chef

Chef::Mixin::WhyRun::ResourceRequirements#assert

Define a new Assertion.

Takes a list of action names for which the assertion should be made.
==== Examples:
A File provider that requires the parent directory to exist:

  assert(:create, :create_if_missing) do |a|
    parent_dir = File.basename(@new_resource.path)
    a.assertion { ::File.directory?(parent_dir) }
    a.failure_message(Exceptions::ParentDirectoryDoesNotExist,
                      "Can't create file #{@new_resource.path}: parent directory #{parent_dir} doesn't exist")
    a.why_run("assuming parent directory #{parent_dir} would have been previously created"
  end

A service provider that requires the init script to exist:

  assert(:start, :restart) do |a|
    a.assertion { ::File.exist?(@new_resource.init_script) }
    a.failure_message(Exceptions::MissingInitScript,
                      "Can't check status of #{@new_resource}: init script #{@new_resource.init_script} is missing")
    a.why_run("Assuming init script would have been created and service is stopped") do
      @current_resource.status(:stopped)
    end
  end

A File provider that will error out if you don't have permissions do
delete the file, *even in why run mode*:

  assert(:delete) do |a|
    a.assertion { ::File.writable?(@new_resource.path) }
    a.failure_message(Exceptions::InsufficientPrivileges,
                      "You don't have sufficient privileges to delete #{@new_resource.path}")
  end

A Template provider that will prevent action execution but continue the run in
whyrun mode if the template source is not available.
  assert(:create, :create_if_missing) do |a|
    a.assertion { File::exist?(@new_resource.source) }
    a.failure_message Chef::Exceptions::TemplateError, "Template #{@new_resource.source} could not be found exist."
    a.whyrun "Template source #{@new_resource.source} does not exist. Assuming it would have been created."
    a.block_action!
  end

  assert(:delete) do |a|
    a.assertion { ::File.writable?(@new_resource.path) }
    a.failure_message(Exceptions::InsufficientPrivileges,
                      "You don't have sufficient privileges to delete #{@new_resource.path}")
  end

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