(#8708) Add has_key function

It is difficult to use existance of keys in a hash
as a boolean condition in Puppet (see #8705)

This function provides a working solution until
the underlying issue in Puppet can be resolved.

Reviewed-by: Jeff McCune

2 files changed, 73 insertions, 0 deletions

diff --git a/lib/puppet/parser/functions/has_key.rb b/lib/puppet/parser/functions/has_key.rb
new file mode 100644
index 0000000..9c1c4c3
--- /dev/null
+++ b/lib/puppet/parser/functions/has_key.rb
@@ -0,0 +1,27 @@
+module Puppet::Parser::Functions
+
+  newfunction(:has_key, :type => :rvalue, :doc => <<-'ENDHEREDOC') do |args|
+    determine if a hash has a certain key value.
+
+    Example:
+      $my_hash = {'key_one' => 'value_one'}
+      if has_key($my_hash, 'key_two') {
+        notice('we will not reach here')
+      }
+      if has_key($my_hash, 'key_one') {
+        notice('this will be printed')
+      }
+
+    ENDHEREDOC
+
+    unless args.length == 2
+      raise Puppet::ParseError, ("has_key(): wrong number of arguments (#{args.length}; must be 2)")
+    end
+    unless args[0].is_a?(Hash)
+      raise Puppet::ParseError, "has_key(): expects the first argument to be a hash, got #{args[0].inspect} which is of type #{args[0].class}"
+    end
+    args[0].has_key?(args[1])
+
+  end
+
+end
diff --git a/spec/unit/puppet/parser/functions/has_key_spec.rb b/spec/unit/puppet/parser/functions/has_key_spec.rb
new file mode 100644
index 0000000..d1dcd15
--- /dev/null
+++ b/spec/unit/puppet/parser/functions/has_key_spec.rb
@@ -0,0 +1,46 @@
+require 'puppet'
+require 'mocha'
+describe Puppet::Parser::Functions.function(:has_key) do
+
+  # Pulled from Dan's create_resources function
+  # TODO - this should be moved to spec_helper since the
+  # logic is likely to be applied to multiple rspec files.
+  let(:compiler) {
+    topscope = Puppet::Parser::Scope.new
+    # This is necessary so we don't try to use the compiler to discover our parent.
+    topscope.parent = nil
+    my_scope = Puppet::Parser::Scope.new
+    my_scope.compiler = Puppet::Parser::Compiler.new(Puppet::Node.new("floppy", :environment => 'production'))
+    my_scope.parent = topscope
+    compiler = my_scope.compiler
+  }
+  let(:scope) {
+    scope = Puppet::Parser::Scope.new
+    scope.stubs(:environment).returns(Puppet::Node::Environment.new('production'))
+    scope
+  }
+
+  describe 'when calling has_key from puppet' do
+    it "should not compile when no arguments are passed" do
+      Puppet[:code] = 'has_key()'
+      expect { compiler.compile }.should raise_error(Puppet::ParseError, /wrong number of arguments/)
+    end
+    it "should not compile when 1 argument is passed" do
+      Puppet[:code] = "has_key('foo')"
+      expect { compiler.compile }.should raise_error(Puppet::ParseError, /wrong number of arguments/)
+    end
+    it "should require the first value to be a Hash" do
+      Puppet[:code] = "has_key('foo', 'bar')"
+      expect { compiler.compile }.should raise_error(Puppet::ParseError, /expects the first argument to be a hash/)
+    end
+  end
+  describe 'when calling the function has_key from a scope instance' do
+    it 'should detect existing keys' do
+      scope.function_has_key([{'one' => 1}, 'one']).should be_true
+    end
+    it 'should detect existing keys' do
+      scope.function_has_key([{'one' => 1}, 'two']).should be_false
+    end
+  end
+
+end