[PATCH 4/7] test-lib: add tee with TAP support to test-tool

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

Add a 'test-tool tee' that behaves similarly to 'tee(1)', except that
it supports sanitizing the TAP emitted on stdout.

This is done by assuming that the TAP is emitted by a friendly library
that promises to prefix valid TAP directives with what we're going to
strip with --strip-prefix="".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Makefile             |  1 +
 t/helper/test-tee.c  | 85 ++++++++++++++++++++++++++++++++++++++++++++
 t/helper/test-tool.c |  1 +
 t/helper/test-tool.h |  1 +
 4 files changed, 88 insertions(+)
 create mode 100644 t/helper/test-tee.c

diff --git a/Makefile b/Makefile
index dfb0f1000fa..d26b9d62ee9 100644
--- a/Makefile
+++ b/Makefile
@@ -742,6 +742,7 @@ TEST_BUILTINS_OBJS += test-string-list.o
 TEST_BUILTINS_OBJS += test-submodule-config.o
 TEST_BUILTINS_OBJS += test-submodule-nested-repo-config.o
 TEST_BUILTINS_OBJS += test-subprocess.o
+TEST_BUILTINS_OBJS += test-tee.o
 TEST_BUILTINS_OBJS += test-trace2.o
 TEST_BUILTINS_OBJS += test-urlmatch-normalization.o
 TEST_BUILTINS_OBJS += test-wildmatch.o
diff --git a/t/helper/test-tee.c b/t/helper/test-tee.c
new file mode 100644
index 00000000000..4ed34e9db93
--- /dev/null
+++ b/t/helper/test-tee.c
@@ -0,0 +1,85 @@
+#include "test-tool.h"
+#include "parse-options.h"
+#include "strbuf.h"
+
+static int line_has_tap(struct strbuf *line)
+{
+	/*
+	 * This is a less permissive version of
+	 * https://metacpan.org/release/Test-Harness/source/lib/TAP/Parser/Grammar.pm
+	 */
+	if (starts_with(line->buf, "ok") ||
+	    starts_with(line->buf, "not ok") ||
+	    starts_with(line->buf, "1..") ||
+	    starts_with(line->buf, "Bail out!") ||
+	    starts_with(line->buf, "TAP version") ||
+	    starts_with(line->buf, "pragma"))
+		return 1;
+	if (starts_with(line->buf, "#"))
+		/*
+		 * We're ignoring comments from now, but might treat them
+		 * specially in the future for sanctioned messaging from the
+		 * test-lib.sh.
+		 */
+		return 0;
+	return  0;
+}
+
+int cmd__tee(int argc, const char **argv)
+{
+	int tap = 0;
+	int escape_stdout = 0, escape_file = 0;
+	char *prefix = NULL;
+	size_t prefix_len = 0;
+	const char *tee_usage[] = {
+		"test-tool tee [<options>] <FILE>",
+		NULL
+	};
+	struct option options[] = {
+		OPT_BOOL(0, "escape-stdout", &escape_stdout,
+			 "escape output on stdout"),
+		OPT_BOOL(0, "escape-file", &escape_file,
+			 "escape output written to file"),
+		OPT_BOOL(0, "tap", &tap,
+			 "output is TAP"),
+		OPT_STRING(0, "prefix", &prefix, "str",
+			   "prefix to strip from the output"),
+		OPT_END()
+	};
+	struct strbuf line = STRBUF_INIT;
+	FILE *logfp = NULL;
+
+	argc = parse_options(argc, argv, NULL, options,
+			     tee_usage, PARSE_OPT_STOP_AT_NON_OPTION);
+	if (argc > 1) {
+		fprintf(stderr, "got bad option: %s\n", argv[0]);
+		usage_with_options(tee_usage, options);
+	}
+	if (prefix)
+		prefix_len = strlen(prefix);
+
+	if (argc)
+		logfp = xfopen(argv[0], "w");
+
+	while (strbuf_getline(&line, stdin) != EOF) {
+		size_t offs = 0;
+		if (prefix && starts_with(line.buf, prefix))
+			offs = prefix_len;
+
+		if (!offs && tap && line_has_tap(&line)) {
+			if (escape_stdout)
+				fprintf(stdout, "\\");
+			if (logfp && escape_file)
+				fprintf(logfp, "\\");
+		}
+
+		fprintf(stdout, "%s\n", line.buf + offs);
+		if (logfp)
+			fprintf(logfp, "%s\n", line.buf + offs);
+	}
+	strbuf_release(&line);
+	if (logfp)
+		fclose(logfp);
+
+	return 0;
+}
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index f97cd9f48a6..1876bad8f42 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -70,6 +70,7 @@ static struct test_cmd cmds[] = {
 	{ "submodule-config", cmd__submodule_config },
 	{ "submodule-nested-repo-config", cmd__submodule_nested_repo_config },
 	{ "subprocess", cmd__subprocess },
+	{ "tee", cmd__tee },
 	{ "trace2", cmd__trace2 },
 	{ "urlmatch-normalization", cmd__urlmatch_normalization },
 	{ "xml-encode", cmd__xml_encode },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index 28072c0ad5a..9b3c1f75267 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -60,6 +60,7 @@ int cmd__string_list(int argc, const char **argv);
 int cmd__submodule_config(int argc, const char **argv);
 int cmd__submodule_nested_repo_config(int argc, const char **argv);
 int cmd__subprocess(int argc, const char **argv);
+int cmd__tee(int argc, const char **argv);
 int cmd__trace2(int argc, const char **argv);
 int cmd__urlmatch_normalization(int argc, const char **argv);
 int cmd__xml_encode(int argc, const char **argv);
-- 
2.31.0.rc1.210.g0f8085a843c