which: tests added

Closes Homebrew/homebrew#42954.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

Library/Homebrew/test/test_utils.rb

 require "testing_env"
+require "tempfile"
 
 class UtilTests < Homebrew::TestCase
+
+  def setup
+    @dir = Pathname.new(mktmpdir)
+  end
+
+  def teardown
+    @dir.rmtree
+  end
+
   def test_put_columns_empty
     # Issue #217 put columns with new results fails.
     assert_silent { puts_columns [] }
   end
 
+  def test_which
+    cmd = @dir/"foo"
+    FileUtils.touch cmd
+    cmd.chmod 0744
+    assert_equal Pathname.new(cmd),
+      which(File.basename(cmd), File.dirname(cmd))
+  end
+
+  def test_which_skip_non_executables
+    cmd = @dir/"foo"
+    FileUtils.touch cmd
+    assert_nil which(File.basename(cmd), File.dirname(cmd))
+  end
+
+  def test_which_skip_malformed_path
+    # 'which' should not fail if a path is malformed
+    # see https://github.com/Homebrew/homebrew/issues/32789 for an example
+    cmd = @dir/"foo"
+    FileUtils.touch cmd
+    cmd.chmod 0744
+
+    # ~~ will fail because ~foo resolves to foo's home and there is no '~' user
+    # here
+    assert_equal Pathname.new(cmd),
+      which(File.basename(cmd), "~~#{File::PATH_SEPARATOR}#{File.dirname(cmd)}")
+  end
+
   def test_popen_read
     out = Utils.popen_read("/bin/sh", "-c", "echo success").chomp
     assert_equal "success", out