DSL: add depends_on stanza

lib/cask.rb

@@ -16,6 +16,7 @@ class Cask; end
 require 'cask/cli'
 require 'cask/caveats'
 require 'cask/container'
+require 'cask/depends_on'
 require 'cask/download'
 require 'cask/download_strategy'
 require 'cask/dsl'

lib/cask/depends_on.rb

@@ -0,0 +1,31 @@
+class Cask::DependsOn
+
+  VALID_KEYS = Set.new [
+                        :formula,
+                        :cask,
+                        :macos,
+                        :arch,
+                        :x11,
+                        :java,
+                       ]
+
+  attr_accessor *VALID_KEYS
+  attr_accessor :pairs
+
+  def initialize(pairs={})
+    @pairs = pairs
+    pairs.each do |key, value|
+      raise "invalid depends_on key: '#{key.inspect}'" unless VALID_KEYS.include?(key)
+      writer_method = "#{key}=".to_sym
+      send(writer_method, value)
+    end
+  end
+
+  def to_yaml
+    @pairs.to_yaml
+  end
+
+  def to_s
+    @pairs.inspect
+  end
+end

lib/cask/dsl.rb

@@ -16,6 +16,8 @@ def version; self.class.version; end
 
   def depends_on_formula; self.class.depends_on_formula; end
 
+  def depends_on; self.class.depends_on; end
+
   def container_type; self.class.container_type; end
 
   def sums; self.class.sums || []; end
@@ -68,6 +70,23 @@ def depends_on_formula(*args)
       @depends_on_formula ||= args
     end
 
+    def depends_on(*args)
+      if @depends_on and !args.empty?
+        # todo: remove this constraint, and instead merge multiple depends_on stanzas
+        raise CaskInvalidError.new(self.title, "'depends_on' stanza may only appear once")
+      end
+      @depends_on ||= begin
+        Cask::DependsOn.new(*args) unless args.empty?
+      rescue StandardError => e
+        raise CaskInvalidError.new(self.title, e)
+      end
+      # todo: remove this backwards compatibility section after removing depends_on_formula
+      if @depends_on.formula
+        @depends_on_formula ||= @depends_on.formula
+      end
+      @depends_on
+    end
+
     def artifacts
       @artifacts ||= Hash.new { |hash, key| hash[key] = Set.new }
     end

test/cask/dsl_test.rb

@@ -112,4 +112,17 @@ def caveats; <<-EOS.undent
     }.must_raise(CaskInvalidError)
     err.message.must_include "'version' stanza may only appear once"
   end
+
+  describe "depends_on stanza" do
+    it "allows depends_on stanza to be specified" do
+      cask = Cask.load('with-depends-on')
+      cask.depends_on.formula.wont_be_nil
+    end
+
+    it "refuses to load invalid depends_on key" do
+      err = lambda {
+        invalid_cask = Cask.load('invalid/invalid-depends-on-key')
+      }.must_raise(CaskInvalidError)
+    end
+  end
 end

test/support/Casks/invalid/invalid-depends-on-key.rb

@@ -0,0 +1,8 @@
+class InvalidDependsOnKey < TestCask
+  url TestHelper.local_binary('caffeine.zip')
+  homepage 'http://example.com/invalid-depends-on-key'
+  depends_on :no_such_key => 'unar'
+  sha256 '9203c30951f9aab41ac294bbeb1dcef7bed401ff0b353dcb34d68af32ea51853'
+  version '1.2.3'
+  link 'Caffeine.app'
+end

test/support/Casks/with-depends-on.rb

@@ -0,0 +1,8 @@
+class WithDependsOn < TestCask
+  url TestHelper.local_binary('caffeine.zip')
+  homepage 'http://example.com/with-depends-on'
+  depends_on :formula => 'unar'
+  sha256 '9203c30951f9aab41ac294bbeb1dcef7bed401ff0b353dcb34d68af32ea51853'
+  version '1.2.3'
+  link 'Caffeine.app'
+end