Convert brew unlink test to spec.

Library/Homebrew/test/cmd/unlink_spec.rb

@@ -0,0 +1,14 @@
+describe "brew unlink", :integration_test do
+  it "unlinks a Formula" do
+    setup_test_formula "testball"
+
+    shutup do
+      expect { brew "install", "testball" }.to be_a_success
+    end
+
+    expect { brew "unlink", "--dry-run", "testball" }
+      .to output(/Would remove/).to_stdout
+      .and not_to_output.to_stderr
+      .and be_a_success
+  end
+end

Library/Homebrew/test/unlink_test.rb

@@ -1,10 +0,0 @@
-require "testing_env"
-
-class IntegrationCommandTestUnlink < IntegrationCommandTestCase
-  def test_unlink
-    setup_test_formula "testball"
-
-    cmd("install", "testball")
-    assert_match "Would remove", cmd("unlink", "--dry-run", "testball")
-  end
-end