t0027: support NATIVE_CRLF platforms

t0027 expects the native end-of-lines to be a single line feed
character.  On Windows, however, we set it to a carriage return
character followed by a line feed character.  Thus, we have to
modify t0027 to expect different warnings depending on the
end-of-line markers.

Adjust the check of the warnings and use these macros:

  WILC:  Warn if LF becomes CRLF
  WICL:  Warn if CRLF becomes LF
  WAMIX: Mixed line endings: either CRLF->LF or LF->CRLF

Improve the information given by check_warning().

Use test_cmp to show which warning is missing (or shouldn't be
there).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0027-auto-crlf.sh

@@ -57,15 +57,13 @@ create_gitattributes () {
 
 check_warning () {
 	case "$1" in
-	LF_CRLF) grep "LF will be replaced by CRLF" $2;;
-	CRLF_LF) grep "CRLF will be replaced by LF" $2;;
-	'')
-		>expect
-		grep "will be replaced by" $2 >actual
-		test_cmp expect actual
-		;;
-	*) false ;;
+	LF_CRLF) echo "warning: LF will be replaced by CRLF" >"$2".expect ;;
+	CRLF_LF) echo "warning: CRLF will be replaced by LF" >"$2".expect ;;
+	'')	                                                 >"$2".expect ;;
+	*) echo >&2 "Illegal 1": "$1" ; return false ;;
 	esac
+	grep "will be replaced by" "$2" | sed -e "s/\(.*\) in [^ ]*$/\1/" >"$2".actual
+	test_cmp "$2".expect "$2".actual
 }
 
 commit_check_warn () {
@@ -169,20 +167,34 @@ test_expect_success 'setup master' '
 warn_LF_CRLF="LF will be replaced by CRLF"
 warn_CRLF_LF="CRLF will be replaced by LF"
 
+# WILC stands for "Warn if (this OS) converts LF into CRLF".
+# WICL: Warn if CRLF becomes LF
+# WAMIX: Mixed line endings: either CRLF->LF or LF->CRLF
+if test_have_prereq NATIVE_CRLF
+then
+	WILC=LF_CRLF
+	WICL=
+	WAMIX=LF_CRLF
+else
+	WILC=
+	WICL=CRLF_LF
+	WAMIX=CRLF_LF
+fi
+
 test_expect_success 'commit files empty attr' '
 	commit_check_warn false ""     ""        ""        ""        ""        "" &&
 	commit_check_warn true  ""     "LF_CRLF" ""        "LF_CRLF" ""        "" &&
 	commit_check_warn input ""     ""        "CRLF_LF" "CRLF_LF" ""        ""
 '
 
 test_expect_success 'commit files attr=auto' '
-	commit_check_warn false "auto" ""        "CRLF_LF" "CRLF_LF" ""        "" &&
+	commit_check_warn false "auto" "$WILC"  "$WICL"    "$WAMIX"  ""        "" &&
 	commit_check_warn true  "auto" "LF_CRLF" ""        "LF_CRLF" ""        "" &&
 	commit_check_warn input "auto" ""        "CRLF_LF" "CRLF_LF" ""        ""
 '
 
 test_expect_success 'commit files attr=text' '
-	commit_check_warn false "text" ""        "CRLF_LF" "CRLF_LF" ""        "CRLF_LF" &&
+	commit_check_warn false "text" "$WILC"  "$WICL"    "$WAMIX"  "$WILC"  "$WICL" &&
 	commit_check_warn true  "text" "LF_CRLF" ""        "LF_CRLF" "LF_CRLF" ""        &&
 	commit_check_warn input "text" ""        "CRLF_LF" "CRLF_LF" ""        "CRLF_LF"
 '