fix(csharp): skip mock test examples with empty path parameters (#14879)

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Author: Swimburger

generators/csharp/base/src/context/CsharpTypeMapper.ts

@@ -59,7 +59,8 @@ export class CsharpTypeMapper extends WithGeneration {
                 return property.isOptional ? this.Types.FileParameter.asOptional() : this.Types.FileParameter;
             }
             case "fileArray": {
-                return property.isOptional ? this.Types.FileParameter.asOptional() : this.Types.FileParameter;
+                const listType = this.Collection.list(this.Types.FileParameter);
+                return property.isOptional ? listType.asOptional() : listType;
             }
             default:
                 assertNever(property);

generators/csharp/dynamic-snippets/src/context/DynamicLiteralMapper.ts

@@ -140,6 +140,11 @@ export class DynamicLiteralMapper extends WithGeneration {
         value: unknown;
         fallbackToDefault?: string;
     }): ast.Literal {
+        // When generateLiterals is enabled, inline literal properties use `= new()`
+        // default initializers in the C# model and must not be set in the snippet.
+        if (this.settings.generateLiterals) {
+            return this.csharp.Literal.nop();
+        }
         switch (literal.type) {
             case "boolean": {
                 const bool = this.context.getValueAsBoolean({ value });
@@ -240,6 +245,21 @@ export class DynamicLiteralMapper extends WithGeneration {
     }): ast.Literal {
         switch (named.type) {
             case "alias":
+                // When generateLiterals is enabled and the alias resolves to a literal,
+                // the C# model emits a readonly struct (e.g. `FormatMp3`) instead of a
+                // raw string/bool. Instantiate it with `new TypeName()` rather than
+                // emitting a plain literal value.
+                if (this.settings.generateLiterals && named.typeReference.type === "literal") {
+                    return this.csharp.Literal.reference(
+                        this.csharp.instantiateClass({
+                            classReference: this.csharp.classReference({
+                                origin: named.declaration,
+                                namespace: this.context.getNamespace(named.declaration.fernFilepath)
+                            }),
+                            arguments_: []
+                        })
+                    );
+                }
                 return this.convert({ typeReference: named.typeReference, value, as, fallbackToDefault });
             case "discriminatedUnion":
                 if (this.settings.shouldGeneratedDiscriminatedUnions) {

generators/csharp/dynamic-snippets/src/context/DynamicTypeMapper.ts

@@ -68,6 +68,12 @@ export class DynamicTypeMapper extends WithGeneration {
     private convertNamed({ named }: { named: FernIr.dynamic.NamedType }): ast.Type {
         switch (named.type) {
             case "alias":
+                if (this.settings.generateLiterals && named.typeReference.type === "literal") {
+                    return this.csharp.classReference({
+                        origin: named.declaration,
+                        namespace: this.context.getNamespace(named.declaration.fernFilepath)
+                    });
+                }
                 return this.convert({ typeReference: named.typeReference });
             case "enum":
             case "object":

generators/csharp/sdk/src/generateSdkTests.ts

@@ -30,7 +30,17 @@ function generateMockServerTests({ context }: { context: SdkGeneratorContext }):
             // TODO: support other response body types
             const useableExamples = allExamples.filter((example): example is FernIr.ExampleEndpointCall => {
                 const response = example?.response;
-                return response?.type === "ok" && response.value.type === "body";
+                if (response?.type !== "ok" || response.value.type !== "body") {
+                    return false;
+                }
+                // Skip examples with empty string path parameters. An empty path parameter
+                // causes a URL mismatch: the mock server registers a collapsed path (e.g.
+                // /v0/tools/version/1) while the SDK client sends a double-slash path (e.g.
+                // /v0/tools//version/1), resulting in a 404 from WireMock.
+                if (example != null && hasEmptyPathParameter(example)) {
+                    return false;
+                }
+                return true;
             });
             if (useableExamples.length === 0) {
                 continue;
@@ -49,6 +59,15 @@ function generateMockServerTests({ context }: { context: SdkGeneratorContext }):
     return files;
 }
 
+function hasEmptyPathParameter(example: FernIr.ExampleEndpointCall): boolean {
+    const allPathParams = [
+        ...example.rootPathParameters,
+        ...example.servicePathParameters,
+        ...example.endpointPathParameters
+    ];
+    return allPathParams.some((param) => param.value.jsonExample === "");
+}
+
 function shouldSkipMockServerTestForEndpoint({ endpoint }: { endpoint: FernIr.HttpEndpoint }): boolean {
     const responseBodyType = endpoint.response?.body?.type;
     if (responseBodyType === "fileDownload" || responseBodyType === "streamParameter") {

generators/csharp/sdk/versions.yml

@@ -1,4 +1,26 @@
 # yaml-language-server: $schema=../../../fern-versions-yml.schema.json
+- version: 2.59.5
+  changelogEntry:
+    - summary: |
+        Skip mock server test examples with empty string path parameters. An
+        empty path parameter causes the mock server to register a collapsed URL
+        (e.g. `/v0/tools/version/1`) while the SDK client sends a double-slash
+        URL (e.g. `/v0/tools//version/1`), resulting in a 404 from WireMock.
+      type: fix
+    - summary: |
+        Fix dynamic snippet generation for literal types when `generate-literals`
+        (or `experimental-readonly-constants`) is enabled. Inline literal
+        properties now correctly omit the value (relying on the `= new()`
+        default initializer), and named literal alias types emit `new TypeName()`
+        instead of a raw string, preventing CS0029 compilation errors.
+      type: fix
+    - summary: |
+        Fix file upload request properties declared as `list<file>` generating
+        a single `FileParameter` field instead of `List<FileParameter>`.
+      type: fix
+  createdAt: "2026-04-10"
+  irVersion: 66
+
 - version: 2.59.4
   changelogEntry:
     - summary: |