Convert brew fetch test to spec.

Library/Homebrew/test/cmd/fetch_spec.rb

@@ -0,0 +1,13 @@
+describe "brew fetch", :integration_test do
+  it "downloads the Formula's URL" do
+    setup_test_formula "testball"
+
+    expect(HOMEBREW_CACHE/"testball-0.1.tbz").not_to exist
+
+    shutup do
+      expect { brew "fetch", "testball" }.to be_a_success
+    end
+
+    expect(HOMEBREW_CACHE/"testball-0.1.tbz").to exist
+  end
+end

Library/Homebrew/test/fetch_test.rb

@@ -1,11 +0,0 @@
-require "testing_env"
-
-class IntegrationCommandTestFetch < IntegrationCommandTestCase
-  def test_fetch
-    setup_test_formula "testball"
-
-    cmd("fetch", "testball")
-    assert((HOMEBREW_CACHE/"testball-0.1.tbz").exist?,
-      "The tarball should have been cached")
-  end
-end