Refactor Dependency.expand

2 files changed, 85 insertions, 18 deletions

diff --git a/Library/Homebrew/dependency.rb b/Library/Homebrew/dependency.rb
index 6c78e10ac..d87d74ccf 100644
--- a/Library/Homebrew/dependency.rb
+++ b/Library/Homebrew/dependency.rb
@@ -54,29 +54,35 @@ class Dependency
     tags << 'universal' if to_formula.build.has_option? 'universal'
   end
 
-  # Expand the dependencies of dependent recursively, optionally yielding
-  # [dependent, dep] pairs to allow callers to apply arbitrary filters to
-  # the list.
-  # The default filter, which is applied when a block is not given, omits
-  # optionals and recommendeds based on what the dependent has asked for.
-  def self.expand(dependent, &block)
-    dependent.deps.map do |dep|
-      prune = catch(:prune) do
+  class << self
+    # Expand the dependencies of dependent recursively, optionally yielding
+    # [dependent, dep] pairs to allow callers to apply arbitrary filters to
+    # the list.
+    # The default filter, which is applied when a block is not given, omits
+    # optionals and recommendeds based on what the dependent has asked for.
+    def expand(dependent, &block)
+      dependent.deps.map do |dep|
+        if prune?(dependent, dep, &block)
+          next
+        else
+          expand(dep.to_formula, &block) << dep
+        end
+      end.flatten.compact.uniq
+    end
+
+    def prune?(dependent, dep, &block)
+      catch(:prune) do
         if block_given?
           yield dependent, dep
         elsif dep.optional? || dep.recommended?
-          Dependency.prune unless dependent.build.with?(dep.name)
+          prune unless dependent.build.with?(dep.name)
         end
       end
+    end
 
-      next if prune
-
-      expand(dep.to_formula, &block) << dep
-    end.flatten.compact.uniq
-  end
-
-  # Used to prune dependencies when calling expand with a block.
-  def self.prune
-    throw(:prune, true)
+    # Used to prune dependencies when calling expand with a block.
+    def prune
+      throw(:prune, true)
+    end
   end
 end
diff --git a/Library/Homebrew/test/test_dependency_expansion.rb b/Library/Homebrew/test/test_dependency_expansion.rb
new file mode 100644
index 000000000..02a05dd1a
--- /dev/null
+++ b/Library/Homebrew/test/test_dependency_expansion.rb
@@ -0,0 +1,61 @@
+require 'testing_env'
+require 'dependency'
+
+class DependencyExpansionTests < Test::Unit::TestCase
+  def build_dep(name, deps=[])
+    dep = Dependency.new(name)
+    dep.stubs(:to_formula).returns(stub(:deps => deps))
+    dep
+  end
+
+  def setup
+    @foo = build_dep(:foo)
+    @bar = build_dep(:bar)
+    @baz = build_dep(:baz)
+    @qux = build_dep(:qux)
+    @deps = [@foo, @bar, @baz, @qux]
+    @f    = stub(:deps => @deps)
+  end
+
+  def test_expand_yields_dependent_and_dep_pairs
+    i = 0
+    Dependency.expand(@f) do |dependent, dep|
+      assert_equal @f, dependent
+      assert_equal dep, @deps[i]
+      i += 1
+    end
+  end
+
+  def test_expand_no_block
+    assert_equal @deps, Dependency.expand(@f)
+  end
+
+  def test_expand_prune_all
+    assert_empty Dependency.expand(@f) { Dependency.prune }
+  end
+
+  def test_expand_selective_pruning
+    deps = Dependency.expand(@f) do |_, dep|
+      Dependency.prune if dep.name == :foo
+    end
+
+    assert_equal [@bar, @baz, @qux], deps
+  end
+
+  def test_expand_preserves_dependency_order
+    @foo.stubs(:to_formula).returns(stub(:deps => [@qux, @baz]))
+    assert_equal [@qux, @baz, @foo, @bar], Dependency.expand(@f)
+  end
+
+  def test_expand_skips_optionals_by_default
+    @foo.expects(:optional?).returns(true)
+    @f = stub(:deps => @deps, :build => stub(:with? => false))
+    assert_equal [@bar, @baz, @qux], Dependency.expand(@f)
+  end
+
+  def test_expand_keeps_recommendeds_by_default
+    @foo.expects(:recommended?).returns(true)
+    @f = stub(:deps => @deps, :build => stub(:with? => true))
+    assert_equal @deps, Dependency.expand(@f)
+  end
+end