Merge pull request #4564 from reitermarkus/not-a-cask-file-error

Raise error when file does not contain a cask.

Library/Homebrew/cask/lib/hbc/cask.rb

@@ -17,7 +17,11 @@ module Hbc
       return to_enum unless block_given?
 
       Tap.flat_map(&:cask_files).each do |f|
+        begin
           yield CaskLoader::FromTapPathLoader.new(f).load
+        rescue CaskUnreadableError => e
+          opoo e.message
+        end
       end
     end
 

Library/Homebrew/cask/lib/hbc/cask_loader.rb

@@ -54,7 +54,15 @@ module Hbc
 
         @content = IO.read(path)
 
-        instance_eval(content, path)
+        begin
+          instance_eval(content, path).tap do |cask|
+            unless cask.is_a?(Cask)
+              raise CaskUnreadableError.new(token, "'#{path}' does not contain a cask.")
+            end
+          end
+        rescue NameError, ArgumentError, ScriptError => e
+          raise CaskUnreadableError.new(token, e.message)
+        end
       end
 
       private

Library/Homebrew/cask/lib/hbc/exceptions.rb

@@ -36,6 +36,12 @@ module Hbc
     end
   end
 
+  class CaskUnreadableError < CaskUnavailableError
+    def to_s
+      "Cask '#{token}' is unreadable" << (reason.empty? ? "." : ": #{reason}")
+    end
+  end
+
   class CaskAlreadyCreatedError < AbstractCaskErrorWithToken
     def to_s
       %Q(Cask '#{token}' already exists. Run #{Formatter.identifier("brew cask edit #{token}")} to edit it.)

Library/Homebrew/test/cask/cask_loader/from__path_loader_spec.rb

@@ -0,0 +1,35 @@
+describe Hbc::CaskLoader::FromPathLoader do
+  describe "#load" do
+    context "when the file does not contain a cask" do
+      let(:path) {
+        (mktmpdir/"cask.rb").tap do |path|
+          path.write <<~RUBY
+            true
+          RUBY
+        end
+      }
+
+      it "raises an error" do
+        expect {
+          described_class.new(path).load
+        }.to raise_error(Hbc::CaskUnreadableError, /does not contain a cask/)
+      end
+    end
+
+    context "when the file calls a non-existent method" do
+      let(:path) {
+        (mktmpdir/"cask.rb").tap do |path|
+          path.write <<~RUBY
+            this_method_does_not_exist
+          RUBY
+        end
+      }
+
+      it "raises an error" do
+        expect {
+          described_class.new(path).load
+        }.to raise_error(Hbc::CaskUnreadableError, /undefined local variable or method/)
+      end
+    end
+  end
+end

Library/Homebrew/test/cask/dsl_spec.rb

@@ -46,7 +46,7 @@ describe Hbc::DSL, :cask do
       let(:token) { "invalid/invalid-header-format" }
 
       it "raises an error" do
-        expect { cask }.to raise_error(SyntaxError)
+        expect { cask }.to raise_error(Hbc::CaskUnreadableError)
       end
     end