Bugfix: Task#compareTo(..) implementation is not constistent to #equa…

…ls(..) implementation

build.gradle

@@ -10,7 +10,7 @@ apply plugin: 'maven-publish'
 // "incubating"
 apply plugin: 'jacoco'
 
-version = '1.0.x-SNAPSHOT'
+version = '1.0.1'
 ext.artifactGroupId = 'ch.petikoch.libs'
 ext.description = 'A little java 7+ standalone library using a "task wait for graph" model to detect deadlocks'
 

src/main/java/ch/petikoch/libs/jtwfg/Task.java

@@ -95,10 +95,16 @@ public String toString() {
 
 	@Override
 	public int compareTo(final Task<T> other) {
-		if (this.getId() instanceof Comparable && other.getId() instanceof Comparable) {
+		if ((this.getId() instanceof Comparable) &&
+				(other.getId() instanceof Comparable) &&
+				(this.getId().getClass().isAssignableFrom(other.getId().getClass()))) {
 			//noinspection unchecked
 			return ((Comparable) this.getId()).compareTo(other.getId());
 		}
-		return 0;
+		if (this.equals(other)) {
+			return 0; // "consistent" to equals
+		} else {
+			return -1; // "consistent" to equals
+		}
 	}
 }

src/test/groovy/ch/petikoch/libs/jtwfg/TaskTest.groovy

@@ -62,24 +62,34 @@ class TaskTest extends Specification {
 		result == 1
 	}
 
-	def 'compareTo: returns 0 on types not implementing comparable'() {
+	def 'compareTo: behaviour on types not implementing comparable consistent to equals'() {
 		given:
 		def taskId1 = new CustomTaskId('t1')
+		def equalTaskId1 = new CustomTaskId('t1')
 		def taskId2 = new CustomTaskId('t2')
 		def task1 = new Task<CustomTaskId>(taskId1)
+		def equalTask1 = new Task<CustomTaskId>(equalTaskId1)
 		def task2 = new Task<CustomTaskId>(taskId2)
 
 		when:
-		def result = task1.compareTo(task2)
+		def result = task1.compareTo(equalTask1)
+		then:
+		result == 0
 
+		when:
+		result = equalTask1.compareTo(task1)
 		then:
 		result == 0
 
 		when:
-		result = task2.compareTo(task1)
+		result = task1.compareTo(task2)
+		then:
+		result == -1
 
+		when:
+		result = task2.compareTo(task1)
 		then:
-		result == 0
+		result == -1
 	}
 
 	@CompileStatic