Fix return type of StreamMatchers.empty & .equalTo

Return type is parameterized to yield a Matcher of the specific
Stream-type, instead of just Matcher<BaseStream<_, _>>.
See unruly/java-8-matchers#18 for more
detailed discussion.

src/main/java/uk/co/probablyfine/matchers/StreamMatchers.java

@@ -13,13 +13,13 @@
 
 public class StreamMatchers {
 
-    public static <T,S extends BaseStream<T,S>> Matcher<BaseStream<T,S>> empty() {
-        return new TypeSafeMatcher<BaseStream<T, S>>() {
+    public static <T,S extends BaseStream<T,S>> Matcher<S> empty() {
+        return new TypeSafeMatcher<S>() {
 
             private Iterator<T> actualIterator;
 
             @Override
-            protected boolean matchesSafely(BaseStream<T, S> actual) {
+            protected boolean matchesSafely(S actual) {
                 actualIterator = actual.iterator();
                 return !actualIterator.hasNext();
             }
@@ -30,7 +30,7 @@ public void describeTo(Description description) {
             }
 
             @Override
-            protected void describeMismatchSafely(BaseStream<T, S> item, Description description) {
+            protected void describeMismatchSafely(S item, Description description) {
                 description.appendText("A non empty Stream starting with ").appendValue(actualIterator.next());
             }
         };
@@ -50,10 +50,10 @@ protected void describeMismatchSafely(BaseStream<T, S> item, Description descrip
      * @see #startsWithLong
      * @see #startsWithDouble
      */
-    public static <T,S extends BaseStream<T,S>> Matcher<BaseStream<T,S>> equalTo(BaseStream<T, S> expected) {
-        return new BaseStreamMatcher<T,BaseStream<T,S>>() {
+    public static <T,S extends BaseStream<T,S>> Matcher<S> equalTo(S expected) {
+        return new BaseStreamMatcher<T,S>() {
             @Override
-            protected boolean matchesSafely(BaseStream<T,S> actual) {
+            protected boolean matchesSafely(S actual) {
                 return remainingItemsEqual(expected.iterator(), actual.iterator());
             }
         };

src/test/java/uk/co/probablyfine/matchers/StreamMatchersTest.java

@@ -4,9 +4,16 @@
 import org.hamcrest.Matchers;
 import org.junit.Test;
 
-import java.util.stream.*;
-
-import static org.hamcrest.Matchers.*;
+import java.util.stream.DoubleStream;
+import java.util.stream.IntStream;
+import java.util.stream.LongStream;
+import java.util.stream.Stream;
+
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.lessThanOrEqualTo;
+import static org.hamcrest.Matchers.not;
 import static org.junit.Assert.assertThat;
 
 public class StreamMatchersTest {
@@ -203,7 +210,7 @@ public void startsWithItemsIntStream_success() throws Exception {
 
     @Test
     public void equalTo_failureMessages() throws Exception {
-        Matcher<BaseStream<String, Stream<String>>> matcher = StreamMatchers.equalTo(Stream.of("a", "b", "c", "d", "e", "f", "g", "h"));
+        Matcher<Stream<String>> matcher = StreamMatchers.equalTo(Stream.of("a", "b", "c", "d", "e", "f", "g", "h"));
         Stream<String> testData = Stream.of("a", "b", "c", "d", "e");
         Helper.testFailingMatcher(testData, matcher, "Stream of [\"a\",\"b\",\"c\",\"d\",\"e\",\"f\",\"g\",\"h\"]", "Stream of [\"a\",\"b\",\"c\",\"d\",\"e\"]");
     }
@@ -219,7 +226,7 @@ public void contains_failureMessages() throws Exception {
     @Test
     public void equalToIntStream_failureMessages() throws Exception {
         IntStream testData = IntStream.range(8, 10);
-        Matcher<BaseStream<Integer, IntStream>> matcher = StreamMatchers.equalTo(IntStream.range(0, 6));
+        Matcher<IntStream> matcher = StreamMatchers.equalTo(IntStream.range(0, 6));
         Helper.testFailingMatcher(testData, matcher, "Stream of [<0>,<1>,<2>,<3>,<4>,<5>]", "Stream of [<8>,<9>]");
     }