tests/periph/selftest_shield: Fix UART test

tests/periph/selftest_shield/main.c

@@ -55,10 +55,14 @@
 /* In order to run the periph_uart test all of the following needs to be true:
  * - periph_uart needs to be used
  * - an I/O mapping for the UART at D0/D1 needs to be provided
- * - this UART dev is not busy with stdio
+ * - this UART dev is not busy with stdio (either not using `stdio_uart` or a different UART is used for stdio)
  */
 #if defined(ARDUINO_UART_D0D1) && defined(MODULE_PERIPH_UART)
-#  define ENABLE_UART_TEST (STDIO_UART_DEV != ARDUINO_UART_D0D1)
+#  if MODULE_STDIO_UART
+#    define ENABLE_UART_TEST (STDIO_UART_DEV != ARDUINO_UART_D0D1)
+#  else
+#    define ENABLE_UART_TEST 1
+#  endif
 #  define UART_TEST_DEV ARDUINO_UART_D0D1
 #else
 #  define ENABLE_UART_TEST 0
@@ -790,6 +794,9 @@
     failed |= TEST(memcmp(testdata, serial_buf.data, sizeof(serial_buf.data)) == 0);
     failed |= TEST(serial_buf.pos == sizeof(testdata));
 
+    /* disable UART again, in case it is a shared peripheral */
+    uart_poweroff(UART_TEST_DEV);
+
     return failed;
 }
 
@@ -981,16 +988,16 @@
             if (DETAILED_OUTPUT) {
                 printf("SPI CLK %" PRIu32 " Hz\n", clk_hz);
             }
             failed |= periph_spi_rxtx_test(bus, SPI_MODE_0, clk, clk_hz, clk_check, false, "mode 0", timer_freq);
             failed |= periph_spi_rxtx_test(bus, SPI_MODE_1, clk, clk_hz, clk_check, false, "mode 1", timer_freq);
             failed |= periph_spi_rxtx_test(bus, SPI_MODE_2, clk, clk_hz, clk_check, true, "mode 2", timer_freq);
             failed |= periph_spi_rxtx_test(bus, SPI_MODE_3, clk, clk_hz, clk_check, true, "mode 3", timer_freq);
         }
     }
     return failed;
 }
 
 static bool periph_pwm_test_chan(pwm_t pwm_dev, uint8_t pwm_chan, pwm_mode_t pwm_mode, adc_t adc_line)
 {
     bool failed = false;
     print_start("PWM", "duty cycle (via ADC)");
@@ -1033,10 +1040,10 @@
 
     for (unsigned i = 0; i < ARRAY_SIZE(modes); i++) {
         if (ENABLE_PWM_TEST_D5) {
             failed |= periph_pwm_test_chan(ARDUINO_PIN_5_PWM_DEV, ARDUINO_PIN_5_PWM_CHAN, modes[i], ARDUINO_A2);
         }
         if (ENABLE_PWM_TEST_D6) {
             failed |= periph_pwm_test_chan(ARDUINO_PIN_6_PWM_DEV, ARDUINO_PIN_6_PWM_CHAN, modes[i], ARDUINO_A1);
         }
     }