add some unit tests

Makefile

@@ -0,0 +1,7 @@
+.PHONY: all
+all:
+	./rscons
+
+.PHONY: test
+test: all
+	./build/e.1/tests

Rsconscript

@@ -0,0 +1,7 @@
+build do
+  Environment.new do |env|
+    sources = glob("src/**/*.c")
+    env["CPPPATH"] += glob("src/**")
+    env.Program("^/tests", sources + glob("test/**/*.c"))
+  end
+end

test/test_jairee.c

@@ -0,0 +1,42 @@
+#include "jairee.h"
+#include <stdio.h>
+
+#define TEST(x) Test(#x, x, __FILE__, __LINE__)
+
+static int n_tests_passed;
+static int n_tests_failed;
+
+static void Test(const char * message, int result, const char * file, int line)
+{
+    if (result)
+    {
+        n_tests_passed++;
+    }
+    else
+    {
+        fprintf(stderr, "Test failure at %s:%d: \"%s\"\n", file, line, message);
+        n_tests_failed++;
+    }
+}
+
+static void test_asciiz_string()
+{
+    jairee_string_t * s = jairee_string_from_asciiz("Test String");
+    size_t offset = 0;
+    TEST(s->len == 11u);
+    TEST(s->decode(s->str, &offset) == 'T');
+    TEST(offset == 1u);
+    offset = 10u;
+    TEST(s->decode(s->str, &offset) == 'g');
+    TEST(offset == 11u);
+    jairee_string_free(s);
+}
+
+int main(int argc, char * argv[])
+{
+    test_asciiz_string();
+
+    printf("%d/%d tests passed\n", n_tests_passed, n_tests_passed + n_tests_failed);
+
+    return n_tests_failed == 0 ? 0 : 1;
+}