Adds support for mirroring mock responses. Closes #1384

[waldekmastykarz]

Adds support for mirroring mock responses. Closes #1384

Test:

devproxyrc.json

{
  "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v1.1.0/rc.schema.json",
  "plugins": [
    {
      "name": "GraphMockResponsePlugin",
      "enabled": true,
      "pluginPath": "~appFolder/plugins/DevProxy.Plugins.dll",
      "configSection": "mocksPlugin"
    }
  ],
  "urlsToWatch": [
    "https://graph.microsoft.com/v1.0/users*"
  ],
  "mocksPlugin": {
    "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v1.1.0/mockresponseplugin.schema.json",
    "mocksFile": "mocks.json"
  },
  "asSystemProxy": false
}

mocks.json

{
  "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v1.1.0/mockresponseplugin.mocksfile.schema.json",
  "mocks": [
    {
      "request": {
        "url": "https://graph.microsoft.com/v1.0/users",
        "method": "POST"
      },
      "response": {
        "statusCode": 201,
        "body": {
          "@odata.context": "https://graph.microsoft.com/v1.0/$metadata#users/$entity",
          "id": "12345678-1234-1234-1234-123456789abc",
          "businessPhones": "@request.body.businessPhones",
          "displayName": "@request.body.displayName",
          "givenName": "@request.body.givenName",
          "jobTitle": "@request.body.jobTitle",
          "mail": "@request.body.mail",
          "mobilePhone": "@request.body.mobilePhone",
          "officeLocation": "@request.body.officeLocation",
          "preferredLanguage": "@request.body.preferredLanguage",
          "surname": "@request.body.surname",
          "userPrincipalName": "@request.body.userPrincipalName",
          "accountEnabled": "@request.body.accountEnabled",
          "createdDateTime": "2024-01-15T10:30:00Z",
          "department": "@request.body.department",
          "companyName": "@request.body.companyName",
          "city": "@request.body.city",
          "country": "@request.body.country",
          "postalCode": "@request.body.postalCode",
          "state": "@request.body.state",
          "streetAddress": "@request.body.streetAddress",
          "usageLocation": "@request.body.usageLocation"
        },
        "headers": [
          {
            "name": "Content-Type",
            "value": "application/json; odata.metadata=minimal"
          },
          {
            "name": "Location",
            "value": "https://graph.microsoft.com/v1.0/users/12345678-1234-1234-1234-123456789abc"
          },
          {
            "name": "OData-Version",
            "value": "4.0"
          }
        ]
      }
    }
  ]
}

curl:

ccurl -ikx http://127.0.0.1:8000 -X POST https://graph.microsoft.com/v1.0/users \
  -H "Content-Type: application/json" \
  -d '{
    "displayName": "Jane Smith",
    "userPrincipalName": "jane.smith@contoso.com",
    "accountEnabled": true,
    "givenName": "Jane",
    "surname": "Smith",
    "jobTitle": "Product Manager"
  }'

response:

HTTP/1.1 200 Connection Established
Content-Length: 0

HTTP/1.1 201 Created
Cache-Control: no-store
x-ms-ags-diagnostic: 
Strict-Transport-Security: 
request-id: d28ce889-febd-4c2b-a8b7-0a83e2531467
client-request-id: d28ce889-febd-4c2b-a8b7-0a83e2531467
Date: 9/10/2025 10:28:35?AM
Content-Type: application/json; odata.metadata=minimal
Location: https://graph.microsoft.com/v1.0/users/12345678-1234-1234-1234-123456789abc
OData-Version: 4.0
Content-Length: 648

{
  "@odata.context": "https://graph.microsoft.com/v1.0/$metadata#users/$entity",
  "id": "12345678-1234-1234-1234-123456789abc",
  "businessPhones": null,
  "displayName": "Jane Smith",
  "givenName": "Jane",
  "jobTitle": "Product Manager",
  "mail": null,
  "mobilePhone": null,
  "officeLocation": null,
  "preferredLanguage": null,
  "surname": "Smith",
  "userPrincipalName": "jane.smith@contoso.com",
  "accountEnabled": true,
  "createdDateTime": "2024-01-15T10:30:00Z",
  "department": null,
  "companyName": null,
  "city": null,
  "country": null,
  "postalCode": null,
  "state": null,
  "streetAddress": null,
  "usageLocation": null
}

[Copilot]

Pull Request Overview

This PR adds support for mirroring mock responses by allowing placeholder values in mock response bodies to be replaced with actual values from the incoming request body. The feature enables dynamic mock responses where values like @request.body.displayName in the mock configuration are replaced with the corresponding values from the request.

Key changes:

• Adds placeholder replacement functionality for mock response bodies using @request.body.* syntax
• Implements recursive JSON traversal to handle nested objects and arrays in mock responses
• Provides safe type conversion for various JSON value types (strings, numbers, booleans)