Option<>.collect() not to call PartialFunction collector on arguments where it is not defined (#2580)

Author: sleepytomcat

src/main/java/io/vavr/PartialFunction.java

@@ -123,7 +123,7 @@ public boolean isDefinedAt(V v) {
  * if the function is defined for the given arguments, and {@code None} otherwise.
  */
  default Function1<T, Option<R>> lift() {
- return t -> Option.when(isDefinedAt(t), apply(t));
+ return t -> Option.when(isDefinedAt(t), () -> apply(t));
  }
 
 }

src/test/java/io/vavr/control/OptionTest.java

@@ -563,6 +563,12 @@ public void shouldThrowExceptionOnNullCollectPartialFunction() {
  Option.some(1).collect(pf);
  }
 
+ @Test
+ public void shouldNotCallPartialFunctionOnUndefinedArg() {
+ final PartialFunction<Integer, Integer> pf = Function1.<Integer, Integer> of(x -> 1/x).partial(i -> i != 0);
+ assertThat(Option.of(0).collect(pf)).isEqualTo(Option.none());
+ }
+
  // -- iterator
 
  @Test