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DavidSDavidS
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Merge pull request #513 from dmitryilyin/fetch
Add a new function "try_get_value"
2 parents 9352db7 + 823a352 commit 64267eb

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‎README.markdown‎

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@@ -702,6 +702,40 @@ Returns the current Unix epoch time as an integer. For example, `time()` returns
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Converts the argument into bytes, for example "4 kB" becomes "4096". Takes a single string value as an argument. *Type*: rvalue.
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#### `try_get_value`
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*Type*: rvalue.
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Looks up into a complex structure of arrays and hashes and returns a value
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or the default value if nothing was found.
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Key can contain slashes to describe path components. The function will go down
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the structure and try to extract the required value.
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$data = {
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'a' => {
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'b' => [
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'b1',
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'b2',
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'b3',
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]
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}
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}
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$value = try_get_value($data, 'a/b/2', 'not_found', '/')
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=> $value = 'b3'
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a -> first hash key
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b -> second hash key
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2 -> array index starting with 0
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not_found -> (optional) will be returned if there is no value or the path did not match. Defaults to nil.
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/ -> (optional) path delimiter. Defaults to '/'.
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In addition to the required "key" argument, "try_get_value" accepts default
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argument. It will be returned if no value was found or a path component is
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missing. And the fourth argument can set a variable path separator.
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#### `type3x`
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Returns a string description of the type when passed a value. Type can be a string, array, hash, float, integer, or boolean. This function will be removed when Puppet 3 support is dropped and the new type system can be used. *Type*: rvalue.

‎lib/puppet/parser/functions/try_get_value.rb‎

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module Puppet::Parser::Functions
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newfunction(
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:try_get_value,
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:type => :rvalue,
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:arity => -2,
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:doc => <<-eos
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Looks up into a complex structure of arrays and hashes and returns a value
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or the default value if nothing was found.
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Key can contain slashes to describe path components. The function will go down
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the structure and try to extract the required value.
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$data = {
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'a' => {
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'b' => [
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'b1',
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'b2',
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'b3',
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]
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}
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}
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$value = try_get_value($data, 'a/b/2', 'not_found', '/')
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=> $value = 'b3'
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a -> first hash key
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b -> second hash key
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2 -> array index starting with 0
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not_found -> (optional) will be returned if there is no value or the path did not match. Defaults to nil.
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/ -> (optional) path delimiter. Defaults to '/'.
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In addition to the required "key" argument, "try_get_value" accepts default
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argument. It will be returned if no value was found or a path component is
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missing. And the fourth argument can set a variable path separator.
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eos
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) do |args|
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path_lookup = lambda do |data, path, default|
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debug "Try_get_value: #{path.inspect} from: #{data.inspect}"
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if data.nil?
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debug "Try_get_value: no data, return default: #{default.inspect}"
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break default
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end
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unless path.is_a? Array
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debug "Try_get_value: wrong path, return default: #{default.inspect}"
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break default
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end
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unless path.any?
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debug "Try_get_value: value found, return data: #{data.inspect}"
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break data
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end
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unless data.is_a? Hash or data.is_a? Array
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debug "Try_get_value: incorrect data, return default: #{default.inspect}"
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break default
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end
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key = path.shift
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if data.is_a? Array
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begin
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key = Integer key
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rescue ArgumentError
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debug "Try_get_value: non-numeric path for an array, return default: #{default.inspect}"
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break default
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end
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end
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path_lookup.call data[key], path, default
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end
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data = args[0]
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path = args[1] || ''
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default = args[2]
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separator = args[3] || '/'
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path = path.split separator
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path_lookup.call data, path, default
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end
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end

