 }