Merge branch 'js/difftool-builtin'

A few hot-fixes to C-rewrite of "git difftool".

* js/difftool-builtin:
t7800: simplify basic usage test
difftool: fix bug when printing usage

diff --combined t/t7800-difftool.sh
index aa0ef02597f051b17747df4c9cf3d4b50563ed69,3d728e296d3e3b76cbde00960e12f1731cabd887..97bae54d8343dc2cdfb0ea259b0f231429468c78
--- 1/t/t7800-difftool.sh
--- 2/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@@ -23,6 -23,18 +23,18 @@@ prompt_given (
        test "$prompt" = "Launch 'test-tool' [Y/n]? branch"
  }
  
+ test_expect_success 'basic usage requires no repo' '
+       test_expect_code 129 git difftool -h >output &&
+       grep ^usage: output &&
+       # create a ceiling directory to prevent Git from finding a repo
+       mkdir -p not/repo &&
+       test_when_finished rm -r not &&
+       test_expect_code 129 \
+       env GIT_CEILING_DIRECTORIES="$(pwd)/not" \
+       git -C not/repo difftool -h >output &&
+       grep ^usage: output
+ '
+ 
  # Create a file on master and change it on branch
  test_expect_success 'setup' '
        echo master >file &&
@@@ -374,7 -386,6 +386,7 @@@ test_expect_success 'setup change in su
        echo master >sub/sub &&
        git add sub/sub &&
        git commit -m "added sub/sub" &&
 +      git tag v1 &&
        echo test >>file &&
        echo test >>sub/sub &&
        git add file sub/sub &&
@@@ -410,49 -421,12 +422,49 @@@ run_dir_diff_test 'difftool --dir-diff 
        grep file output
  '
  
 -run_dir_diff_test 'difftool --dir-diff from subdirectory' '
 +run_dir_diff_test 'difftool --dir-diff branch from subdirectory' '
        (
                cd sub &&
                git difftool --dir-diff $symlinks --extcmd ls branch >output &&
 -              grep sub output &&
 -              grep file output
 +              # "sub" must only exist in "right"
 +              # "file" and "file2" must be listed in both "left" and "right"
 +              test "1" = $(grep sub output | wc -l) &&
 +              test "2" = $(grep file"$" output | wc -l) &&
 +              test "2" = $(grep file2 output | wc -l)
 +      )
 +'
 +
 +run_dir_diff_test 'difftool --dir-diff v1 from subdirectory' '
 +      (
 +              cd sub &&
 +              git difftool --dir-diff $symlinks --extcmd ls v1 >output &&
 +              # "sub" and "file" exist in both v1 and HEAD.
 +              # "file2" is unchanged.
 +              test "2" = $(grep sub output | wc -l) &&
 +              test "2" = $(grep file output | wc -l) &&
 +              test "0" = $(grep file2 output | wc -l)
 +      )
 +'
 +
 +run_dir_diff_test 'difftool --dir-diff branch from subdirectory w/ pathspec' '
 +      (
 +              cd sub &&
 +              git difftool --dir-diff $symlinks --extcmd ls branch -- .>output &&
 +              # "sub" only exists in "right"
 +              # "file" and "file2" must not be listed
 +              test "1" = $(grep sub output | wc -l) &&
 +              test "0" = $(grep file output | wc -l)
 +      )
 +'
 +
 +run_dir_diff_test 'difftool --dir-diff v1 from subdirectory w/ pathspec' '
 +      (
 +              cd sub &&
 +              git difftool --dir-diff $symlinks --extcmd ls v1 -- .>output &&
 +              # "sub" exists in v1 and HEAD
 +              # "file" is filtered out by the pathspec
 +              test "2" = $(grep sub output | wc -l) &&
 +              test "0" = $(grep file output | wc -l)
        )
  '