Convert `brew --repository` test to spec.

Library/Homebrew/test/cmd/--repository_spec.rb

+describe "brew --repository", :integration_test do
+  it "prints the path of the Homebrew repository" do
+    expect { brew "--repository" }
+      .to output("#{HOMEBREW_REPOSITORY}\n").to_stdout
+      .and not_to_output.to_stderr
+      .and be_a_success
+  end
+
+  it "prints the path of a given Tap" do
+    expect { brew "--repository", "foo/bar" }
+      .to output("#{HOMEBREW_LIBRARY}/Taps/foo/homebrew-bar\n").to_stdout
+      .and not_to_output.to_stderr
+      .and be_a_success
+  end
+end

Library/Homebrew/test/repository_test.rb

-require "testing_env"
-
-class IntegrationCommandTestRepository < IntegrationCommandTestCase
-  def test_repository
-    assert_match HOMEBREW_REPOSITORY.to_s,
-                 cmd("--repository")
-    assert_match "#{HOMEBREW_LIBRARY}/Taps/foo/homebrew-bar",
-                 cmd("--repository", "foo/bar")
-  end
-end