From 060e5b3c77d3f1958480a35e3eb57f4a041ae9be Mon Sep 17 00:00:00 2001
From: Daniel Vandersluis <daniel.vandersluis@gmail.com>
Date: Sat, 23 Jan 2021 14:25:11 -0500
Subject: [PATCH] Fix `#value` for a `dstr` node.

---
 changelog/change_fix_value_for_a_dstr_node.md |  1 +
 lib/rubocop/ast.rb                            |  1 +
 lib/rubocop/ast/builder.rb                    |  2 +-
 lib/rubocop/ast/node/dstr_node.rb             | 16 ++++++++
 spec/rubocop/ast/dstr_node_spec.rb            | 38 +++++++++++++++++++
 5 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 changelog/change_fix_value_for_a_dstr_node.md
 create mode 100644 lib/rubocop/ast/node/dstr_node.rb
 create mode 100644 spec/rubocop/ast/dstr_node_spec.rb

diff --git a/changelog/change_fix_value_for_a_dstr_node.md b/changelog/change_fix_value_for_a_dstr_node.md
new file mode 100644
index 000000000..adc818b54
--- /dev/null
+++ b/changelog/change_fix_value_for_a_dstr_node.md
@@ -0,0 +1 @@
+* [#167](https://github.com/rubocop-hq/rubocop-ast/pull/167): Fix `#value` for `dstr` nodes to return the actual string value. ([@dvandersluis][])
diff --git a/lib/rubocop/ast.rb b/lib/rubocop/ast.rb
index 416bd3342..be4be80ac 100644
--- a/lib/rubocop/ast.rb
+++ b/lib/rubocop/ast.rb
@@ -72,6 +72,7 @@
 require_relative 'ast/node/self_class_node'
 require_relative 'ast/node/send_node'
 require_relative 'ast/node/str_node'
+require_relative 'ast/node/dstr_node'
 require_relative 'ast/node/super_node'
 require_relative 'ast/node/symbol_node'
 require_relative 'ast/node/until_node'
diff --git a/lib/rubocop/ast/builder.rb b/lib/rubocop/ast/builder.rb
index e875fbd32..51409cbcc 100644
--- a/lib/rubocop/ast/builder.rb
+++ b/lib/rubocop/ast/builder.rb
@@ -42,6 +42,7 @@ class Builder < Parser::Builders::Default
         def:          DefNode,
         defined?:     DefinedNode,
         defs:         DefNode,
+        dstr:         DstrNode,
         ensure:       EnsureNode,
         for:          ForNode,
         forward_args: ForwardArgsNode,
@@ -68,7 +69,6 @@ class Builder < Parser::Builders::Default
         csend:        SendNode,
         send:         SendNode,
         str:          StrNode,
-        dstr:         StrNode,
         xstr:         StrNode,
         sclass:       SelfClassNode,
         super:        SuperNode,
diff --git a/lib/rubocop/ast/node/dstr_node.rb b/lib/rubocop/ast/node/dstr_node.rb
new file mode 100644
index 000000000..413569898
--- /dev/null
+++ b/lib/rubocop/ast/node/dstr_node.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module AST
+    # A node extension for `dstr` nodes. This will be used
+    # in place of a plain node when the builder constructs the AST, making
+    # its methods available to all `dstr` nodes within RuboCop.
+    class DstrNode < StrNode
+      def value
+        child_nodes.map do |child|
+          child.respond_to?(:value) ? child.value : child.source
+        end.join
+      end
+    end
+  end
+end
diff --git a/spec/rubocop/ast/dstr_node_spec.rb b/spec/rubocop/ast/dstr_node_spec.rb
new file mode 100644
index 000000000..156ced2bc
--- /dev/null
+++ b/spec/rubocop/ast/dstr_node_spec.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::AST::DstrNode do
+  subject(:dstr_node) { parse_source(source).ast }
+
+  describe '#value' do
+    subject { dstr_node.value }
+
+    context 'with a multiline string' do
+      let(:source) do
+        <<~RUBY
+          'this is a multiline ' \
+          'string'
+        RUBY
+      end
+
+      it { is_expected.to eq('this is a multiline string') }
+    end
+
+    context 'with interpolation' do
+      let(:source) do
+        '"foo #{bar} baz"'
+      end
+
+      it { is_expected.to eq('foo #{bar} baz') }
+    end
+
+    context 'with implicit concatenation' do
+      let(:source) do
+        <<~RUBY
+          'foo ' 'bar ' 'baz'
+        RUBY
+      end
+
+      it { is_expected.to eq('foo bar baz') }
+    end
+  end
+end