Merge afa2fb4 into 6649685

lib/guard/plugin_util.rb

@@ -74,7 +74,11 @@ def initialize_plugin(options)
       if klass.superclass.to_s == "Guard::Guard"
         klass.new(options.delete(:watchers), options)
       else
-        klass.new(options)
+        begin
+          klass.new(options)
+        rescue ArgumentError => e
+          fail "Failed to call #{klass}.new(options): #{e}"
+        end
       end
     end
 

lib/guard/reevaluator.rb

@@ -7,6 +7,9 @@ def run_on_modifications(files)
       return unless ::Guard::Watcher.match_guardfile?(files)
       ::Guard.save_scope
       ::Guard.evaluator.reevaluate_guardfile
+    rescue ScriptError, StandardError => e
+      ::Guard::UI.warning("Failed to reevaluate file: #{e}")
+    ensure
       ::Guard.restore_scope
     end
   end

spec/lib/guard/reevaluator_spec.rb

@@ -2,6 +2,7 @@
 require "guard/plugin"
 
 require "guard/reevaluator.rb"
+require "guard/ui"
 
 describe Guard::Reevaluator do
   let(:options) { {} }
@@ -27,9 +28,48 @@
       expect(evaluator).to receive(:reevaluate_guardfile)
       subject.run_on_modifications(["Guardfile"])
     end
+
+    context "when Guardfile contains errors" do
+      let(:failure) { proc { fail RuntimeError, "Could not load Foo!" } }
+
+      before do
+        allow(evaluator).to receive(:reevaluate_guardfile) { failure.call }
+      end
+
+      context "with a name error" do
+        let(:failure) { proc { fail NameError, "Could not load Foo!" } }
+        it "should not raise error to prevent being fired" do
+          expect { subject.run_on_modifications(["Guardfile"]) }.
+            to_not raise_error
+        end
+      end
+
+      context "with a syntax error" do
+        let(:failure) { proc { fail SyntaxError, "Could not load Foo!" } }
+        it "should not raise error to prevent being fired" do
+          expect { subject.run_on_modifications(["Guardfile"]) }.
+            to_not raise_error
+        end
+      end
+
+      # TODO: show backtrace?
+      it "should show warning about the error" do
+        expect(::Guard::UI).to receive(:warning).
+          with("Failed to reevaluate file: Could not load Foo!")
+
+        subject.run_on_modifications(["Guardfile"])
+      end
+
+      it "should restore the scope" do
+        expect(::Guard).to receive(:restore_scope)
+
+        subject.run_on_modifications(["Guardfile"])
+      end
+    end
+
   end
 
-  context "when Guardfile is modified" do
+  context "when Guardfile is not modified" do
     before do
       allow(::Guard::Watcher).to receive(:match_guardfile?).with(["foo"]).
         and_return(false)