tests: Add <tests/test.h> wrapper header and fix --gc-sections

<cmocka.h> requires a few standard headers to be explicitly included
before itself or it will throw compilation errors. Having to always
include these headers in the right order in every test is cumbersome.
Instead, this patch encapsulates the problem in a new <tests/test.h>
header that all tests should include (instead of <cmocka.h> directly).

Also fix --gc-sections in the test framework which needs to be passed
for linking, not for compiling.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: I4284d74c8673708e21a5266eb42f7b9ae19a1b12
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41045
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jan Dabros
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>

tests/Makefile.inc

@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
+testsrc = $(top)/tests
 testobj = $(obj)/tests
 
 TEST_DEFAULT_CONFIG = $(top)/configs/config.emulation_qemu_x86_i440fx
@@ -10,12 +11,12 @@ TEST_KCONFIG_DEPENDENCIES := $(testobj)/auto.conf.cmd
 TEST_KCONFIG_SPLITCONFIG := $(testobj)/config
 TEST_KCONFIG_TRISTATE := $(testobj)/tristate.conf
 
-TEST_CFLAGS = -include$(src)/include/kconfig.h \
-	-include$(src)/commonlib/bsd/include/commonlib/bsd/compiler.h \
-	-include $(src)/include/rules.h \
+TEST_CFLAGS = -include $(src)/include/kconfig.h \
+	-include $(src)/commonlib/bsd/include/commonlib/bsd/compiler.h \
+	-include $(src)/include/rules.h
 
 # Include generic test mock headers, before original ones
-TEST_CFLAGS += -Itests/include/mocks
+TEST_CFLAGS += -I$(testsrc)/include/mocks -I$(testsrc)/include
 
 TEST_CFLAGS += -I$(src)/include -I$(src)/commonlib/include \
 	-I$(src)/commonlib/bsd/include -I$(src)/arch/x86/include \
@@ -24,10 +25,10 @@ TEST_CFLAGS += -I$(src)/include -I$(src)/commonlib/include \
 TEST_CFLAGS += -I$(dir $(TEST_KCONFIG_AUTOHEADER))
 
 TEST_CFLAGS += -std=gnu11 -Os -ffunction-sections -fdata-sections \
-	-Wl,--gc-sections -fno-builtin
+	-fno-builtin
 
 # Link against Cmocka
-TEST_LDFLAGS = -lcmocka
+TEST_LDFLAGS = -lcmocka -Wl,--gc-sections
 
 # Extra attributes for unit tests, declared per test
 attributes:= srcs cflags mocks stage

tests/device/i2c-test.c

@@ -1,12 +1,8 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
-#include <stdarg.h>
-#include <stddef.h>
-#include <setjmp.h>
-#include <limits.h>
-#include <cmocka.h>
-
 #include <device/i2c_simple.h>
+#include <limits.h>
+#include <tests/test.h>
 
 /* Simulate two i2c devices, both on bus 0, each with three uint8_t regs
    implemented. */

tests/include/tests/test.h

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* This file is part of the coreboot project. */
+
+#ifndef _TESTS_TEST_H
+#define _TESTS_TEST_H
+
+/*
+ * Standard test header that should be included in all tests. For now it just encapsulates the
+ * include dependencies for Cmocka. Test-specific APIs that are so generic we would want them
+ * available everywhere could also be added here.
+ */
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <setjmp.h>
+#include <cmocka.h>
+
+#endif /* _TESTS_TEST_H */

tests/lib/string-test.c

@@ -1,11 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
-#include <stdarg.h>
-#include <stddef.h>
-#include <setjmp.h>
-#include <cmocka.h>
-
 #include <string.h>
+#include <tests/test.h>
 
 /*
  * Important note: In every particular test, don't use any string-related