Add test runner

This patch adds a "magic" test runner which discovers all test cases in the
executable into which it is linked. This is achieved through the use of a
special macro used to declare tests, so that they are added onto a linker-
generated list. The linker list logic is largely taken from U-Boot source code,
with minor some tweaks made.

This linker-generated list is then used at runtime in order to pick out every
test case which can be run, resulting in a cross-file "suite" of unity unit
tests, rather than separate test executables per module. A sample test module,
test_test.c is provided to illustrate the test runner's ability to correctly
discover tests across multiple translation units.

6 files changed, 76 insertions, 17 deletions

diff --git a/Makefile b/Makefile
index e05f490..73d957d 100644
--- a/Makefile
+++ b/Makefile
@@ -51,9 +51,11 @@ clean:
 
 test: \
 	$(UNITY_O) \
+	build/native/test_runner.o \
 	build/native/test_util.o \
+	build/native/test_test.o \
 	build/native/util.o
-	$(CC) $(LDFLAGS) -o $@ $^
+	$(CC) $(LDFLAGS) -Wl,-T,linker_list.lds -o $@ $^
 	./$@
 
 # ELF for real hardware. No mock/sim hardware included (except barometer,
diff --git a/linker_list.lds b/linker_list.lds
new file mode 100644
index 0000000..bb70bd8
--- /dev/null
+++ b/linker_list.lds
@@ -0,0 +1,8 @@
+SECTIONS {
+	__test_runner_list_start = .;
+	.test_runner_list : {
+		KEEP(*(SORT(.test_runner_list*)));
+	}
+	__test_runner_list_end = .;
+}
+INSERT BEFORE .bss;
diff --git a/test_runner.c b/test_runner.c
new file mode 100644
index 0000000..9d3ad65
--- /dev/null
+++ b/test_runner.c
@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+#include "test_runner.h"
+#include "unity.h"
+
+/* unity requires these, even if empty */
+void setUp(){};
+void tearDown(){};
+
+int main(void)
+{
+	struct test_fn *tests = list_head(struct test_fn, test_list);
+	size_t count = list_entry_count(struct test_fn, test_list);
+	printf("Suite has %zd tests\n", count);
+	UNITY_BEGIN();
+	for (size_t i = 0; i < count; i++) {
+		UnitySetTestFile(tests[i].file);
+		UnityDefaultTestRun(tests[i].fn, tests[i].name, tests[i].line);
+	}
+	UNITY_END();
+}
diff --git a/test_runner.h b/test_runner.h
new file mode 100644
index 0000000..5b891b0
--- /dev/null
+++ b/test_runner.h
@@ -0,0 +1,32 @@
+#pragma once
+
+/* Linker-generated lists derived from U-Boot source `include/linker_lists.h`
+ * with minor modification to store function pointers */
+#define list_head(entry_type, list_name) \
+	({ static char head[0] __attribute__((__aligned__(4), unused, section(".test_runner_list_2_"#list_name"_1")));(entry_type*)&head; })
+
+#define list_tail(entry_type, list_name) \
+	({ static char tail[0] __attribute__((__aligned__(4), unused, section(".test_runner_list_2_"#list_name"_3")));(entry_type*)&tail; })
+
+#define list_entry_count(entry_type, list_name) \
+	({ \
+		entry_type* head = list_head(entry_type, list_name); \
+		entry_type* tail = list_tail(entry_type, list_name); \
+		(size_t)(tail - head); \
+	})
+
+#define list_entry(entry_type, list_name, entry_name) \
+	entry_type _test_runner_list_2_##list_name_2_##entry_name __attribute__((__aligned__(4), unused, section(".test_runner_list_2_"#list_name"_2_"#entry_name)))
+
+#define RUNNER_DECLARE_TEST(test_name) \
+	void test_name(void);\
+	list_entry(struct test_fn, test_list, test_name) = { .name = #test_name, .file = __FILE__, .line = __LINE__, .fn = test_name}; \
+	void test_name(void)
+
+struct test_fn {
+	const char *name;
+	const char *file;
+	int line;
+	void (*fn)();
+};
+
diff --git a/test_test.c b/test_test.c
new file mode 100644
index 0000000..9a78c3e
--- /dev/null
+++ b/test_test.c
@@ -0,0 +1,7 @@
+#include "test_runner.h"
+#include "unity.h"
+
+RUNNER_DECLARE_TEST(test_test)
+{
+	TEST_ASSERT_EQUAL(0,0);
+}
diff --git a/test_util.c b/test_util.c
index 81c3db7..c6b9b83 100644
--- a/test_util.c
+++ b/test_util.c
@@ -1,14 +1,13 @@
 #include <string.h>
 
+#include "test_runner.h"
 #include "unity.h"
 #include "util.h"
 
-void setUp(){};
-void tearDown(){};
 
 /* blank_to_eol should pad a buffer with spaces as far as it can, after an
  * existing string therein, without overrunning, while still terminating */
-void test_blank_to_eol_happy(void)
+RUNNER_DECLARE_TEST(test_blank_to_eol_happy)
 {
 	char buf[11] = "hello";
 	blank_to_eol(buf, sizeof(buf));
@@ -17,7 +16,7 @@ void test_blank_to_eol_happy(void)
 
 /* blanking an empty string to end of buffer should fill entire buffer with
  * spaces until the last byte, which should be null terminator */
-void test_blank_to_eol_empty(void)
+RUNNER_DECLARE_TEST(test_blank_to_eol_empty)
 {
 	char buf[5] = "";
 	blank_to_eol(buf, sizeof(buf));
@@ -25,7 +24,7 @@ void test_blank_to_eol_empty(void)
 }
 
 /* blanking should not overrun the specified buffer size at all */
-void test_blank_to_eol_no_overrun(void)
+RUNNER_DECLARE_TEST(test_blank_to_eol_no_overrun)
 {
 	char buf[20] = {
 		'h', 'e', 'l', 'l', 'o', '\0',
@@ -41,7 +40,7 @@ void test_blank_to_eol_no_overrun(void)
 /* blanking a buffer which already has no '\0' within it should result in the
  * buffer being terminated, truncating contents minimally as necessary to fit
  * a '\0' */
-void test_blank_to_eol_overrun(void)
+RUNNER_DECLARE_TEST(test_blank_to_eol_overrun)
 {
 	char buf[20] = "hello, world!";
 	blank_to_eol(buf, 6);
@@ -50,13 +49,3 @@ void test_blank_to_eol_overrun(void)
 	 * doesn't test OOB reads, only writes */
 	TEST_ASSERT_EQUAL_STRING(" world!", &buf[6]);
 }
-
-int main(void)
-{
-	UNITY_BEGIN();
-	RUN_TEST(test_blank_to_eol_happy);
-	RUN_TEST(test_blank_to_eol_empty);
-	RUN_TEST(test_blank_to_eol_no_overrun);
-	RUN_TEST(test_blank_to_eol_overrun);
-	return UNITY_END();
-}