Move static helper methods to TrisaBodyAnalyzeLib and add unit tests for them.

android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothTrisaBodyAnalyze.java

@@ -25,13 +25,13 @@ import android.support.annotation.Nullable;
 import com.health.openscale.R;
 import com.health.openscale.core.datatypes.ScaleMeasurement;
 
-import java.util.Date;
 import java.util.UUID;
 
 import timber.log.Timber;
 
-import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static com.health.openscale.core.bluetooth.lib.TrisaBodyAnalyzeLib.convertJavaTimestampToDevice;
-import static java.util.concurrent.TimeUnit.SECONDS;
+import static com.health.openscale.core.bluetooth.lib.TrisaBodyAnalyzeLib.getInt32;
+import static com.health.openscale.core.bluetooth.lib.TrisaBodyAnalyzeLib.parseScaleMeasurementData;
 
 /**
  * Driver for Trisa Body Analyze 4.0.
@@ -66,9 +66,6 @@ public class BluetoothTrisaBodyAnalyze extends BluetoothCommunication {
     private static final byte DOWNLOAD_INFORMATION_BROADCAST_ID_COMMAND = 0x21;
     private static final byte DOWNLOAD_INFORMATION_ENABLE_DISCONNECT_COMMAND = 0x22;
 
-    // Timestamp of 2010-01-01 00:00:00 UTC (or local time?)
-    private static final long TIMESTAMP_OFFSET_SECONDS = 1262304000L;
-
     /**
      * Broadcast id, which the scale will include in its Bluetooth alias. This must be set to some
      * value to complete the pairing process (though the actual value doesn't seem to matter).
@@ -250,8 +247,8 @@ public class BluetoothTrisaBodyAnalyze extends BluetoothCommunication {
         int challenge = getInt32(data, 1);
         int response = challenge ^ password;
         writeCommand(DOWNLOAD_INFORMATION_RESULT_COMMAND, response);
-        int timestamp = (int)(System.currentTimeMillis()/1000 - TIMESTAMP_OFFSET_SECONDS);
+        int deviceTimestamp = convertJavaTimestampToDevice(System.currentTimeMillis());
-        writeCommand(DOWNLOAD_INFORMATION_UTC_COMMAND, timestamp);
+        writeCommand(DOWNLOAD_INFORMATION_UTC_COMMAND, deviceTimestamp);
     }
 
     private void onScaleMeasurumentReceived(byte[] data) {
@@ -289,45 +286,6 @@ public class BluetoothTrisaBodyAnalyze extends BluetoothCommunication {
         writeBytes(WEIGHT_SCALE_SERVICE_UUID, DOWNLOAD_COMMAND_CHARACTERISTIC_UUID, bytes);
     }
 
-    @Nullable
-    private static ScaleMeasurement parseScaleMeasurementData(byte[] data) {
-        // Byte 0 contains info.
-        // Byte 1-4 contains weight.
-        // Byte 5-8 contains timestamp, if bit 0 in info byte is set.
-        // Check that we have at least weight & timestamp, which is the minimum information that
-        // ScaleMeasurement needs.
-        if (data.length < 9 || (data[0] & 1) == 0) {
-            return null;
-        }
-
-        double weight = getBase10Float(data, 1);
-        long timestamp_seconds = TIMESTAMP_OFFSET_SECONDS + (long)getInt32(data, 5);
-
-        ScaleMeasurement measurement = new ScaleMeasurement();
-        measurement.setDateTime(new Date(MILLISECONDS.convert(timestamp_seconds, SECONDS)));
-        measurement.setWeight((float)weight);
-        // TODO: calculate body composition (if possible) and set those fields too
-        return measurement;
-    }
-
-    /** Converts 4 little-endian bytes to a 32-bit integer. */
-    private static int getInt32(byte[] data, int offset) {
-        return (data[offset] & 0xff) | ((data[offset + 1] & 0xff) << 8) |
-                ((data[offset + 2] & 0xff) << 16) | ((data[offset + 3] & 0xff) << 24);
-    }
-
-    /** Converts 4 bytes to a floating point number.
-     *
-     * <p>The first three little-endian bytes form the 24-bit mantissa. The last byte contains the
-     * signed exponent, applied in base 10.
-     */
-    private static double getBase10Float(byte[] data, int offset) {
-        int mantissa = (data[offset] & 0xff) | ((data[offset + 1] & 0xff) << 8) |
-                ((data[offset + 2] & 0xff) << 16);
-        int exponent = data[offset + 3];  // note: byte is signed.
-        return mantissa * Math.pow(10, exponent);
-    }
-
     private static String getDevicePasswordKey(String deviceId) {
         return SHARED_PREFERENCES_PASSWORD_KEY_PREFIX + deviceId;
     }

android_app/app/src/main/java/com/health/openscale/core/bluetooth/lib/TrisaBodyAnalyzeLib.java

