HTTP Mock Lib

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Content Types ​

Set the Content-Type header for your mocked responses.

Built-in Content Types ​

HTTP Mock Lib provides semantic methods for common content types.

contentTypeJson() ​

apex
HttpMock contentTypeJson()  // application/json

Default content type. Used for JSON responses.

apex
new HttpMock()
  .whenGetOn('/api/users')
  .body('{"users": []}')
  .contentTypeJson()
  .mock();

contentTypePlainText() ​

apex
HttpMock contentTypePlainText()  // text/plain

Plain text responses.

apex
new HttpMock()
  .whenGetOn('/api/status')
  .body('Service is running')
  .contentTypePlainText()
  .mock();

contentTypeHtml() ​

apex
HttpMock contentTypeHtml()  // text/html

HTML responses.

apex
new HttpMock()
  .whenGetOn('/api/page')
  .body('<html><body><h1>Hello</h1></body></html>')
  .contentTypeHtml()
  .mock();

contentTypeCsv() ​

apex
HttpMock contentTypeCsv()  // text/csv

CSV data responses.

apex
new HttpMock()
  .whenGetOn('/api/export/users.csv')
  .body('id,name,email\n1,John,john@example.com\n2,Jane,jane@example.com')
  .contentTypeCsv()
  .header('Content-Disposition', 'attachment; filename="users.csv"')
  .mock();

contentTypeXml() ​

apex
HttpMock contentTypeXml()  // application/xml

XML responses.

apex
new HttpMock()
  .whenGetOn('/api/users')
  .body('<?xml version="1.0"?><users><user id="1">John</user></users>')
  .contentTypeXml()
  .mock();

contentTypePdf() ​

apex
HttpMock contentTypePdf()  // application/pdf

PDF document responses.

apex
Blob pdfData = generatePdfContent();

new HttpMock()
  .whenGetOn('/api/report.pdf')
  .body(pdfData)
  .contentTypePdf()
  .mock();

contentTypeFormUrlencoded() ​

apex
HttpMock contentTypeFormUrlencoded()  // application/x-www-form-urlencoded

Form-encoded data.

apex
new HttpMock()
  .whenPostOn('/api/login')
  .body('username=john&password=secret')
  .contentTypeFormUrlencoded()
  .mock();

Custom Content Type ​

For content types not covered by built-in methods:

apex
HttpMock contentType(String contentType)

Examples:

apex
// YAML
new HttpMock()
  .whenGetOn('/api/config')
  .body('key: value\nlist:\n  - item1\n  - item2')
  .contentType('application/x-yaml')
  .mock();

// Protocol Buffers
new HttpMock()
  .whenGetOn('/api/data')
  .body(protobufBlob)
  .contentType('application/protobuf')
  .mock();

// Custom vendor type
new HttpMock()
  .whenGetOn('/api/custom')
  .body('{"data": {}}')
  .contentType('application/vnd.mycompany.v1+json')
  .mock();

Default Content Type ​

If not specified, HTTP Mock Lib uses application/json:

apex
// These are equivalent:
new HttpMock()
  .whenGetOn('/api/users')
  .body('{"users": []}')
  .mock();

new HttpMock()
  .whenGetOn('/api/users')
  .body('{"users": []}')
  .contentTypeJson()  // Explicitly set
  .mock();

Content Type Reference ​

Content TypeMethodUsage
application/jsoncontentTypeJson()JSON data (default)
text/plaincontentTypePlainText()Plain text
text/htmlcontentTypeHtml()HTML documents
text/csvcontentTypeCsv()CSV data
application/xmlcontentTypeXml()XML data
application/pdfcontentTypePdf()PDF documents
application/x-www-form-urlencodedcontentTypeFormUrlencoded()Form data
CustomcontentType(String)Any MIME type

Examples ​

JSON API Response ​

apex
new HttpMock()
  .whenGetOn('/api/v1/users')
  .body('{"users": [], "total": 0}')
  .contentTypeJson()
  .statusCodeOk()
  .mock();

CSV Export ​

apex
String csvData = 'Name,Email,Status\n' +
                 'John Doe,john@example.com,Active\n' +
                 'Jane Smith,jane@example.com,Active';

new HttpMock()
  .whenGetOn('/api/export')
  .body(csvData)
  .contentTypeCsv()
  .header('Content-Disposition', 'attachment; filename="export.csv"')
  .statusCodeOk()
  .mock();

XML SOAP Response ​

apex
String soapResponse =
  '<?xml version="1.0"?>' +
  '<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">' +
    '<soap:Body>' +
      '<Response>Success</Response>' +
    '</soap:Body>' +
  '</soap:Envelope>';

new HttpMock()
  .whenPostOn('/soap/endpoint')
  .body(soapResponse)
  .contentType('application/soap+xml')
  .statusCodeOk()
  .mock();

Binary File Download ​

apex
Blob fileContent = Blob.valueOf('File content');

new HttpMock()
  .whenGetOn('/api/download/document.pdf')
  .body(fileContent)
  .contentTypePdf()
  .header('Content-Length', String.valueOf(fileContent.size()))
  .header('Content-Disposition', 'attachment; filename="document.pdf"')
  .statusCodeOk()
  .mock();

Best Practices ​

  1. Match Real APIs - Use the same content type as the actual API

  2. Set Explicitly - Even though JSON is default, explicitly set content type for clarity

  3. Use with Headers - Combine with other headers like Content-Disposition for downloads

  4. Validate Format - Ensure your body format matches the content type

Common Patterns ​

API with Multiple Formats ​

apex
// JSON endpoint
new HttpMock()
  .whenGetOn('/api/data?format=json')
  .body('{"data": []}')
  .contentTypeJson()
  .mock();

// XML endpoint
new HttpMock()
  .whenGetOn('/api/data?format=xml')
  .body('<?xml version="1.0"?><data></data>')
  .contentTypeXml()
  .mock();

File Upload Response ​

apex
new HttpMock()
  .whenPostOn('/api/upload')
  .body('{"fileId": "abc123", "url": "https://cdn.example.com/abc123"}')
  .contentTypeJson()
  .statusCodeCreated()
  .header('Location', '/api/files/abc123')
  .mock();

See Also ​