help: introduce option --exclude-guides

Introduce option --exclude-guides to the help command.  With this option
being passed, "git help" will open man pages only for actual commands.

Since we know it is a command, we can use function help_unknown_command
to give the user advice on typos.

Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/help.c

@@ -37,8 +37,10 @@ static int show_all = 0;
 static int show_guides = 0;
 static unsigned int colopts;
 static enum help_format help_format = HELP_FORMAT_NONE;
+static int exclude_guides;
 static struct option builtin_help_options[] = {
 	OPT_BOOL('a', "all", &show_all, N_("print all available commands")),
+	OPT_HIDDEN_BOOL(0, "exclude-guides", &exclude_guides, N_("exclude guides")),
 	OPT_BOOL('g', "guides", &show_guides, N_("print list of useful guides")),
 	OPT_SET_INT('m', "man", &help_format, N_("show man page"), HELP_FORMAT_MAN),
 	OPT_SET_INT('w', "web", &help_format, N_("show manual in web browser"),
@@ -426,10 +428,29 @@ static void list_common_guides_help(void)
 	putchar('\n');
 }
 
+static const char *check_git_cmd(const char* cmd)
+{
+	char *alias;
+
+	if (is_git_command(cmd))
+		return cmd;
+
+	alias = alias_lookup(cmd);
+	if (alias) {
+		printf_ln(_("`git %s' is aliased to `%s'"), cmd, alias);
+		free(alias);
+		exit(0);
+	}
+
+	if (exclude_guides)
+		return help_unknown_cmd(cmd);
+
+	return cmd;
+}
+
 int cmd_help(int argc, const char **argv, const char *prefix)
 {
 	int nongit;
-	char *alias;
 	enum help_format parsed_help_format;
 
 	argc = parse_options(argc, argv, prefix, builtin_help_options,
@@ -469,12 +490,7 @@ int cmd_help(int argc, const char **argv, const char *prefix)
 	if (help_format == HELP_FORMAT_NONE)
 		help_format = parse_help_format(DEFAULT_HELP_FORMAT);
 
-	alias = alias_lookup(argv[0]);
-	if (alias && !is_git_command(argv[0])) {
-		printf_ln(_("`git %s' is aliased to `%s'"), argv[0], alias);
-		free(alias);
-		return 0;
-	}
+	argv[0] = check_git_cmd(argv[0]);
 
 	switch (help_format) {
 	case HELP_FORMAT_NONE:

t/t0012-help.sh

@@ -0,0 +1,44 @@
+#!/bin/sh
+
+test_description='help'
+
+. ./test-lib.sh
+
+configure_help () {
+	test_config help.format html &&
+
+	# Unless the path has "://" in it, Git tries to make sure
+	# the documentation directory locally exists. Avoid it as
+	# we are only interested in seeing an attempt to correctly
+	# invoke a help browser in this test.
+	test_config help.htmlpath test://html &&
+
+	# Name a custom browser
+	test_config browser.test.cmd ./test-browser &&
+	test_config help.browser test
+}
+
+test_expect_success "setup" '
+	# Just write out which page gets requested
+	write_script test-browser <<-\EOF
+	echo "$*" >test-browser.log
+	EOF
+'
+
+test_expect_success "works for commands and guides by default" '
+	configure_help &&
+	git help status &&
+	echo "test://html/git-status.html" >expect &&
+	test_cmp expect test-browser.log &&
+	git help revisions &&
+	echo "test://html/gitrevisions.html" >expect &&
+	test_cmp expect test-browser.log
+'
+
+test_expect_success "--exclude-guides does not work for guides" '
+	>test-browser.log &&
+	test_must_fail git help --exclude-guides revisions &&
+	test_must_be_empty test-browser.log
+'
+
+test_done