Add T.now, plus, minus methods.

app/src/main/java/info/nightscout/utils/T.java

@@ -7,6 +7,12 @@ package info.nightscout.utils;
 public class T {
     private long time; // in msec
 
+    public static T now() {
+        T t = new T();
+        t.time = System.currentTimeMillis();
+        return t;
+    }
+
     public static T msecs(long msec) {
         T t = new T();
         t.time = msec;
@@ -56,4 +62,12 @@ public class T {
     public long days() {
         return time / 24 / 60 / 60 / 1000L;
     }
+
+    public T plus(T plus) {
+        return T.msecs(time + plus.time);
+    }
+
+    public T minus(T minus) {
+        return T.msecs(time - minus.time);
+    }
 }

app/src/test/java/info/nightscout/utils/TTest.java

@@ -9,11 +9,11 @@ import org.powermock.modules.junit4.PowerMockRunner;
  * Created by mike on 26.03.2018.
  */
 
-@RunWith(PowerMockRunner.class)
+//@RunWith(PowerMockRunner.class)
 public class TTest {
 
     @Test
-    public void doTests() {
+    public void toUnits() {
         Assert.assertEquals(1, T.msecs(1000).secs());
         Assert.assertEquals(1, T.secs(60).mins());
         Assert.assertEquals(1, T.mins(60).hours());
@@ -21,4 +21,31 @@ public class TTest {
         Assert.assertEquals(24, T.days(1).hours());
         Assert.assertEquals(60000, T.mins(1).msecs());
     }
+
+    @Test
+    public void now() {
+        Assert.assertTrue(Math.abs(T.now().msecs() - System.currentTimeMillis()) < 5000);
+    }
+
+    @Test
+    public void additions() {
+        long nowMsecs = System.currentTimeMillis();
+        T now = T.msecs(nowMsecs);
+
+        Assert.assertEquals(now.plus(T.secs(5)).msecs(), nowMsecs + 5 * 1000);
+        Assert.assertEquals(now.plus(T.mins(5)).msecs(), nowMsecs + 5 * 60 * 1000);
+        Assert.assertEquals(now.plus(T.hours(5)).msecs(), nowMsecs + 5 * 60 * 60 * 1000);
+        Assert.assertEquals(now.plus(T.days(5)).msecs(), nowMsecs + 5 * 24 * 60 * 60 * 1000);
+    }
+
+    @Test
+    public void subtractions() {
+        long nowMsecs = System.currentTimeMillis();
+        T now = T.msecs(nowMsecs);
+
+        Assert.assertEquals(now.minus(T.secs(5)).msecs(), nowMsecs - 5 * 1000);
+        Assert.assertEquals(now.minus(T.mins(5)).msecs(), nowMsecs - 5 * 60 * 1000);
+        Assert.assertEquals(now.minus(T.hours(5)).msecs(), nowMsecs - 5 * 60 * 60 * 1000);
+        Assert.assertEquals(now.minus(T.days(5)).msecs(), nowMsecs - 5 * 24 * 60 * 60 * 1000);
+    }
 }