Refactor dig44 function

The current implementation of the dig44 function has the
following problems:
* Doesn't recognise Puppet4's :undef value as an empty value
  and doesn't return the default value.
* Doesn't make a different between false and nil value
  and returns the default value for a non-empty false value

2 files changed, 119 insertions, 41 deletions

diff --git a/lib/puppet/parser/functions/dig44.rb b/lib/puppet/parser/functions/dig44.rb
index a7de363..d703380 100644
--- a/lib/puppet/parser/functions/dig44.rb
+++ b/lib/puppet/parser/functions/dig44.rb
@@ -1,23 +1,30 @@
-#
-# dig44.rb
+#		
+# dig44.rb		
 #
 
 module Puppet::Parser::Functions
-  newfunction(:dig44, :type => :rvalue, :doc => <<-EOS
+  newfunction(
+      :dig44,
+      :type => :rvalue,
+      :arity => -2,
+      :doc => <<-eos
 DEPRECATED: This function has been replaced in puppet 4.5.0.
 
-Looks up into a complex structure of arrays and hashes and returns nil
+Looks up into a complex structure of arrays and hashes and returns a value
 or the default value if nothing was found.
 
-Path is an array of keys to be looked up in data argument. The function
-will go down the structure and try to extract the required value.
+Key can contain slashes to describe path components. The function will go down
+the structure and try to extract the required value.
 
 $data = {
   'a' => {
     'b' => [
       'b1',
       'b2',
-      'b3' ]}}
+      'b3',
+    ]
+  }
+}
 
 $value = dig44($data, ['a', 'b', '2'], 'not_found')
 => $value = 'b3'
@@ -29,18 +36,18 @@ b -> second hash key
 not_found -> (optional) will be returned if there is no value or the path
 did not match. Defaults to nil.
 
-In addition to the required "path" argument, "dig44" accepts default
+In addition to the required "key" argument, the function accepts a default
 argument. It will be returned if no value was found or a path component is
 missing. And the fourth argument can set a variable path separator.
-    EOS
-             ) do |arguments|
+  eos
+  ) do |arguments|
     # Two arguments are required
     raise(Puppet::ParseError, "dig44(): Wrong number of arguments " +
                               "given (#{arguments.size} for at least 2)") if arguments.size < 2
 
     data, path, default = *arguments
 
-    if !(data.is_a?(Hash) || data.is_a?(Array))
+    unless data.is_a?(Hash) or data.is_a?(Array)
       raise(Puppet::ParseError, "dig44(): first argument must be a hash or an array, " <<
                                 "given #{data.class.name}")
     end
@@ -50,7 +57,17 @@ missing. And the fourth argument can set a variable path separator.
                                 "given #{path.class.name}")
     end
 
-    value = path.reduce(data) { |h, k| (h.is_a?(Hash) || h.is_a?(Array)) ? h[k] : break }
+    value = path.reduce(data) do |structure, key|
+      if structure.is_a? Hash or structure.is_a? Array
+        if structure.is_a? Array
+          key = Integer key rescue break
+        end
+        break if structure[key].nil? or structure[key] == :undef
+        structure[key]
+      else
+        break
+      end
+    end
     value.nil? ? default : value
   end
 end
diff --git a/spec/functions/dig44_spec.rb b/spec/functions/dig44_spec.rb
index fd451ff..4f7408d 100644
--- a/spec/functions/dig44_spec.rb
+++ b/spec/functions/dig44_spec.rb
@@ -1,44 +1,105 @@
 require 'spec_helper'
 
 describe 'dig44' do
-  it "should exist" do
-    expect(Puppet::Parser::Functions.function("dig44")).to eq("function_dig44")
+
+  let(:data) do
+    {
+        'a' => {
+            'g' => '2',
+            'e' => [
+                'f0',
+                'f1',
+                {
+                    'x' => {
+                        'y' => 'z'
+                    }
+                },
+                'f3',
+            ]
+        },
+        'b' => true,
+        'c' => false,
+        'd' => '1',
+        'e' => :undef,
+        'f' => nil,
+    }
   end
 
-  it "should raise a ParseError if there are less than 2 arguments" do
-    expect { scope.function_dig44([]) }.to raise_error(Puppet::ParseError)
-  end 
+  context 'single values' do
+    it 'should exist' do
+      is_expected.not_to be_nil
+    end
 
-  it "should raise a ParseError if the first argument isn't a hash or array" do
-    expect { scope.function_dig44(['bad', []]) }.to raise_error(Puppet::ParseError)
-  end 
+    it 'should require two arguments' do
+      is_expected.to run.with_params().and_raise_error(ArgumentError)
+    end
 
-  it "should raise a ParseError if the second argument isn't an array" do
-    expect { scope.function_dig44([{}, 'bad']) }.to raise_error(Puppet::ParseError)
-  end
+    it 'should fail if the data is not a structure' do
+      is_expected.to run.with_params('test', []).and_raise_error(Puppet::Error)
+    end
 
-  it "should return an empty hash when given empty parameters" do
-    result = scope.function_dig44([{}, []])
-    expect(result).to(eq({}))
-  end
+    it 'should fail if the path is not an array' do
+      is_expected.to run.with_params({}, '').and_raise_error(Puppet::Error)
+    end
 
-  it "should return value when given simple hash" do
-    result = scope.function_dig44([{"a" => "b"}, ["a"]])
-    expect(result).to(eq("b"))
-  end
+    it 'should return the value if the value is string' do
+      is_expected.to run.with_params(data, ['d'], 'default').and_return('1')
+    end
 
-  it "should find hash values two levels deep" do
-    result = scope.function_dig44([{"a" => {"b" => "c"}}, ["a", "b"]])
-    expect(result).to(eq("c"))
-  end
+    it 'should return true if the value is true' do
+      is_expected.to run.with_params(data, ['b'], 'default').and_return(true)
+    end
 
-  it "should return default value if nothing was found" do
-    result = scope.function_dig44([{}, ["a", "b"], "d"])
-    expect(result).to(eq("d"))
+    it 'should return false if the value is false' do
+      is_expected.to run.with_params(data, ['c'], 'default').and_return(false)
+    end
+
+    it 'should return the default if the value is nil' do
+      is_expected.to run.with_params(data, ['f'], 'default').and_return('default')
+    end
+
+    it 'should return the default if the value is :undef (same as nil)' do
+      is_expected.to run.with_params(data, ['e'], 'default').and_return('default')
+    end
+
+    it 'should return the default if the path is not found' do
+      is_expected.to run.with_params(data, ['missing'], 'default').and_return('default')
+    end
   end
 
-  it "should work on booleans as well as strings" do
-    result = scope.function_dig44([{"a" => false}, ["a"]])
-    expect(result).to(eq(false))
+  context 'structure values' do
+
+    it 'should be able to extract a deeply nested hash value' do
+      is_expected.to run.with_params(data, %w(a g), 'default').and_return('2')
+    end
+
+    it 'should return the default value if the path is too long' do
+      is_expected.to run.with_params(data, %w(a g c d), 'default').and_return('default')
+    end
+
+    it 'should support an array index (number) in the path' do
+      is_expected.to run.with_params(data, ['a', 'e', 1], 'default').and_return('f1')
+    end
+
+    it 'should support an array index (string) in the path' do
+      is_expected.to run.with_params(data, %w(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, %w(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, %w(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, %w(a e 2 x y), 'default').and_return('z')
+    end
+
+    it 'should return "nil" if value is not found and no default value is provided' do
+      is_expected.to run.with_params(data, %w(a 1)).and_return(nil)
+    end
+
   end
 end