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Test Inputs/Outputs

Table of Contents

  1. Overview
  2. Defining Inputs
    1. Defining Multiple Inputs
  3. Defining Outputs
  4. Handling Complex Objects
  5. Behind the Scenes

Overview

Inputs and outputs provide a structured way to pass information into and out of tests. When a user initiates a test run, a modal is displayed allowing them to provide input values. When multiple tests are being run together, the user is not prompted for inputs which can be populated by the output of a previous test in the run. Currently, all inputs and outputs are stored as strings.

Defining Inputs

The input method defines an input. input can take several arguments, but only the identifier is required:

  • identifier - (required) a name for this input. The input value is available in the run block using this name.
  • title: - a title which is displayed in the UI.
  • description: - a description which is displayed in the UI.
  • type: - controls the type of html input element used in the UI. Currently three possible values:
    • 'text' - (default) a regular input field.
    • 'textarea' - for a text area input field.
    • 'radio' - for a radio button singular selection field.
  • default: - default value for the input.
  • optional: - (default: false) whether the input is optional.
  • options: - possible input option formats based on input type.
    • list_options: - options for input formats that require a list of possible values.
test do
  input :url,
        title: 'FHIR Server Url',
        description: 'The base url for the FHIR server'
        
  run do
    # The input's identifier is :url, so its value is available via `url`
    assert url.start_with?('https'), 'The server must support https'
  end
end

input in the API docs

Defining Multiple Inputs

It is possible to define multiple inputs in a single input call, but not with any of the additional properties listed above.

test do
  input :input1, :input2, :input3, :input4
  ...
end

Defining Outputs

The output method defines an output. It is used in a test’s definition block to define which outputs a test uses, and within a test’s run block to assign a value to an output. Multiple outputs can be defined/assigned at once.

test do
  output :value1
  output :value2, :value3
  
  run do
    output value1: 'ABC'
    output value2: 'DEF',
           value3: 'GHI'
  end
end

test do
  # These inputs will automatically get their values from the previous test's
  # outputs.
  input :value1, :value2, :value3
  ...
end

output for defining outputs in the API docs

output for assigning values to outputs in the API docs

Handling Complex Objects

Since inputs and outputs are all stored as strings, special handling is needed if you want to use them to pass complex objects between tests. This can generally be handled using JSON serialization. Ruby hashes and arrays, as well as FHIR model classes support the to_json method turn the object into a JSON string.

test do
  output :complex_object_json
  
  run do
    ...
    output complex_object_json: hash_or_array_or_fhir_resource.to_json
  end
end

test do
  input :complex_object_json
  
  run do
    assert_valid_json(complex_object_json) # For safety

    complex_object = JSON.parse(complex_object_json)
    ...
  end
end

Behind the Scenes

Inputs and outputs work as a single key-value store scoped to a test session. The main differences between them are that an input’s value can not be changed during a test, and inputs support additional metadata for display in the UI (title, description, etc.). Since inputs and outputs form a single key-value store, a value will be overwritten if multiple tests write to the same output. However, each test result stores the input/output values that were present for that particular test.