tests/unittests: Added unit tests for sht1x

- Added unit tests for new integer only arithmetic
    - Temperature conversion differs at most 0.01°C from double arithmetic
    - Humidity conversions differs at most 0.1% from double arithmetic

tests/unittests/tests-sht1x/Makefile

@@ -0,0 +1 @@
+include $(RIOTBASE)/Makefile.base

tests/unittests/tests-sht1x/Makefile.include

@@ -0,0 +1 @@
+USEMODULE += sht1x

tests/unittests/tests-sht1x/tests-sht1x.c

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+/*
+ * Copyright (C) 2018 Otto-von-Guericke-Universität Magdeburg
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+#include <sht1x.h>
+#include <stdlib.h>
+#include "embUnit/embUnit.h"
+#include "tests-sht1x.h"
+
+/** @brief Maximum difference from correct temperature value [in e-02 °C] */
+static const int16_t max_diff_temp = 1;
+/** @brief Maximum difference from correct humidity value [in e-02 %] */
+static const int16_t max_diff_hum = 10;
+
+static int16_t expected_temp(const sht1x_dev_t *dev, uint16_t _raw)
+{
+    static const double d1_table[] = { -40.1, -39.8, -39.7, -39.6, -39.4 };
+    double d1 = d1_table[dev->vdd];
+    double d2 = (dev->conf & SHT1X_CONF_LOW_RESOLUTION) ? 0.04 : 0.01;
+    double raw = (double)_raw;
+    double temp = d1 + d2 * raw;
+
+    return (int16_t)(temp * 100.0);
+}
+
+static int16_t expected_hum(const sht1x_dev_t *dev, uint16_t _raw, int16_t _temp)
+{
+    static const double c1 = -2.0468;
+    static const double t1 = 0.01;
+    double temp = ((double)_temp) / 100.0;
+    double raw = (double)_raw;
+    double c2, c3, t2, hum_linear, hum_real;
+
+    if (dev->conf & SHT1X_CONF_LOW_RESOLUTION) {
+        c2 = 0.5872;
+        c3 = -4.0845e-04;
+        t2 = 0.00128;
+    }
+    else {
+        c2 = 0.0367;
+        c3 = -1.5955e-06;
+        t2 = 0.00008;
+    }
+
+    hum_linear = c1 + c2 * raw + c3 * (raw * raw);
+    hum_real = (temp - 25.0) * (t1 + t2 * raw) + hum_linear;
+    return (int16_t)(hum_real * 100.0);
+}
+
+static void test_sht1x_conversion(void)
+{
+    const uint8_t vdds[] = {
+        SHT1X_VDD_5_0V, SHT1X_VDD_4_0V, SHT1X_VDD_3_5V, SHT1X_VDD_3_0V,
+        SHT1X_VDD_2_5V,
+    };
+    const uint8_t confs[] = { SHT1X_CONF_LOW_RESOLUTION, 0 };
+    const uint16_t max_raw_temps[] = { 0xfff, 0x3fff };
+    const uint16_t max_raw_hums[] = { 0xff, 0xfff };
+    sht1x_dev_t dev = { .conf = 0 };
+
+    for (size_t i_res = 0; i_res < sizeof(confs) / sizeof(confs[0]); i_res++) {
+        dev.conf = confs[i_res];
+        uint16_t max_raw_temp = max_raw_temps[i_res];
+        uint16_t max_raw_hum = max_raw_hums[i_res];
+        for (size_t i_vdd = 0; i_vdd < sizeof(vdds) / sizeof(vdds[0]); i_vdd++) {
+            dev.vdd = vdds[i_vdd];
+            for (uint16_t raw_temp = 0; raw_temp <= max_raw_temp; raw_temp++) {
+                int16_t got_temp = sht1x_temperature(&dev, raw_temp);
+                int16_t exp_temp = expected_temp(&dev, raw_temp);
+
+                TEST_ASSERT(((got_temp - max_diff_temp) <= exp_temp) &&
+                            ((got_temp + max_diff_temp) >= exp_temp));
+            }
+        }
+
+        /* Testing for temperatures in -10.00°C and 65.00°C in steps of 0.13°C */
+        for (int16_t temp = -1000; temp < 6500; temp += 13) {
+            for (uint16_t raw_hum = 0; raw_hum <= max_raw_hum; raw_hum++) {
+                int16_t exp_hum = expected_hum(&dev, raw_hum, temp);
+                if ((exp_hum < 0) || (exp_hum > 10000)) {
+                    /* Result out of range, ignore it */
+                    continue;
+                }
+                int16_t got_hum = sht1x_humidity(&dev, raw_hum, temp);
+                TEST_ASSERT(((got_hum - max_diff_hum) <= exp_hum) &&
+                            ((got_hum + max_diff_hum) >= exp_hum));
+            }
+        }
+    }
+}
+
+Test *tests_sht1x_tests(void)
+{
+    EMB_UNIT_TESTFIXTURES(fixtures) {
+        new_TestFixture(test_sht1x_conversion),
+    };
+
+    EMB_UNIT_TESTCALLER(sht1x_tests, NULL, NULL, fixtures);
+
+    return (Test *)&sht1x_tests;
+}
+
+void tests_sht1x(void)
+{
+    TESTS_RUN(tests_sht1x_tests());
+}

tests/unittests/tests-sht1x/tests-sht1x.h

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+/*
+ * Copyright (C) 2018 Otto-von-Guericke-Universität Magdeburg
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @addtogroup  unittests
+ * @{
+ *
+ * @file
+ * @brief       Unittests for the conversions used in the sht1x driver
+ *
+ * @author      Marian Buschsieweke <marian.buschsieweke@ovgu.de>
+ */
+#ifndef TESTS_SHT1X_H
+#define TESTS_SHT1X_H
+
+#include "embUnit.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   The entry point of this test suite.
+ */
+void tests_sht1x(void);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* TESTS_SHT1X_H */
+/** @} */