Add test for duration-constant (#2379)

Add tests for duration-constant as the first step to fix
#1901

---------

Co-authored-by: Pan Shao <[email protected]>

Author: pshao25

.chronus/changes/durationConstant-2025-2-13-16-38-29.md

@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@azure-tools/azure-http-specs"
+---
+
+Add test for duration-constant format

packages/azure-http-specs/spec-summary.md

@@ -722,6 +722,19 @@ Expected response body:
 }
 ```
 
+### Azure_Encode_Duration_durationConstant
+
+- Endpoint: `put /azure/encode/duration/duration-constant`
+
+Test case for azure specific encoding. SDK should generate correct serialization format according to the set encoding.
+Expected request body:
+
+```json
+{
+  "input": "1.02:59:59.5000000"
+}
+```
+
 ### Azure_Example_Basic
 
 - Endpoint: `post /azure/example/basic/basic`

packages/azure-http-specs/specs/azure/encode/duration/main.tsp

@@ -0,0 +1,33 @@
+import "@typespec/http";
+import "@typespec/spector";
+import "@azure-tools/typespec-client-generator-core";
+
+using TypeSpec.Http;
+using global.Azure.ClientGenerator.Core;
+using Spector;
+
+@doc("Test for azure related encode decorator.")
+@scenarioService("/azure/encode/duration")
+namespace _Specs_.Azure.Encode.Duration;
+
+@@clientNamespace(_Specs_.Azure.Encode.Duration, "azure.encode.duration", "java");
+
+model DurationModel {
+  @encode("duration-constant")
+  input: duration;
+}
+
+@scenario
+@scenarioDoc("""
+  Test case for azure specific encoding. SDK should generate correct serialization format according to the set encoding.
+  Expected request body:
+  ```json
+  {
+    "input": "1.02:59:59.5000000"
+  }
+  ```
+  """)
+@doc("Test duration with azure specific encoding.")
+@put
+@route("/duration-constant")
+op durationConstant(@body body: DurationModel): NoContentResponse;

packages/azure-http-specs/specs/azure/encode/duration/mockapi.ts

@@ -0,0 +1,19 @@
+import { passOnSuccess, ScenarioMockApi } from "@typespec/spec-api";
+
+export const Scenarios: Record<string, ScenarioMockApi> = {};
+
+Scenarios.Azure_Encode_Duration_durationConstant = passOnSuccess([
+  {
+    uri: "/azure/encode/duration/duration-constant",
+    method: "put",
+    request: {
+      body: {
+        input: "1.02:59:59.5000000",
+      },
+    },
+    response: {
+      status: 204,
+    },
+    kind: "MockApiDefinition",
+  },
+]);