fix: support symbolic chain operators on ruby 2.6

lib/rubyshell/chainer.rb

@@ -28,7 +28,7 @@ def settings
     end
 
     def method_missing(method_name, *args, &block)
-      if method_name.start_with?(/[^A-Za-z0-9]/)
+      if method_name.to_s.match?(/\A[^A-Za-z0-9]/)
         handle_chain(method_name, args.first)
       else
         super

lib/rubyshell/command.rb

@@ -41,7 +41,7 @@ def parsed_args
     private
 
     def method_missing(method_name, *args, &block)
-      if method_name.start_with?(/[^A-Za-z0-9]/)
+      if method_name.to_s.match?(/\A[^A-Za-z0-9]/)
         RubyShell::Chainer.new(self).send(method_name, *args, block)
       else
         super

spec/chainer_spec.rb

@@ -10,6 +10,28 @@
   end
 
   describe "Validating Chains" do
+    context "when chaining several commands with symbolic pipe operators" do
+      def subject_call
+        sh do
+          (printf!("hello") | cat! | cat!).exec
+        end
+      end
+
+      it "executes every command in the pipeline" do
+        expect(subject_call).to eq("hello")
+      end
+    end
+
+    context "when an unknown ordinary method is called on a command" do
+      def subject_call
+        RubyShell::Command.new("printf", "hello").unknown_chain_method
+      end
+
+      it "raises for the requested method instead of operator detection" do
+        expect { subject_call }.to raise_error(NoMethodError, /unknown_chain_method/)
+      end
+    end
+
     context "when counting files in current folder" do
       def subject_call
         sh do