test: add a test that reads one utf8 codepoint from a file

test/cat1.c

@@ -0,0 +1,39 @@
+#include <blue/core/stream.h>
+#include <blue/core/stringstream.h>
+#include <blue/ds/string.h>
+#include <blue/io/file.h>
+#include <blue/io/path.h>
+#include <stdio.h>
+
+int main(int argc, const char **argv)
+{
+	if (argc < 2) {
+		return -1;
+	}
+
+	const char *path_cstr = argv[1];
+	b_path *path = b_path_create_from_cstr(path_cstr);
+
+	b_file *src = NULL;
+	b_result result = b_file_open(NULL, path, B_FILE_READ_ONLY, &src);
+	if (b_result_is_error(result)) {
+		b_throw(result);
+		return -1;
+	}
+
+	b_wchar c;
+
+	size_t nr_read;
+	b_status status = b_stream_read_char(src, &c);
+	if (!B_OK(status)) {
+		printf("read error: %s\n", b_status_description(status));
+		b_file_unref(src);
+		return -1;
+	}
+
+	b_stream_write_char(b_stdout, c);
+	b_stream_write_char(b_stdout, '\n');
+
+	b_file_unref(src);
+	return 0;
+}