blame tests: don't rely on t/t4018/ directory

Refactor a test added in 9466e38 (blame: enable funcname blaming
with userdiff driver, 2020-11-01) so that the blame tests don't rely
on stealing the contents of "t/t4018/fortran-external-function".

I have another patch series that'll possibly (or not) refactor that
file, but having this test inter-dependency makes things simple in any
case by making this test more readable.

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

t/annotate-tests.sh

@@ -482,12 +482,22 @@ test_expect_success 'blame -L ^:RE (absolute: end-of-file)' '
 test_expect_success 'setup -L :funcname with userdiff driver' '
 	echo "fortran-* diff=fortran" >.gitattributes &&
 	fortran_file=fortran-external-function &&
-	orig_file="$TEST_DIRECTORY/t4018/$fortran_file" &&
-	cp "$orig_file" . &&
+	cat >$fortran_file <<-\EOF &&
+	function RIGHT(a, b) result(c)
+
+	integer, intent(in) :: ChangeMe
+	integer, intent(in) :: b
+	integer, intent(out) :: c
+
+	c = a+b
+
+	end function RIGHT
+	EOF
 	git add "$fortran_file" &&
 	GIT_AUTHOR_NAME="A" GIT_AUTHOR_EMAIL="[email protected]" \
 	git commit -m "add fortran file" &&
-	sed -e "s/ChangeMe/IWasChanged/" <"$orig_file" >"$fortran_file" &&
+	sed -e "s/ChangeMe/IWasChanged/" <"$fortran_file" >"$fortran_file".tmp &&
+	mv "$fortran_file".tmp "$fortran_file" &&
 	git add "$fortran_file" &&
 	GIT_AUTHOR_NAME="B" GIT_AUTHOR_EMAIL="[email protected]" \
 	git commit -m "change fortran file"