Device side test library and test runner

tests/device/test_Print_printf/test_Print_printf.ino

@@ -0,0 +1,38 @@
+#include <BSTest.h>
+#include <StreamString.h>
+
+BS_ENV_DECLARE();
+
+void setup()
+{
+    Serial.begin(115200);
+    BS_RUN(Serial);
+}
+
+TEST_CASE("Print::printf works for any reasonable output length", "[Print]")
+{
+
+    auto test_printf = [](size_t size) {
+        StreamString str;
+        auto buf = new char[size + 1];
+        for (int i = 0; i < size; ++i) {
+            buf[i] = 'a';
+        }
+        buf[size] = 0;
+        str.printf("%s%8d", buf, 56789102);
+        delete[] buf;
+        CHECK(str.length() == size + 8);
+        CHECK(str.substring(size) == "56789102");
+    };
+
+    auto before = ESP.getFreeHeap();
+    test_printf(1);
+    test_printf(10);
+    test_printf(100);
+    test_printf(1000);
+    test_printf(10000);
+    auto after = ESP.getFreeHeap();
+    CHECK(before == after);
+}
+
+void loop() {}