avoid rounding down small speed (graphhopper#2726)

Author: karussell

core/src/main/java/com/graphhopper/routing/util/VehicleTagParser.java

@@ -195,6 +195,9 @@ public final BooleanEncodedValue getAccessEnc() {
     }
 
     protected void setSpeed(boolean reverse, IntsRef edgeFlags, double speed) {
+        // special case when speed is non-zero but would be "rounded down" to 0 due to the low precision of the EncodedValue
+        if (speed > 0.1 && speed < avgSpeedEnc.getSmallestNonZeroValue())
+            speed = avgSpeedEnc.getSmallestNonZeroValue();
         if (speed < avgSpeedEnc.getSmallestNonZeroValue()) {
             avgSpeedEnc.setDecimal(reverse, edgeFlags, 0);
             accessEnc.setBool(reverse, edgeFlags, false);

core/src/test/java/com/graphhopper/routing/util/CarTagParserTest.java

@@ -360,12 +360,12 @@ public void testSetSpeed() {
     }
 
     @Test
-    public void testSetSpeed0_issue367() {
+    public void testSetSpeed0_issue367_issue1234() {
         IntsRef edgeFlags = em.createEdgeFlags();
         accessEnc.setBool(false, edgeFlags, true);
         accessEnc.setBool(true, edgeFlags, true);
 
-        parser.setSpeed(false, edgeFlags, parser.avgSpeedEnc.getSmallestNonZeroValue() - 0.01);
+        parser.setSpeed(false, edgeFlags, 0.01);
 
         // one direction effects the other direction as one encoder for speed but this is not true for access
         assertEquals(0, avSpeedEnc.getDecimal(false, edgeFlags), .1);
@@ -374,7 +374,7 @@ public void testSetSpeed0_issue367() {
         assertTrue(accessEnc.getBool(true, edgeFlags));
 
         // so always call this method with reverse=true too
-        parser.setSpeed(true, edgeFlags, parser.avgSpeedEnc.getSmallestNonZeroValue() - 0.01);
+        parser.setSpeed(true, edgeFlags, 0.01);
         assertFalse(accessEnc.getBool(true, edgeFlags));
     }