Show friendly msg on config.rb Ruby syntax error (#49)

* Show friendly msg on config.rb Ruby syntax error

* More flexible assertion

The exact format of the syntax error message is different for various
versions of Ruby. Match on a substring of the error instead.

lib/tomo/cli.rb

@@ -42,7 +42,7 @@ def call(argv)
       command.parse(argv)
     rescue Interrupt
       handle_error(InterruptedError.new, command_name)
-    rescue StandardError => e
+    rescue StandardError, SyntaxError => e
       handle_error(e, command_name)
     end
 

lib/tomo/configuration.rb

@@ -23,7 +23,7 @@ def self.from_config_rb(path=DEFAULT_CONFIG_PATH)
         config.working_dir = File.dirname(path)
         DSL::ConfigFile.new(config).instance_eval(config_rb, path.to_s, 1)
       end
-    rescue StandardError => e
+    rescue StandardError, SyntaxError => e
       raise DSL::ErrorFormatter.decorate(e, path, config_rb&.lines)
     end
 

lib/tomo/configuration/dsl/error_formatter.rb

@@ -2,20 +2,31 @@ module Tomo
   class Configuration
     module DSL
       module ErrorFormatter
-        def self.decorate(error, path, lines)
-          if error.backtrace[0..1].grep(/^#{Regexp.quote(path)}:/).empty?
-            return error
+        class << self
+          def decorate(error, path, lines)
+            line_no = find_line_no(path, error.message, *error.backtrace[0..1])
+            return error if line_no.nil?
+
+            error.extend(self)
+            error.dsl_lines = lines || []
+            error.dsl_path = path
+            error.error_line_no = line_no
+            error
           end
 
-          error.extend(self)
-          error.dsl_lines = lines || []
-          error.dsl_path = path
-          error
+          private
+
+          def find_line_no(path, *lines)
+            lines.find do |line|
+              line_no = line[/^#{Regexp.quote(path)}:(\d+):/, 1]
+              break line_no.to_i if line_no
+            end
+          end
         end
 
         include Colors
 
-        attr_accessor :dsl_lines, :dsl_path
+        attr_accessor :dsl_lines, :dsl_path, :error_line_no
 
         def to_console
           <<~ERROR
@@ -39,16 +50,6 @@ def trace_hint
           HINT
         end
 
-        def error_line_no
-          @_error_line_no ||= begin
-            pattern = /^#{Regexp.quote(dsl_path)}:(\d+):/
-            backtrace.each do |entry|
-              match = pattern.match(entry)
-              break match[1].to_i if match
-            end
-          end
-        end
-
         # rubocop:disable Metrics/AbcSize
         # rubocop:disable Metrics/MethodLength
         def highlighted_lines

lib/tomo/testing/cli_tester.rb

@@ -10,8 +10,12 @@ def initialize
         @token = SecureRandom.hex(8)
       end
 
+      def in_temp_dir(&block)
+        super(token, &block)
+      end
+
       def run(*args, raise_on_error: true)
-        in_temp_dir(token) do
+        in_temp_dir do
           restoring_defaults do
             capturing_logger_output do
               handling_exit(raise_on_error) do

test/tomo/cli_test.rb

@@ -10,4 +10,55 @@ def test_execute_task_with_implicit_run_command
     @tester.run "bundler:install", "--dry-run"
     assert_match "Simulated bundler:install", @tester.stdout
   end
+
+  def test_prints_error_when_config_has_syntax_error
+    @tester.in_temp_dir do
+      FileUtils.mkdir_p(".tomo")
+      IO.write(".tomo/config.rb", <<~CONFIG)
+        plugin "git"
+        deploy do
+          run "git:clone
+          run "git:create_release"
+        end
+      CONFIG
+    end
+    @tester.run "deploy", raise_on_error: false
+    assert_match(<<~'OUTPUT'.strip, @tester.stderr.gsub(/^  /, ""))
+      ERROR: Configuration syntax error in .tomo/config.rb at line 4.
+
+        3:   run "git:clone
+      → 4:   run "git:create_release"
+        5: end
+
+      SyntaxError: .tomo/config.rb:4: syntax error
+    OUTPUT
+  end
+
+  def test_prints_error_when_config_dsl_is_used_incorrectly
+    @tester.in_temp_dir do
+      FileUtils.mkdir_p(".tomo")
+      IO.write(".tomo/config.rb", <<~CONFIG)
+        plugin "git"
+        deploy do
+          run
+          run "git:create_release"
+        end
+      CONFIG
+    end
+    @tester.run "deploy", raise_on_error: false
+    assert_equal(<<~'OUTPUT', @tester.stderr.gsub(/^  /, ""))
+
+      ERROR: Configuration syntax error in .tomo/config.rb at line 3.
+
+        2: deploy do
+      → 3:   run
+        4:   run "git:create_release"
+
+      ArgumentError: wrong number of arguments (given 0, expected 1)
+
+      Visit https://tomo-deploy.com/configuration for syntax reference.
+      You can run this command again with --trace for a full backtrace.
+
+    OUTPUT
+  end
 end