@@ -0,0 +1,92 @@
+/*  Copyright (C) 2018  Maks Verver <maks@verver.ch>
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>
+ */
+package com.health.openscale.core.bluetooth.lib;
+
+import android.support.annotation.Nullable;
+
+import com.health.openscale.core.datatypes.ScaleMeasurement;
+
+import java.time.Clock;
+import java.util.Date;
+
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.SECONDS;
+
+/**
+ * Class with static helper methods. This is a separate class for testing purposes.
+ *
+ * @see com.health.openscale.core.bluetooth.BluetoothTrisaBodyAnalyze
+ */
+public class TrisaBodyAnalyzeLib {
+
+    // Timestamp of 2010-01-01 00:00:00 UTC (or local time?)
+    private static final long TIMESTAMP_OFFSET_SECONDS = 1262304000L;
+
+    /**
+     * Converts 4 little-endian bytes to a 32-bit integer, starting from {@code offset}.
+     *
+     * @throws IndexOutOfBoundsException if {@code offset < 0} or {@code offset + 4> data.length}
+     */
+    public static int getInt32(byte[] data, int offset) {
+        return (data[offset] & 0xff) | ((data[offset + 1] & 0xff) << 8) |
+                ((data[offset + 2] & 0xff) << 16) | ((data[offset + 3] & 0xff) << 24);
+    }
+
+    /** Converts 4 bytes to a floating point number, starting from  {@code offset}.
+     *
+     * <p>The first three little-endian bytes form the 24-bit mantissa. The last byte contains the
+     * signed exponent, applied in base 10.
+     *
+     * @throws IndexOutOfBoundsException if {@code offset < 0} or {@code offset + 4> data.length}
+     */
+    public static double getBase10Float(byte[] data, int offset) {
+        int mantissa = (data[offset] & 0xff) | ((data[offset + 1] & 0xff) << 8) |
+                ((data[offset + 2] & 0xff) << 16);
+        int exponent = data[offset + 3];  // note: byte is signed.
+        return mantissa * Math.pow(10, exponent);
+    }
+
+    public static int convertJavaTimestampToDevice(long javaTimestampMillis) {
+        return (int)((javaTimestampMillis + 500)/1000 - TIMESTAMP_OFFSET_SECONDS);
+    }
+
+    public static long convertDeviceTimestampToJava(int deviceTimestampSeconds) {
+        return 1000 * (TIMESTAMP_OFFSET_SECONDS + (long)deviceTimestampSeconds);
+    }
+
+    @Nullable
+    public static ScaleMeasurement parseScaleMeasurementData(byte[] data) {
+        // Byte 0 contains info.
+        // Byte 1-4 contains weight.
+        // Byte 5-8 contains timestamp, if bit 0 in info byte is set.
+        // Check that we have at least weight & timestamp, which is the minimum information that
+        // ScaleMeasurement needs.
+        if (data.length < 9 || (data[0] & 1) == 0) {
+            return null;
+        }
+
+        double weight = getBase10Float(data, 1);
+        int deviceTimestamp = getInt32(data, 5);
+
+        ScaleMeasurement measurement = new ScaleMeasurement();
+        measurement.setDateTime(new Date(convertDeviceTimestampToJava(deviceTimestamp)));
+        measurement.setWeight((float)weight);
+        // TODO: calculate body composition (if possible) and set those fields too
+        return measurement;
+    }
+
+    private TrisaBodyAnalyzeLib() {}
+}

