Use a priority queue to select compilers

The existing case-statement with nested if-statements is gross and hard
to extend. Replacing it with a priority queue simplifies the logic and
makes it very easy to add new compilers to the fails_with system, which
we will likely want to do in the future.

1 files changed, 38 insertions, 0 deletions

diff --git a/Library/Homebrew/test/test_compiler_queue.rb b/Library/Homebrew/test/test_compiler_queue.rb
new file mode 100644
index 000000000..6dee1ab37
--- /dev/null
+++ b/Library/Homebrew/test/test_compiler_queue.rb
@@ -0,0 +1,38 @@
+require 'testing_env'
+require 'compilers'
+
+class CompilerQueueTests < Test::Unit::TestCase
+  FakeCompiler = Struct.new(:name, :priority)
+
+  def setup
+    @q = CompilerQueue.new
+  end
+
+  def test_shovel_returns_self
+    assert_same @q, (@q << Object.new)
+  end
+
+  def test_empty
+    assert @q.empty?
+  end
+
+  def test_queues_items
+    a = FakeCompiler.new(:foo, 0)
+    b = FakeCompiler.new(:bar, 0)
+    @q << a << b
+    assert_equal a, @q.pop
+    assert_equal b, @q.pop
+    assert_nil @q.pop
+  end
+
+  def test_pops_items_by_priority
+    a = FakeCompiler.new(:foo, 0)
+    b = FakeCompiler.new(:bar, 0.5)
+    c = FakeCompiler.new(:baz, 1)
+    @q << a << b << c
+    assert_equal c, @q.pop
+    assert_equal b, @q.pop
+    assert_equal a, @q.pop
+    assert_nil @q.pop
+  end
+end