Allow S to be inferred to supertype

See unruly/java-8-matchers#18 (comment)
mrwilson · Aug 1, 2020 · fe3302f · fe3302f
1 parent 2c24316
commit fe3302f
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Showing 2 changed files with 24 additions and 5 deletions.
diff --git a/src/main/java/uk/co/probablyfine/matchers/StreamMatchers.java b/src/main/java/uk/co/probablyfine/matchers/StreamMatchers.java
@@ -7,13 +7,17 @@
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
-import java.util.PrimitiveIterator;
 import java.util.Objects;
-import java.util.stream.*;
+import java.util.PrimitiveIterator;
+import java.util.stream.BaseStream;
+import java.util.stream.DoubleStream;
+import java.util.stream.IntStream;
+import java.util.stream.LongStream;
+import java.util.stream.Stream;
 
 public class StreamMatchers {
 
-    public static <T,S extends BaseStream<T,S>> Matcher<S> empty() {
+    public static <T,S extends BaseStream<T,? extends S>> Matcher<S> empty() {
         return new TypeSafeMatcher<S>() {
 
             private Iterator<T> actualIterator;
@@ -50,7 +54,7 @@ protected void describeMismatchSafely(S item, Description description) {
      * @see #startsWithLong
      * @see #startsWithDouble
      */
-    public static <T,S extends BaseStream<T,S>> Matcher<S> equalTo(S expected) {
+    public static <T,S extends BaseStream<T,? extends S>> Matcher<S> equalTo(S expected) {
         return new BaseStreamMatcher<T,S>() {
             @Override
             protected boolean matchesSafely(S actual) {
@@ -912,7 +916,7 @@ public T next() {
     private static class IntArrayIterator implements PrimitiveIterator.OfInt {
         private final int[] expected;
         private int currentPos = 0;
-        
+
         public IntArrayIterator(int... expected) {
             this.expected = expected;
         }

diff --git a/src/test/java/uk/co/probablyfine/matchers/StreamMatchersTest.java b/src/test/java/uk/co/probablyfine/matchers/StreamMatchersTest.java
@@ -3,7 +3,9 @@
 import org.hamcrest.Matcher;
 import org.hamcrest.Matchers;
 import org.junit.Test;
+import uk.co.probablyfine.matchers.function.DescribableFunction;
 
+import java.util.stream.BaseStream;
 import java.util.stream.DoubleStream;
 import java.util.stream.IntStream;
 import java.util.stream.LongStream;
@@ -15,6 +17,7 @@
 import static org.hamcrest.Matchers.lessThanOrEqualTo;
 import static org.hamcrest.Matchers.not;
 import static org.junit.Assert.assertThat;
+import static uk.co.probablyfine.matchers.Java8Matchers.where;
 
 public class StreamMatchersTest {
     @Test
@@ -215,6 +218,18 @@ public void equalTo_failureMessages() throws Exception {
         Helper.testFailingMatcher(testData, matcher, "Stream of [\"a\",\"b\",\"c\",\"d\",\"e\",\"f\",\"g\",\"h\"]", "Stream of [\"a\",\"b\",\"c\",\"d\",\"e\"]");
     }
 
+    @Test
+    public void equalTo_handles_types() {
+        Stream<Character> expectedStream = Stream.of('x', 'y', 'z');
+        assertThat("xyz", where(s -> s.chars().mapToObj(i -> (char) i), StreamMatchers.equalTo(expectedStream)));
+
+        BaseStream<Character, Stream<Character>> expectedBaseStream = Stream.of('x', 'y', 'z');
+        assertThat("xyz", where(s -> s.chars().mapToObj(i -> (char) i), StreamMatchers.equalTo(expectedBaseStream)));
+
+        DescribableFunction<String, BaseStream<Character, Stream<Character>>> characters = s -> s.chars().mapToObj(i -> (char) i);
+        assertThat("xyz", where(characters, StreamMatchers.equalTo(Stream.of('x', 'y', 'z'))));
+    }
+
 
     @Test
     public void contains_failureMessages() throws Exception {