android_app/app/src/test/java/com/health/openscale/TrisaBodyAnalyzeLibTest.java

@@ -0,0 +1,138 @@
+package com.health.openscale;
+
+import com.health.openscale.core.datatypes.ScaleMeasurement;
+
+import junit.framework.Assert;
+
+import org.junit.Test;
+
+import java.util.Date;
+
+import static com.health.openscale.core.bluetooth.lib.TrisaBodyAnalyzeLib.convertDeviceTimestampToJava;
+import static com.health.openscale.core.bluetooth.lib.TrisaBodyAnalyzeLib.convertJavaTimestampToDevice;
+import static com.health.openscale.core.bluetooth.lib.TrisaBodyAnalyzeLib.getBase10Float;
+import static com.health.openscale.core.bluetooth.lib.TrisaBodyAnalyzeLib.getInt32;
+import static com.health.openscale.core.bluetooth.lib.TrisaBodyAnalyzeLib.parseScaleMeasurementData;
+import static junit.framework.Assert.assertEquals;
+
+/** Unit tests for {@link com.health.openscale.core.bluetooth.lib.TrisaBodyAnalyzeLib}.*/
+public class TrisaBodyAnalyzeLibTest {
+
+    @Test
+    public void getInt32Tests() {
+        byte[] data = new byte[]{1, 2, 3, 4, 5, 6};
+        assertEquals(0x04030201, getInt32(data, 0));
+        assertEquals(0x05040302, getInt32(data, 1));
+        assertEquals(0x06050403, getInt32(data, 2));
+
+        assertEquals(0xa7bdd385, getInt32(new byte[]{-123, -45, -67, -89}, 0));
+
+        assertThrows(IndexOutOfBoundsException.class, getInt32Runnable(data, -1));
+        assertThrows(IndexOutOfBoundsException.class, getInt32Runnable(data, 5));
+        assertThrows(IndexOutOfBoundsException.class, getInt32Runnable(new byte[]{1,2,3}, 0));
+    }
+
+    @Test
+    public void getBase10FloatTests() {
+        double eps = 1e-9;  // margin of error for inexact floating point comparisons
+        assertEquals(0.0, getBase10Float(new byte[]{0, 0, 0, 0}, 0));
+        assertEquals(0.0, getBase10Float(new byte[]{0, 0, 0, -1}, 0));
+        assertEquals(76.1, getBase10Float(new byte[]{-70, 29, 0, -2}, 0), eps);
+        assertEquals(1234.5678, getBase10Float(new byte[]{78, 97, -68, -4}, 0), eps);
+        assertEquals(12345678e127, getBase10Float(new byte[]{78, 97, -68, 127}, 0));
+        assertEquals(12345678e-128, getBase10Float(new byte[]{78, 97, -68, -128}, 0), eps);
+
+        byte[] data = new byte[]{1,2,3,4,5};
+        assertEquals(0x030201*1e4, getBase10Float(data, 0));
+        assertEquals(0x040302*1e5, getBase10Float(data, 1));
+
+        assertThrows(IndexOutOfBoundsException.class, getBase10FloatRunnable(data, -1));
+        assertThrows(IndexOutOfBoundsException.class, getBase10FloatRunnable(data, 5));
+        assertThrows(IndexOutOfBoundsException.class, getBase10FloatRunnable(new byte[]{1,2,3}, 0));
+    }
+
+    @Test
+    public void convertJavaTimestampToDeviceTests() {
+        assertEquals(275852082, convertJavaTimestampToDevice(1538156082000L));
+
+        // Rounds down.
+        assertEquals(275852082, convertJavaTimestampToDevice(1538156082499L));
+
+        // Rounds up.
+        assertEquals(275852083, convertJavaTimestampToDevice(1538156082500L));
+    }
+
+    @Test
+    public void convertDeviceTimestampToJavaTests() {
+        assertEquals(1538156082000L, convertDeviceTimestampToJava(275852082));
+    }
+
+    @Test
+    public void parseScaleMeasurementDataTests() {
+        long expected_timestamp_seconds = 1538156082L;  // Fri Sep 28 17:34:42 UTC 2018
+        byte[] bytes = hexToBytes("9f:ba:1d:00:fe:32:2b:71:10:00:00:00:ff:8d:14:00:ff:00:09:00");
+
+        ScaleMeasurement measurement = parseScaleMeasurementData(bytes);
+
+        assertEquals(measurement.getWeight(), 76.1f, 1e-6f);
+        assertEquals(new Date(expected_timestamp_seconds * 1000), measurement.getDateTime());
+    }
+
+    /**
+     * Creates a {@link Runnable} that will call getInt32(). In Java 8, this can be done more
+     * easily with a lambda expression at the call site, but we are using Java 7.
+     */
+    private static Runnable getInt32Runnable(final byte[] data, final int offset) {
+        return new Runnable() {
+            @Override
+            public void run() {
+                getInt32(data, offset);
+            }
+        };
+    }
+
+    /**
+     * Creates a {@link Runnable} that will call getBase10Float(). In Java 8, this can be done more
+     * easily with a lambda expression at the call site, but we are using Java 7.
+     */
+    private static Runnable getBase10FloatRunnable(final byte[] data, final int offset) {
+        return new Runnable() {
+            @Override
+            public void run() {
+                getBase10Float(data, offset);
+            }
+        };
+    }
+
+    /**
+     * Runs the given {@link Runnable} and verifies that it throws an exception of class {@code
+     * exceptionClass}. If it does, the exception will be caught and returned. If it does not (i.e.
+     * the runnable throws no exception, or throws an exception of a different class), then {@link
+     * Assert#fail} is called to abort the test.
+     */
+    private static <T extends Throwable> T assertThrows(Class<T> exceptionClass, Runnable run) {
+        try {
+            run.run();
+            Assert.fail("Expected an exception to be thrown.");
+        } catch (Throwable t) {
+            if (exceptionClass.isInstance(t)) {
+                return exceptionClass.cast(t);
+            }
+            Assert.fail("Wrong kind of exception was thrown; expected " + exceptionClass + ", received " + t.getClass());
+        }
+        return null;  // unreachable, because Assert.fail() throws an exception
+    }
+
+    /** Parses a colon-separated hex-encoded string like "aa:bb:cc:dd" into an array of bytes. */
+    private byte[] hexToBytes(String s) {
+        String[] parts = s.split(":");
+        byte[] bytes = new byte[parts.length];
+        for (int i = 0; i < bytes.length; ++i) {
+            if (parts[i].length() != 2) {
+                throw new IllegalArgumentException();
+            }
+            bytes[i] = (byte)Integer.parseInt(parts[i], 16);
+        }
+        return bytes;
+    }
+}