Add Node#loc_is? for easier test of locations

lib/rubocop/ast/node.rb

@@ -534,6 +534,17 @@ def guard_clause?
         node.match_guard_clause?
       end
 
+      # Shortcut to safely test a particular location, even if
+      # this location does not exist or is `nil`
+      def loc_is?(which_loc, str)
+        return false unless loc.respond_to?(which_loc)
+
+        location = loc.public_send(which_loc)
+        return false unless location
+
+        location.is?(str)
+      end
+
       # @!method match_guard_clause?(node = self)
       def_node_matcher :match_guard_clause?, <<~PATTERN
         [${(send nil? {:raise :fail} ...) return break next} single_line?]

spec/rubocop/ast/node_spec.rb

@@ -1109,4 +1109,28 @@ class << expr
       end
     end
   end
+
+  describe '#loc_is?' do
+    let(:src) { '%i[>> sym << sym2]' }
+
+    context 'when loc exists' do
+      let(:src) { ':sym' }
+
+      it 'returns true when loc matches argument' do
+        expect(node).to be_loc_is(:begin, ':')
+      end
+
+      it 'returns false when loc does not match argument' do
+        expect(node).not_to be_loc_is(:begin, '!')
+      end
+    end
+
+    it 'returns false when requested loc is `nil`' do
+      expect(node).not_to be_loc_is(:begin, ':')
+    end
+
+    it 'returns false when requested loc does not exist' do
+      expect(node).not_to be_loc_is(:foo, ':')
+    end
+  end
 end