‎spec/acceptance/try_get_value_spec.rb‎

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#! /usr/bin/env ruby -S rspec
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require 'spec_helper_acceptance'
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describe 'try_get_value function', :unless => UNSUPPORTED_PLATFORMS.include?(fact('operatingsystem')) do
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describe 'success' do
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it 'try_get_valuees a value' do
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pp = <<-EOS
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$data = {
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'a' => { 'b' => 'passing'}
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}
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$tests = try_get_value($a, 'a/b')
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notice(inline_template('tests are <%= @tests.inspect %>'))
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EOS
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apply_manifest(pp, :catch_failures => true) do |r|
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expect(r.stdout).to match(/tests are "passing"/)
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end
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end
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end
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describe 'failure' do
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it 'uses a default value' do
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pp = <<-EOS
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$data = {
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'a' => { 'b' => 'passing'}
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}
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$tests = try_get_value($a, 'c/d', 'using the default value')
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notice(inline_template('tests are <%= @tests.inspect %>'))
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EOS
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apply_manifest(pp, :expect_failures => true) do |r|
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expect(r.stdout).to match(/using the default value/)
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end
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end
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it 'raises error on incorrect number of arguments' do
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pp = <<-EOS
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$o = try_get_value()
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EOS
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apply_manifest(pp, :expect_failures => true) do |r|
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expect(r.stderr).to match(/wrong number of arguments/i)
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end
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end
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end
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end

‎spec/functions/try_get_value_spec.rb‎

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require 'spec_helper'
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describe 'try_get_value' do
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let(:data) do
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{
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'a' => {
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'g' => '2',
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'e' => [
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'f0',
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'f1',
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{
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'x' => {
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'y' => 'z'
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}
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},
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'f3',
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]
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},
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'b' => true,
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'c' => false,
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'd' => '1',
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}
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end
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context 'single values' do
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it 'should exist' do
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is_expected.not_to eq(nil)
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end
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it 'should be able to return a single value' do
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is_expected.to run.with_params('test').and_return('test')
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end
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it 'should use the default value if data is a single value and path is present' do
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is_expected.to run.with_params('test', 'path', 'default').and_return('default')
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end
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it 'should return default if there is no data' do
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is_expected.to run.with_params(nil, nil, 'default').and_return('default')
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end
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it 'should be able to use data structures as default values' do
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is_expected.to run.with_params('test', 'path', data).and_return(data)
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end
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end
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context 'structure values' do
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it 'should be able to extracts a single hash value' do
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is_expected.to run.with_params(data, 'd', 'default').and_return('1')
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end
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it 'should be able to extract a deeply nested hash value' do
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is_expected.to run.with_params(data, 'a/g', 'default').and_return('2')
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end
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it 'should return the default value if the path is not found' do
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is_expected.to run.with_params(data, 'missing', 'default').and_return('default')
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end
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it 'should return the default value if the path is too long' do
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is_expected.to run.with_params(data, 'a/g/c/d', 'default').and_return('default')
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end
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it 'should support an array index in the path' do
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is_expected.to run.with_params(data, 'a/e/1', 'default').and_return('f1')
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end
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it 'should return the default value if an array index is not a number' do
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is_expected.to run.with_params(data, 'a/b/c', 'default').and_return('default')
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end
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it 'should return the default value if and index is out of array length' do
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is_expected.to run.with_params(data, 'a/e/5', 'default').and_return('default')
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end
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it 'should be able to path though both arrays and hashes' do
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is_expected.to run.with_params(data, 'a/e/2/x/y', 'default').and_return('z')
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end
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it 'should be able to return "true" value' do
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is_expected.to run.with_params(data, 'b', 'default').and_return(true)
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is_expected.to run.with_params(data, 'm', true).and_return(true)
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end
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it 'should be able to return "false" value' do
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is_expected.to run.with_params(data, 'c', 'default').and_return(false)
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is_expected.to run.with_params(data, 'm', false).and_return(false)
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end
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it 'should return "nil" if value is not found and no default value is provided' do
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is_expected.to run.with_params(data, 'a/1').and_return(nil)
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end
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it 'should be able to use a custom path separator' do
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is_expected.to run.with_params(data, 'a::g', 'default', '::').and_return('2')
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is_expected.to run.with_params(data, 'a::c', 'default', '::').and_return('default')
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end
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end
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end

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