tests: check all our Bash code for syntax errors

Additionally include our bootstrap code in `brew.sh`, Bash utilities in
`utils.sh` and `utils/*.sh`, `superenv` shims, and the Bash completion.

Closes Homebrew#654.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

Library/Homebrew/test/test_bash.rb

@@ -1,20 +1,34 @@
 require "testing_env"
 
 class BashTests < Homebrew::TestCase
-  def assert_valid_bash_syntax(files)
-    output = Utils.popen_read("/bin/bash -n #{files} 2>&1")
+  def assert_valid_bash_syntax(file)
+    output = Utils.popen_read("/bin/bash -n #{file} 2>&1")
     assert $?.success?, output
   end
 
   def test_bin_brew
-    assert_valid_bash_syntax "#{HOMEBREW_LIBRARY_PATH.parent.parent}/bin/brew"
+    assert_valid_bash_syntax HOMEBREW_LIBRARY_PATH.parent.parent/"bin/brew"
   end
 
-  def test_bash_cmds
-    %w[cmd dev-cmd].each do |dir|
-      Dir["#{HOMEBREW_LIBRARY_PATH}/#{dir}/*.sh"].each do |cmd|
-        assert_valid_bash_syntax cmd
-      end
+  def test_bash_code
+    Pathname.glob("#{HOMEBREW_LIBRARY_PATH}/**/*.sh").each do |pn|
+      pn_relative = pn.relative_path_from(HOMEBREW_LIBRARY_PATH)
+      next if pn_relative.to_s.start_with?("shims/", "test/", "vendor/")
+      assert_valid_bash_syntax pn
+    end
+  end
+
+  def test_bash_completion
+    script = HOMEBREW_LIBRARY_PATH.parent.parent/"etc/bash_completion.d/brew"
+    assert_valid_bash_syntax script
+  end
+
+  def test_bash_shims
+    # These have no file extension, but can be identified by their shebang.
+    (HOMEBREW_LIBRARY_PATH/"shims").find do |pn|
+      next if pn.directory? || pn.symlink?
+      next unless pn.executable? && pn.read(12) == "#!/bin/bash\n"
+      assert_valid_bash_syntax pn
     end
   end
 end