test-lib: introduce test_line_count to measure files

jrn · gitster · commit fb3340a6a7a9 · 2010-11-09T14:47:17.000-08:00
Some tests check their output with code like the following: test "$(git ls-files -u B | wc -l)" -eq 3 || { echo "BAD: should have left stages for B" return 1 } The verbose failure condition is used because test, unlike diff, does not print any useful information about the nature of the failure when it fails. Introduce a test_line_count function to help. If used like git ls-files -u B >output && test_line_count -eq 3 output it will produce output like test_line_count: line count for output !-eq 3 100644 b023018cabc396e7692c70bbf5784a93d3f738ab 2 hi.c 100644 45b983b 3 hi.c on failure. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/README b/t/README
@@ -500,6 +500,10 @@ library for your script to use.
    <expected> file.  This behaves like "cmp" but produces more
    helpful output when the test is run with "-v" option.
 
+ - test_line_count (= | -lt | -ge | ...) <length> <file>
+
+   Check whether a file has the length it is expected to.
+
  - test_path_is_file <file> [<diagnosis>]
    test_path_is_dir <dir> [<diagnosis>]
    test_path_is_missing <path> [<diagnosis>]
diff --git a/t/test-lib.sh b/t/test-lib.sh
@@ -598,6 +598,28 @@ test_path_is_missing () {
 	fi
 }
 
+# test_line_count checks that a file has the number of lines it
+# ought to. For example:
+#
+#	test_expect_success 'produce exactly one line of output' '
+#		do something >output &&
+#		test_line_count = 1 output
+#	'
+#
+# is like "test $(wc -l <output) = 1" except that it passes the
+# output through when the number of lines is wrong.
+
+test_line_count () {
+	if test $# != 3
+	then
+		error "bug in the test script: not 3 parameters to test_line_count"
+	elif ! test $(wc -l <"$3") "$1" "$2"
+	then
+		echo "test_line_count: line count for $3 !$1 $2"
+		cat "$3"
+		return 1
+	fi
+}
 
 # This is not among top-level (test_expect_success | test_expect_failure)
 # but is a prefix that can be used in the test script, like:
