Add Node#string_literal? to match str and dstr and `Node#string…

…_type?` to match `str`, `dstr` and `xstr` types.

changelog/new_add_nodestring_literal_to_match_str_and.md

@@ -0,0 +1 @@
+* [#328](https://github.com/rubocop/rubocop-ast/pull/328): Add `Node#string_literal?` to match `str` and `dstr` and `Node#string_type?` to match `str`, `dstr` and `xstr` types. ([@dvandersluis][])

lib/rubocop/ast/node.rb

@@ -41,6 +41,8 @@ class Node < Parser::AST::Node # rubocop:disable Metrics/ClassLength
       # @api private
       BASIC_LITERALS = (LITERALS - COMPOSITE_LITERALS).freeze
       # @api private
+      STRING_LITERALS = %i[str dstr].freeze
+      # @api private
       MUTABLE_LITERALS = %i[str dstr xstr array hash
                             regexp irange erange].to_set.freeze
       # @api private
@@ -385,6 +387,10 @@ def basic_literal?
         BASIC_LITERALS.include?(type)
       end
 
+      def string_literal?
+        STRING_LITERALS.include?(type)
+      end
+
       def truthy_literal?
         TRUTHY_LITERALS.include?(type)
       end
@@ -483,6 +489,10 @@ def boolean_type?
         true_type? || false_type?
       end
 
+      def string_type?
+        str_type? || dstr_type? || xstr_type?
+      end
+
       def numeric_type?
         int_type? || float_type? || rational_type? || complex_type?
       end

spec/rubocop/ast/node_spec.rb

@@ -855,6 +855,74 @@ class << expr
     end
   end
 
+  describe '#string_literal?' do
+    context 'when string literal' do
+      let(:src) { %q{'foo'} }
+
+      it 'is true' do
+        expect(node).to be_string_literal
+      end
+    end
+
+    context 'when interpolated string' do
+      let(:src) { %q{"foo #{bar}"} }
+
+      it 'is true' do
+        expect(node).to be_string_literal
+      end
+    end
+
+    context 'when `xstr` node' do
+      let(:src) { '`ls`' }
+
+      it 'is true' do
+        expect(node).not_to be_string_literal
+      end
+    end
+
+    context 'when numeric literal' do
+      let(:src) { '42' }
+
+      it 'is false' do
+        expect(node).not_to be_string_literal
+      end
+    end
+  end
+
+  describe '#string_type?' do
+    context 'when string literal' do
+      let(:src) { %q{'foo'} }
+
+      it 'is true' do
+        expect(node).to be_string_type
+      end
+    end
+
+    context 'when interpolated string' do
+      let(:src) { %q{"foo #{bar}"} }
+
+      it 'is true' do
+        expect(node).to be_string_type
+      end
+    end
+
+    context 'when `xstr` node' do
+      let(:src) { '`ls`' }
+
+      it 'is true' do
+        expect(node).to be_string_type
+      end
+    end
+
+    context 'when numeric literal' do
+      let(:src) { '42' }
+
+      it 'is false' do
+        expect(node).not_to be_string_type
+      end
+    end
+  end
+
   describe '#numeric_type?' do
     context 'when integer literal' do
       let(:src) { '42' }
@@ -899,7 +967,7 @@ class << expr
     context 'when string literal' do
       let(:src) { '"42"' }
 
-      it 'is true' do
+      it 'is false' do
         expect(node).not_to be_numeric_type
       end
     end