[PATCH 02/20] test library: add a test_byte_count

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

This new function is like test_line_count except it uses "wc -c"
instead of "wc -l". Perhaps this should be a parameter, but I don't
see us needing "wc -m" (chars), "wc -w" (words) etc.

Change a couple of existing tests that use this, I expect to use this
in later patches when adding more tests.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/README                   |  4 ++++
 t/t6006-rev-list-format.sh |  6 ++----
 t/test-lib-functions.sh    | 23 +++++++++++++++++++++++
 3 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/t/README b/t/README
index eede11d649..3139c27e4e 100644
--- a/t/README
+++ b/t/README
@@ -728,6 +728,10 @@ library for your script to use.
    Check whether the <expected> rev points to the same commit as the
    <actual> rev.
 
+ - test_byte_count (= | -lt | -ge | ...) <length> <file>
+
+   Check whether a file has the number of bytes it is expected to.
+
  - test_line_count (= | -lt | -ge | ...) <length> <file>
 
    Check whether a file has the number of lines it is expected to.
diff --git a/t/t6006-rev-list-format.sh b/t/t6006-rev-list-format.sh
index ec42c2f779..ec068c55ab 100755
--- a/t/t6006-rev-list-format.sh
+++ b/t/t6006-rev-list-format.sh
@@ -456,14 +456,12 @@ test_expect_success '--abbrev' '
 
 test_expect_success '%H is not affected by --abbrev-commit' '
 	git log -1 --format=%H --abbrev-commit --abbrev=20 HEAD >actual &&
-	len=$(wc -c <actual) &&
-	test $len = 41
+	test_byte_count = 41 actual
 '
 
 test_expect_success '%h is not affected by --abbrev-commit' '
 	git log -1 --format=%h --abbrev-commit --abbrev=20 HEAD >actual &&
-	len=$(wc -c <actual) &&
-	test $len = 21
+	test_byte_count = 21 actual
 '
 
 test_expect_success '"%h %gD: %gs" is same as git-reflog' '
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 2b2181dca0..91a566f14e 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -589,6 +589,29 @@ test_path_is_missing () {
 	fi
 }
 
+# test_byte_count checks that a file has the number of bytes it
+# ought to. For example:
+#
+#	test_expect_success 'produce exactly one byte of output' '
+#		do something >output &&
+#		test_byte_count = 1 output
+#	'
+#
+# is like "test $(wc -c <output) = 1" except that it passes the
+# output through when the number of bytes is wrong.
+
+test_byte_count () {
+	if test $# != 3
+	then
+		error "bug in the test script: not 3 parameters to test_byte_count"
+	elif ! test $(wc -c <"$3") "$1" "$2"
+	then
+		echo "test_byte_count: byte count for $3 !$1 $2"
+		cat "$3"
+		return 1
+	fi
+}
+
 # test_line_count checks that a file has the number of lines it
 # ought to. For example:
 #
-- 
2.17.0.290.gded63e768a