Fix some bugs with new Probability type and unit tests

src/main/java/com/gmail/nossr50/util/random/Probability.java

@@ -9,16 +9,28 @@ public interface Probability {
     /**
      * The value of this Probability
      * Should return a result between 0 and 1 (inclusive)
-     * 1 should represent something that will always succeed
-     * 0.5 should represent something that succeeds around half the time
-     * etc
+     * A value of 1 or greater represents something that will always succeed
+     * A value of around 0.5 represents something that succeeds around half the time
+     * A value of 0 represents something that will always fail
      *
      * @return the value of probability
      */
     double getValue();
 
-    static @NotNull Probability ofPercent(double percentageValue) {
-        return new ProbabilityImpl(percentageValue);
+    /**
+     * Create a new Probability with the given value
+     * A value of 100 would represent 100% chance of success
+     * A value of 50 would represent 50% chance of success
+     * A value of 0 would represent 0% chance of success
+     * A value of 1 would represent 1% chance of success
+     * A value of 0.5 would represent 0.5% chance of success
+     * A value of 0.01 would represent 0.01% chance of success
+     *
+     * @param percentage the value of the probability
+     * @return a new Probability with the given value
+     */
+    static @NotNull Probability ofPercent(double percentage) {
+        return new ProbabilityImpl(percentage);
     }
 
     /**
@@ -29,7 +41,7 @@ public interface Probability {
      * @return true for succeeding, false for failing
      */
     static private boolean isSuccessfulRoll(double probabilityValue) {
-        return (probabilityValue * 100) >= ThreadLocalRandom.current().nextDouble(100D);
+        return (probabilityValue) >= ThreadLocalRandom.current().nextDouble(1D);
     }
 
     /**

src/main/java/com/gmail/nossr50/util/random/ProbabilityImpl.java

@@ -10,14 +10,15 @@ public class ProbabilityImpl implements Probability {
     /**
      * Create a probability with a static value
      *
-     * @param staticProbability the value to assign to this probability
+     * @param percentage the percentage value of the probability
      */
-    ProbabilityImpl(double staticProbability) throws ValueOutOfBoundsException {
-        if (staticProbability < 0) {
+    ProbabilityImpl(double percentage) throws ValueOutOfBoundsException {
+        if (percentage < 0) {
             throw new ValueOutOfBoundsException("Value should never be negative for Probability! This suggests a coding mistake, contact the devs!");
         }
 
-        probabilityValue = staticProbability;
+        // Convert to a 0-1 floating point representation
+        probabilityValue = percentage / 100.0D;
     }
 
     ProbabilityImpl(double xPos, double xCeiling, double probabilityCeiling) throws ValueOutOfBoundsException {

src/test/java/com/gmail/nossr50/util/random/ProbabilityTest.java

@@ -78,7 +78,7 @@ class ProbabilityTest {
 
     @ParameterizedTest
     @MethodSource("provideProbabilitiesForWithinExpectations")
-    void testOddsExpectationsImplConstructor(Probability probability, double expectedWinPercent) {
+    void testOddsExpectationsConstructor(Probability probability, double expectedWinPercent) {
         assertExpectations(probability, expectedWinPercent);
     }