brew ln --force is now brew ln --overwrite

* Renames --force to --overwrite, freeing up brew ln --force for #13349
* Changes --dry-run to preview linking by default, rather than
  overwriting. An overwrite dry-run can be simulated via both
  --dry-run --overwrite
* Adds some basic Keg tests

1 files changed, 85 insertions, 0 deletions

diff --git a/Library/Homebrew/test/test_keg.rb b/Library/Homebrew/test/test_keg.rb
new file mode 100644
index 000000000..c9e5990a0
--- /dev/null
+++ b/Library/Homebrew/test/test_keg.rb
@@ -0,0 +1,85 @@
+require 'testing_env'
+require 'test/testball'
+require 'keg'
+require 'stringio'
+
+class LinkTests < Test::Unit::TestCase
+  def setup
+    @formula = TestBall.new
+    shutup do
+      @formula.brew { @formula.install }
+    end
+    @keg = Keg.for @formula.prefix
+    @keg.unlink
+
+    @old_stdout = $stdout
+    $stdout = StringIO.new
+
+    FileUtils.mkpath HOMEBREW_PREFIX/"bin"
+  end
+
+  def test_linking_keg
+    assert_equal @keg.link, 3
+  end
+
+  def test_unlinking_keg
+    @keg.link
+    assert_equal @keg.unlink, 3
+  end
+
+  def test_link_dry_run
+    mode = OpenStruct.new
+    mode.dry_run = true
+
+    assert_equal @keg.link(mode), 0
+    assert !@keg.linked?
+
+    assert_equal $stdout.string, <<-EOS.undent
+      /private/tmp/testbrew/prefix/bin/hiworld
+      /private/tmp/testbrew/prefix/bin/helloworld
+      /private/tmp/testbrew/prefix/bin/goodbye_cruel_world
+      EOS
+  end
+
+  def test_linking_fails_when_already_linked
+    @keg.link
+    assert_raise RuntimeError, "Cannot link testball" do
+      @keg.link
+    end
+  end
+
+  def test_linking_fails_when_files_exist
+    FileUtils.touch HOMEBREW_PREFIX/"bin/helloworld"
+    assert_raise RuntimeError do
+      @keg.link
+    end
+  end
+
+  def test_link_overwrite
+    FileUtils.touch HOMEBREW_PREFIX/"bin/helloworld"
+    mode = OpenStruct.new
+    mode.overwrite = true
+    assert_equal @keg.link(mode), 3
+  end
+
+  def test_link_overwrite_dryrun
+    FileUtils.touch HOMEBREW_PREFIX/"bin/helloworld"
+    mode = OpenStruct.new
+    mode.overwrite = true
+    mode.dry_run = true
+
+    assert_equal @keg.link(mode), 0
+    assert !@keg.linked?
+
+    assert_equal $stdout.string, "/private/tmp/testbrew/prefix/bin/helloworld\n"
+  end
+
+  def teardown
+    @keg.unlink
+    @keg.rmtree
+
+    $stdout = @old_stdout
+
+    FileUtils.rmtree HOMEBREW_PREFIX/"bin"
+  end
+end