Debugging in Inferno

Debug Gem

Debugging using the debug gem is available if running Inferno using a local Ruby installation. The debug gem allows users to set a breakpoint within a test’s run block to debug test behavior.

To use the debug gem:

Add require 'debug/open_nonstop' and debugger to set a breakpoint.
Run your tests until the breakpoint is reached.
In a separate terminal window, run bundle exec rdbg -A to access the debugger console.
Use debug commands, which can be found here.

Example

We first add the require 'debug/open_nonstop' and debugger to set a breakpoint. We’ve added these to lines 9 & 10 in the example test below.

module InfernoTemplate
  class PatientGroup < Inferno::TestGroup
    ...
    test do
      ...
      run do
        fhir_read(:patient, patient_id, name: :patient)

        require 'debug/open_nonstop'
       debugger

       assert_response_status(200)
       assert_resource_type(:patient)
       assert resource.id == patient_id,
             "Requested resource with id #{patient_id}, received resource with id #{resource.id}"
     end
   end
 end
end

We then run the tests until the breakpoint is reached. Then we connect to the debugger console.

ᐅ bundle exec rdbg -A
DEBUGGER (client): Connected. PID:22112, $0:sidekiq 6.5.7  [0 of 10 busy]

[18, 27] in ~/code/inferno-template/lib/inferno_template/patient_group.rb
    18|
    19|       run do
    20|         fhir_read(:patient, patient_id, name: :patient)
    21|
    22|         require 'debug/open_nonstop'
=>  23|         debugger
    24|
    25|         assert_response_status(200)
    26|         assert_resource_type(:patient)
    27|         assert resource.id == patient_id,

Now you can get information about the current object

(ruby:remote) self.id
"test_suite_template-patient_group-Test01"
(ruby:remote) self.title
"Server returns requested Patient resource from the Patient read interaction"

As well as the values of currently defined variables.

(rdbg:remote) inputs
[:patient_id, :url, :credentials]
(ruby:remote) patient_id
"85"
(rdbg:remote) url
"https://inferno.healthit.gov/reference-server/r4"

You can also look at available methods and instance variables of a given object, like request

(rdbg:remote) ls request
Inferno::Entities::Request
  created_at        created_at=  direction     direction=     headers          headers=          id        id=         index          index=          name             name=
  query_parameters  request      request_body  request_body=  request_header   request_headers   resource  response    response_body  response_body=  response_header  response_headers
  result_id         result_id=   status        status=        test_session_id  test_session_id=  to_hash   updated_at  updated_at=    url             url=             verb
  verb=
instance variables: @created_at  @direction  @headers  @id  @index  @name  @request_body  @response_body  @result_id  @status  @test_session_id  @updated_at  @url  @verb

And then use that as a reference to get additional information:

(ruby:remote) request.status
200
(ruby:remote) request.response_body
"{\n  \"resourceType\": \"Patient\" ... }"

There are a lot more commands available than just the ones stated above. You can always type help for the list of all commands, or help [COMMAND] for information about a specific command.

Interactive Console

A local Ruby installation allows you to use pry to explore and experiment with your tests using the inferno console command. Pry is an alternative to the standard Interactive Ruby (IRB) shell that includes syntax highlighting, runtime invocation, source & documentation browsing, and more. It is a helpful tool for debugging the environment generally, as opposed to using the debug gem to review the environment at a specific breakpoint while running the system.

For example, I can look at the Suite class that is defined in the Inferno Template by default (lib/inferno_template.rb) and set it to the variable suite.

ᐅ bundle exec inferno console
[1] pry(main)> suite = InfernoTemplate::Suite
=> [#<InfernoTemplate::Suite @id="test_suite_template", @title="Inferno Test Suite Template">]

And then use that variable to see what groups will be run in the suite, which I see are the Capability Statement and Patient Tests.

[2] pry(main)> suite.groups
=> [#<Inferno::Entities::TestGroup @id="test_suite_template-capability_statement", @short_id="1", @title="Capability Statement">,
 #<InfernoTemplate::PatientGroup @id="test_suite_template-patient_group", @short_id="2", @title="Patient  Tests">]

I can also even see which test will be run first.

[3] pry(main)> suite.groups.first.tests
=> [#<Inferno::Entities::Test @id="test_suite_template-capability_statement-capability_statement_read", @short_id="1.01", @title="Read CapabilityStatement">]