Implement tokenstream_get_test and simplified assert_log_file using test names

v0/test_log.c

@@ -22,7 +22,7 @@ static void test_log_error(void) {
 
 static void test_log_on_line(void) {
     Location loc = {
-        .filename = "test.c",
+        .filename = "v0/tests/log_on_line.c2",
         .line_text = { "int main() []", 13 },
         .line = 1,
         .column_start = 12,
@@ -30,9 +30,18 @@ static void test_log_on_line(void) {
     };
 
     log_on_line(&loc, 13, "unexpected token");
-    assert_log_file("v0/tests/log_on_line.txt", "expected formatted error message");
-
-    log_clear();
-    log_on_line(&loc, 13, "unexpected token '%c'", 'x');
-    assert_log_file("v0/tests/log_on_line_variadic.txt", "expected formatted error message with variadic args");
+    assert_log_file("expected formatted error message");
+}
+
+static void test_log_on_line_variadic(void) {
+    Location loc = {
+        .filename = "v0/tests/log_on_line_variadic.c2",
+        .line_text = { "int main() []", 13 },
+        .line = 1,
+        .column_start = 12,
+        .column_end = 13
+    };
+
+    log_on_line(&loc, 13, "unexpected token '%c'", 'x');
+    assert_log_file("expected formatted error message with variadic args");
 }