Convert `brew log` test to spec.

Library/Homebrew/test/log_formula_test.rb → Library/Homebrew/test/cmd/log_spec.rb

-require "testing_env"
+describe "brew log", :integration_test do
+  it "shows the Git log for the Homebrew repository when no argument is given" do
+    HOMEBREW_REPOSITORY.cd do
+      shutup do
+        system "git", "init"
+        system "git", "commit", "--allow-empty", "-m", "This is a test commit"
+      end
+    end
 
-class IntegrationCommandTestLogFormula < IntegrationCommandTestCase
-  def test_log_formula
-    core_tap = CoreTap.new
+    expect { brew "log" }
+      .to output(/This is a test commit/).to_stdout
+      .and not_to_output.to_stderr
+      .and be_a_success
+  end
+
+  it "shows the Git log for a given Formula" do
     setup_test_formula "testball"
 
+    core_tap = CoreTap.new
     core_tap.path.cd do
       shutup do
         system "git", "init"
@@ -19,9 +31,11 @@ class IntegrationCommandTestLogFormula < IntegrationCommandTestCase
       system "git", "clone", "--depth=1", core_tap_url, shallow_tap.path
     end
 
-    assert_match "This is a test commit for Testball",
-                 cmd("log", "#{shallow_tap}/testball")
-    assert_predicate shallow_tap.path/".git/shallow", :exist?,
-                     "A shallow clone should have been created."
+    expect { brew "log", "#{shallow_tap}/testball" }
+      .to output(/This is a test commit for Testball/).to_stdout
+      .and output(/Warning: The git repository is a shallow clone/).to_stderr
+      .and be_a_success
+
+    expect(shallow_tap.path/".git/shallow").to exist, "A shallow clone should have been created."
   end
 end

Library/Homebrew/test/log_test.rb

-require "testing_env"
-
-class IntegrationCommandTestLog < IntegrationCommandTestCase
-  def test_log
-    FileUtils.cd HOMEBREW_REPOSITORY do
-      shutup do
-        system "git", "init"
-        system "git", "commit", "--allow-empty", "-m", "This is a test commit"
-      end
-    end
-    assert_match "This is a test commit", cmd("log")
-  end
-end