Add a new function "try_get_value"

* Extracts a value from a deeply-nested data structure
* Returns default if a value could not be extracted

2 files changed, 147 insertions, 0 deletions

diff --git a/spec/acceptance/try_get_value_spec.rb b/spec/acceptance/try_get_value_spec.rb
new file mode 100755
index 0000000..46b1c4d
--- /dev/null
+++ b/spec/acceptance/try_get_value_spec.rb
@@ -0,0 +1,47 @@
+#! /usr/bin/env ruby -S rspec
+require 'spec_helper_acceptance'
+
+describe 'try_get_value function', :unless => UNSUPPORTED_PLATFORMS.include?(fact('operatingsystem')) do
+  describe 'success' do
+    it 'try_get_valuees a value' do
+      pp = <<-EOS
+      $data = {
+        'a' => { 'b' => 'passing'}
+      }
+
+      $tests = try_get_value($a, 'a/b')
+      notice(inline_template('tests are <%= @tests.inspect %>'))
+      EOS
+
+      apply_manifest(pp, :catch_failures => true) do |r|
+        expect(r.stdout).to match(/tests are "passing"/)
+      end
+    end
+  end
+  describe 'failure' do
+    it 'uses a default value' do
+      pp = <<-EOS
+      $data = {
+        'a' => { 'b' => 'passing'}
+      }
+
+      $tests = try_get_value($a, 'c/d', 'using the default value')
+      notice(inline_template('tests are <%= @tests.inspect %>'))
+      EOS
+
+      apply_manifest(pp, :expect_failures => true) do |r|
+        expect(r.stdout).to match(/using the default value/)
+      end
+    end
+
+    it 'raises error on incorrect number of arguments' do
+      pp = <<-EOS
+      $o = try_get_value()
+      EOS
+
+      apply_manifest(pp, :expect_failures => true) do |r|
+        expect(r.stderr).to match(/wrong number of arguments/i)
+      end
+    end
+  end
+end
diff --git a/spec/functions/try_get_value_spec.rb b/spec/functions/try_get_value_spec.rb
new file mode 100644
index 0000000..38c0efd
--- /dev/null
+++ b/spec/functions/try_get_value_spec.rb
@@ -0,0 +1,100 @@
+require 'spec_helper'
+
+describe 'try_get_value' do
+
+  let(:data) do
+    {
+        'a' => {
+            'g' => '2',
+            'e' => [
+                'f0',
+                'f1',
+                {
+                    'x' => {
+                        'y' => 'z'
+                    }
+                },
+                'f3',
+            ]
+        },
+        'b' => true,
+        'c' => false,
+        'd' => '1',
+    }
+  end
+
+  context 'single values' do
+    it 'should exist' do
+      is_expected.not_to eq(nil)
+    end
+
+    it 'should be able to return a single value' do
+      is_expected.to run.with_params('test').and_return('test')
+    end
+
+    it 'should use the default value if data is a single value and path is present' do
+      is_expected.to run.with_params('test', 'path', 'default').and_return('default')
+    end
+
+    it 'should return default if there is no data' do
+      is_expected.to run.with_params(nil, nil, 'default').and_return('default')
+    end
+
+    it 'should be able to use data structures as default values' do
+      is_expected.to run.with_params('test', 'path', data).and_return(data)
+    end
+  end
+
+  context 'structure values' do
+    it 'should be able to extracts a single hash value' do
+      is_expected.to run.with_params(data, 'd', 'default').and_return('1')
+    end
+
+    it 'should be able to extract a deeply nested hash value' do
+      is_expected.to run.with_params(data, 'a/g', 'default').and_return('2')
+    end
+
+    it 'should return the default value if the path is not found' do
+      is_expected.to run.with_params(data, 'missing', 'default').and_return('default')
+    end
+
+    it 'should return the default value if the path is too long' do
+      is_expected.to run.with_params(data, 'a/g/c/d', 'default').and_return('default')
+    end
+
+    it 'should support an array index in the path' do
+      is_expected.to run.with_params(data, 'a/e/1', 'default').and_return('f1')
+    end
+
+    it 'should return the default value if an array index is not a number' do
+      is_expected.to run.with_params(data, 'a/b/c', 'default').and_return('default')
+    end
+
+    it 'should return the default value if and index is out of array length' do
+      is_expected.to run.with_params(data, 'a/e/5', 'default').and_return('default')
+    end
+
+    it 'should be able to path though both arrays and hashes' do
+      is_expected.to run.with_params(data, 'a/e/2/x/y', 'default').and_return('z')
+    end
+
+    it 'should be able to return "true" value' do
+      is_expected.to run.with_params(data, 'b', 'default').and_return(true)
+      is_expected.to run.with_params(data, 'm', true).and_return(true)
+    end
+
+    it 'should be able to return "false" value' do
+      is_expected.to run.with_params(data, 'c', 'default').and_return(false)
+      is_expected.to run.with_params(data, 'm', false).and_return(false)
+    end
+
+    it 'should return "nil" if value is not found and no default value is provided' do
+      is_expected.to run.with_params(data, 'a/1').and_return(nil)
+    end
+
+    it 'should be able to use a custom path separator' do
+      is_expected.to run.with_params(data, 'a::g', 'default', '::').and_return('2')
+      is_expected.to run.with_params(data, 'a::c', 'default', '::').and_return('default')
+    end
+  end
+end