From 02b5ee01c806e7c2a7517432b9dbea09c3573217 Mon Sep 17 00:00:00 2001
From: Tejas Bubane <tejasbubane@gmail.com>
Date: Mon, 1 Jun 2020 14:51:08 +0530
Subject: [PATCH] Add interpolation? check for RegexpNode

Closes #4
---
 CHANGELOG.md                         |  4 ++++
 lib/rubocop/ast/node/regexp_node.rb  |  5 +++++
 spec/rubocop/ast/regexp_node_spec.rb | 20 ++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7762bc3b7..7a3eb678f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### New features
+
+* [#4](https://github.com/rubocop-hq/rubocop-ast/issues/4): Add `interpolation?` for `RegexpNode`. ([@tejasbubane][])
+
 ## 0.0.3 (2020-05-15)
 
 ### Changes
diff --git a/lib/rubocop/ast/node/regexp_node.rb b/lib/rubocop/ast/node/regexp_node.rb
index 5ca476e08..dfa04c136 100644
--- a/lib/rubocop/ast/node/regexp_node.rb
+++ b/lib/rubocop/ast/node/regexp_node.rb
@@ -31,6 +31,11 @@ def regopt
       def content
         children.select(&:str_type?).map(&:str_content).join
       end
+
+      # @return [Bool] if regexp contains interpolation
+      def interpolation?
+        children.any?(&:begin_type?)
+      end
     end
   end
 end
diff --git a/spec/rubocop/ast/regexp_node_spec.rb b/spec/rubocop/ast/regexp_node_spec.rb
index 1897f5976..e2d605eb0 100644
--- a/spec/rubocop/ast/regexp_node_spec.rb
+++ b/spec/rubocop/ast/regexp_node_spec.rb
@@ -140,4 +140,24 @@
       it { expect(content).to eq("\n.+\n") }
     end
   end
+
+  describe '#interpolation?' do
+    context 'with direct variable interpoation' do
+      let(:source) { '/\n\n#{foo}(abc)+/' }
+
+      it { expect(regexp_node.interpolation?).to eq(true) }
+    end
+
+    context 'with regexp quote' do
+      let(:source) { '/\n\n#{Regexp.quote(foo)}(abc)+/' }
+
+      it { expect(regexp_node.interpolation?).to eq(true) }
+    end
+
+    context 'with no interpolation returns false' do
+      let(:source) { '/a{3,6}/' }
+
+      it { expect(regexp_node.interpolation?).to eq(false) }
+    end
+  end
 end