'
+test_expect_success SYMLINKS 'typechange diff' '
+ rm -f file &&
+ ln -s elif file &&
+ GIT_EXTERNAL_DIFF=echo git diff | {
+ read path oldfile oldhex oldmode newfile newhex newmode &&
+ test "z$path" = zfile &&
+ test "z$oldmode" = z100644 &&
+ test "z$newhex" = "z$_z40" &&
+ test "z$newmode" = z120000 &&
+ oh=$(git rev-parse --verify HEAD:file) &&
+ test "z$oh" = "z$oldhex"
+ } &&
+ GIT_EXTERNAL_DIFF=echo git diff --no-ext-diff >actual &&
+ git diff >expect &&
+ test_cmp expect actual
+'
+
+test_expect_success 'diff.external' '
+ git reset --hard &&
+ echo third >file &&
+ test_config diff.external echo &&
+ git diff | {
+ read path oldfile oldhex oldmode newfile newhex newmode &&
+ test "z$path" = zfile &&
+ test "z$oldmode" = z100644 &&
+ test "z$newhex" = "z$_z40" &&
+ test "z$newmode" = z100644 &&
+ oh=$(git rev-parse --verify HEAD:file) &&
+ test "z$oh" = "z$oldhex"
+ }
+'
+
+test_expect_success 'diff.external should apply only to diff' '
+ test_config diff.external echo &&
+ git log -p -1 HEAD |
+ grep "^diff --git a/file b/file"
+'
+
+test_expect_success 'diff.external and --no-ext-diff' '
+ test_config diff.external echo &&
+ git diff --no-ext-diff |
+ grep "^diff --git a/file b/file"
+'
+
test_expect_success 'diff attribute' '
+ git reset --hard &&
+ echo third >file &&
git config diff.parrot.command echo &&
'
+test_expect_success 'GIT_EXTERNAL_DIFF trumps diff.external' '
+ >.gitattributes &&
+ test_config diff.external "echo ext-global" &&
+ GIT_EXTERNAL_DIFF="echo ext-env" git diff | grep ext-env
+'
+
+test_expect_success 'attributes trump GIT_EXTERNAL_DIFF and diff.external' '
+ test_config diff.foo.command "echo ext-attribute" &&
+ test_config diff.external "echo ext-global" &&
+ echo "file diff=foo" >.gitattributes &&
+ GIT_EXTERNAL_DIFF="echo ext-env" git diff | grep ext-attribute
+'
+
test_expect_success 'no diff with -diff' '
echo >.gitattributes "file -diff" &&
git diff | grep Binary