Port helper/test-advise.c to unit-tests/t-advise.c

In the recent codebase update (8bf6fbd (Merge branch
'js/doc-unit-tests', 2023-12-09)), a new unit testing framework was
merged, providing a standardized approach for testing C code. Prior to
this update, some unit tests relied on the test helper mechanism,
lacking a dedicated unit testing framework. It's more natural to perform
these unit tests using the new unit test framework.

This commit migrates the unit tests for advise_if_enabled functionality
from the legacy approach using the test-tool command `test-tool advise`
in t/helper/test-advise.c to the new unit testing framework
(t/unit-tests/test-lib.h).

The migration involves refactoring the tests to utilize the testing
macros provided by the framework (TEST() and check_*()).

Mentored-by: Christian Couder <[email protected]>
Signed-off-by: Achu Luma <[email protected]>

Makefile

@@ -783,7 +783,6 @@ X =
 
 PROGRAMS += $(patsubst %.o,git-%$X,$(PROGRAM_OBJS))
 
-TEST_BUILTINS_OBJS += test-advise.o
 TEST_BUILTINS_OBJS += test-bitmap.o
 TEST_BUILTINS_OBJS += test-bloom.o
 TEST_BUILTINS_OBJS += test-bundle-uri.o
@@ -1342,6 +1341,7 @@ THIRD_PARTY_SOURCES += sha1dc/%
 UNIT_TEST_PROGRAMS += t-basic
 UNIT_TEST_PROGRAMS += t-mem-pool
 UNIT_TEST_PROGRAMS += t-strbuf
+UNIT_TEST_PROGRAMS += t-advise
 UNIT_TEST_PROGS = $(patsubst %,$(UNIT_TEST_BIN)/%$X,$(UNIT_TEST_PROGRAMS))
 UNIT_TEST_OBJS = $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(UNIT_TEST_PROGRAMS))
 UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/test-lib.o

t/helper/test-tool.c

@@ -10,7 +10,6 @@ static const char * const test_tool_usage[] = {
 };
 
 static struct test_cmd cmds[] = {
-	{ "advise", cmd__advise_if_enabled },
 	{ "bitmap", cmd__bitmap },
 	{ "bloom", cmd__bloom },
 	{ "bundle-uri", cmd__bundle_uri },

t/helper/test-tool.h

@@ -3,7 +3,6 @@
 
 #include "git-compat-util.h"
 
-int cmd__advise_if_enabled(int argc, const char **argv);
 int cmd__bitmap(int argc, const char **argv);
 int cmd__bloom(int argc, const char **argv);
 int cmd__bundle_uri(int argc, const char **argv);

t/unit-tests/t-advise.c

@@ -0,0 +1,56 @@
+#include "test-lib.h"
+#include "advice.h"
+#include "config.h"
+#include "setup.h"
+#include "strbuf.h"
+
+static const char expect_advice_msg[] = "hint: This is a piece of advice\n"
+					"hint: Disable this message with \"git config advice.nestedTag false\"\n";
+static const char advice_msg[] = "This is a piece of advice";
+static const char out_file[] = "./output.txt";
+
+
+static void check_advise_if_enabled(const char *argv, const char *conf_val, const char *expect) {
+	FILE *file;
+	struct strbuf actual = STRBUF_INIT;
+
+	if (conf_val)
+		git_default_advice_config("advice.nestedTag", conf_val);
+
+	file = freopen(out_file, "w", stderr);
+	if (!check(!!file)) {
+		test_msg("Error opening file %s", out_file);
+		return;
+	}
+
+	advise_if_enabled(ADVICE_NESTED_TAG, "%s", argv);
+	fclose(file);
+
+	if (!check(strbuf_read_file(&actual, out_file, 0) >= 0)) {
+		test_msg("Error reading file %s", out_file);
+		strbuf_release(&actual);
+		return;
+	}
+
+	check_str(actual.buf, expect);
+	strbuf_release(&actual);
+
+	// Delete the output.txt file after the check is done
+	if (!check(remove(out_file) == 0))
+		test_msg("Error deleting %s", out_file);
+}
+
+int cmd_main(int argc, const char **argv) {
+	setenv("GIT_DISCOVERY_ACROSS_FILESYSTEM", "1", 1);
+	setenv("TERM", "dumb", 1);
+	setup_git_directory();
+
+	TEST(check_advise_if_enabled(advice_msg, NULL, expect_advice_msg),
+		"advice should be printed when config variable is unset");
+	TEST(check_advise_if_enabled(advice_msg, "true", expect_advice_msg),
+		"advice should be printed when config variable is set to true");
+	TEST(check_advise_if_enabled(advice_msg, "false", ""),
+		"advice should not be printed when config variable is set to false");
+
+	return test_done();
+}