Implement recipe error reporting feature

features/recipe.feature

@@ -9,6 +9,21 @@ Feature: recipe evaluation
     Then the exit status must be 0
     And the output must contain "hello from recipe"
 
+  Scenario: reports errors when evaluating an invalid recipe
+    Given a recipe with:
+      """
+      puts 'OK'
+
+      invalid_keyword
+      """
+    When I execute the recipe
+    Then the exit status must be 70
+    And the output must match:
+      """
+      \AOK
+      recipe.rb:3:.+invalid recipe keyword `invalid_keyword'
+      """
+
   Scenario: source keyword, requires a recipe file
     Given a recipe with:
       """

lib/producer/core/cli.rb

@@ -12,17 +12,24 @@ module Producer
 
       def run!
         check_arguments!
-        evaluate_recipe_file(@arguments[1])
+        evaluate_recipe_file
       end
 
       def check_arguments!
         print_usage_and_exit(64) unless @arguments.length == 2
       end
 
-      def evaluate_recipe_file(filepath)
+      def evaluate_recipe_file
         recipe = Recipe.from_file(@arguments[1])
         env = Env.new(recipe)
-        recipe.evaluate env
+        begin
+          recipe.evaluate env
+        rescue Recipe::RecipeEvaluationError => e
+          @stdout.puts [e.backtrace.shift, e.message].join ': '
+          @stdout.puts e.backtrace
+
+          exit 70
+        end
       end
 
 

lib/producer/core/recipe.rb

@@ -1,6 +1,8 @@
 module Producer
   module Core
     class Recipe
+      RecipeEvaluationError = Class.new(StandardError)
+
       attr_reader :code, :filepath
 
       def self.from_file(filepath)
@@ -29,11 +31,15 @@ module Producer
 
         def evaluate(env)
           if @code
-            instance_eval @code
+            instance_eval @code, env.current_recipe.filepath
           else
             instance_eval &@block
           end
           self
+        rescue NameError => e
+          err = RecipeEvaluationError.new("invalid recipe keyword `#{e.name}'")
+          err.set_backtrace e.backtrace.reject { |l| l =~ /\/producer-core\// }
+          raise err
         end
 
 

spec/fixtures/recipes/invalid.rb

@@ -0,0 +1,4 @@
+# this recipe will raise a NameError on line 4 when evaluated by the recipe
+# DSL.
+
+invalid_keyword

spec/producer/core/cli_spec.rb

@@ -20,7 +20,7 @@ module Producer::Core
       end
 
       it 'evaluates the recipe' do
-        expect(cli).to receive(:evaluate_recipe_file).with(arguments[1])
+        expect(cli).to receive(:evaluate_recipe_file)
         cli.run!
       end
     end
@@ -50,14 +50,14 @@ module Producer::Core
     describe '#evaluate_recipe_file' do
       it 'builds a recipe' do
         expect(Recipe).to receive(:from_file).with(arguments[1]).and_call_original
-        cli.evaluate_recipe_file(arguments[1])
+        cli.evaluate_recipe_file
       end
 
       it 'builds an environment with the current recipe' do
         recipe = double('recipe').as_null_object
         allow(Recipe).to receive(:from_file).and_return(recipe)
         expect(Env).to receive(:new).with(recipe).and_call_original
-        cli.evaluate_recipe_file(arguments[1])
+        cli.evaluate_recipe_file
       end
 
       it 'evaluates the recipe with the environment' do
@@ -66,7 +66,33 @@ module Producer::Core
         env = double('env')
         allow(Env).to receive(:new).and_return(env)
         expect(recipe).to receive(:evaluate).with(env)
-        cli.evaluate_recipe_file(arguments[1])
+        cli.evaluate_recipe_file
+      end
+
+      context 'error during recipe evaluation' do
+        let(:arguments) { ['host', fixture_path_for('recipes/invalid.rb')] }
+        let(:stdout)    { StringIO.new }
+        subject(:cli)   { CLI.new(arguments, stdout) }
+
+        it 'exits with a return status of 70' do
+          expect { cli.evaluate_recipe_file }
+            .to raise_error(SystemExit) { |e|
+              expect(e.status).to eq 70
+            }
+        end
+
+        it 'prints the error' do
+          begin
+            cli.evaluate_recipe_file
+          rescue SystemExit
+          end
+          expect(stdout.string).to match(/
+            \A
+            #{arguments[1]}:4:
+            .+
+            invalid\srecipe\skeyword\s`invalid_keyword'
+          /x)
+        end
       end
     end
   end

spec/producer/core/recipe_spec.rb

@@ -5,7 +5,7 @@ module Producer::Core
     include FixturesHelpers
 
     let(:code)        { 'nil' }
-    let(:env)         { double('env') }
+    let(:env)         { double('env').as_null_object }
     subject(:recipe)  { Recipe.new(code) }
 
     describe '.from_file' do
@@ -88,6 +88,24 @@ module Producer::Core
         it 'returns itself' do
           expect(dsl.evaluate(env)).to eq dsl
         end
+
+        context 'invalid recipe' do
+          let(:filepath)  { fixture_path_for 'recipes/error.rb' }
+          let(:recipe)    { Recipe.from_file(filepath) }
+          subject(:dsl)   { Recipe::DSL.new File.read(filepath) }
+
+          it 'reports the recipe file path in the error' do
+            allow(env).to receive(:current_recipe) { recipe }
+            expect { dsl.evaluate(env) }.to raise_error(RuntimeError) { |e|
+              expect(e.backtrace.first).to match /\A#{filepath}/
+            }
+          end
+
+          it 'raises a RecipeEvaluationError on NameError' do
+            dsl = Recipe::DSL.new { incorrect_keyword }
+            expect { dsl.evaluate(env) }.to raise_error(Recipe::RecipeEvaluationError)
+          end
+        end
       end
 
       context 'DSL specific methods' do