(#240) Exploit generic variance to improve user experience

pom.xml

@@ -71,7 +71,7 @@
     <dependency>
       <groupId>org.cactoos</groupId>
       <artifactId>cactoos</artifactId>
-      <version>0.49</version>
+      <version>0.50</version>
     </dependency>
     <dependency>
       <groupId>org.hamcrest</groupId>

src/main/java/org/llorllale/cactoos/matchers/Assertion.java

@@ -82,7 +82,7 @@ public final class Assertion<T> {
     /**
      * Matcher.
      */
-    private final Matcher<T> matcher;
+    private final Matcher<? super T> matcher;
 
     /**
      * Ctor.
@@ -91,7 +91,7 @@ public final class Assertion<T> {
      * @param matcher Tester.
      */
     public Assertion(
-        final String msg, final T test, final Matcher<T> matcher
+        final String msg, final T test, final Matcher<? super T> matcher
     ) {
         this.msg = msg;
         this.test = test;

src/main/java/org/llorllale/cactoos/matchers/HasEntry.java

@@ -49,7 +49,7 @@
  * @param <V> Type of value.
  * @since 1.0.0
  */
-public final class HasEntry<K, V> extends MatcherEnvelope<Map<K, V>> {
+public final class HasEntry<K, V> extends MatcherEnvelope<Map<? extends K, ? extends V>> {
     /**
      * Ctor.
      * @param key The expected key.

src/main/java/org/llorllale/cactoos/matchers/HasLines.java

@@ -41,7 +41,6 @@
  *  separator.
  *
  * @since 1.0.0
- * @checkstyle ProtectedMethodInFinalClassCheck (200 lines)
  */
 public final class HasLines extends MatcherEnvelope<String> {
 
@@ -76,7 +75,7 @@ public HasLines(final Iterable<String> lns) {
      * @param lns The expected lines to be present.
      */
     public HasLines(
-        final BiFunc<Collection<String>, Collection<String>, Boolean> fnc,
+        final BiFunc<? super Collection<String>, ? super Collection<String>, Boolean> fnc,
         final Scalar<String> sep,
         final Collection<String> lns
     ) {
@@ -96,9 +95,9 @@ public HasLines(
      * @param split The function to split the text which came for testing.
      */
     private HasLines(
-        final BiFunc<Collection<String>, Collection<String>, Boolean> match,
+        final BiFunc<? super Collection<String>, ? super Collection<String>, Boolean> match,
         final Collection<String> expected,
-        final Func<String, Collection<String>> split
+        final Func<? super String, ? extends Collection<String>> split
     ) {
         super(
             new MatcherOf<>(

src/main/java/org/llorllale/cactoos/matchers/HasProperty.java

@@ -83,7 +83,7 @@ public HasProperty(final String key) {
      *
      * @param entr Entry matcher.
      */
-    private HasProperty(final Matcher<Map.Entry<String, String>> entr) {
+    private HasProperty(final Matcher<? super Map.Entry<String, String>> entr) {
         super(
             new MatcherOf<>(
                 properties -> new HasValuesMatching<>(

src/main/java/org/llorllale/cactoos/matchers/HasValue.java

@@ -36,7 +36,7 @@
  * @param <T> Type of result
  * @since 0.2
  */
-public final class HasValue<T> extends MatcherEnvelope<Scalar<T>> {
+public final class HasValue<T> extends MatcherEnvelope<Scalar<? extends T>> {
 
     /**
      * Ctor.
@@ -50,7 +50,7 @@ public HasValue(final T value) {
      * Ctor.
      * @param mtr Matcher of the value
      */
-    public HasValue(final Matcher<T> mtr) {
+    public HasValue(final Matcher<? super T> mtr) {
         super(
             new MatcherOf<>(
                 scalar -> mtr.matches(scalar.value()),

src/main/java/org/llorllale/cactoos/matchers/HasValues.java

@@ -44,7 +44,7 @@
  * @param <X> Type of item.
  * @since 1.0.0
  */
-public final class HasValues<X> extends MatcherEnvelope<Iterable<X>> {
+public final class HasValues<X> extends MatcherEnvelope<Iterable<? extends X>> {
     /**
      * Ctor.
      * @param expected The expected values within unit test.
@@ -58,7 +58,7 @@ public HasValues(final X... expected) {
      * Ctor.
      * @param expected The expected values within unit test.
      */
-    public HasValues(final Iterable<X> expected) {
+    public HasValues(final Iterable<? extends X> expected) {
         super(
             new MatcherOf<>(
                 actual -> new ListOf<>(actual).containsAll(new ListOf<>(expected)),

src/main/java/org/llorllale/cactoos/matchers/HasValuesMatching.java

@@ -45,13 +45,13 @@
  * @param <X> Type of item.
  * @since 1.0.0
  */
-public final class HasValuesMatching<X> extends MatcherEnvelope<Iterable<X>> {
+public final class HasValuesMatching<X> extends MatcherEnvelope<Iterable<? extends X>> {
     /**
      * Ctor.
      * @param fnc The function to match at least one element within the
      *  {@link Iterable}.
      */
-    public HasValuesMatching(final Func<X, Boolean> fnc) {
+    public HasValuesMatching(final Func<? super X, Boolean> fnc) {
         super(
             new MatcherOf<>(
                 actual -> new Or(fnc, actual).value(),

src/main/java/org/llorllale/cactoos/matchers/IsApplicable.java

@@ -39,7 +39,7 @@
  * @since 0.2
  */
 @SuppressWarnings("PMD.AvoidDuplicateLiterals")
-public final class IsApplicable<X, Y> extends MatcherEnvelope<Func<X, Y>> {
+public final class IsApplicable<X, Y> extends MatcherEnvelope<Func<? super X, ? extends Y>> {
 
     /**
      * Ctor.
@@ -55,7 +55,7 @@ public IsApplicable(final X inpt, final Y result) {
      * @param input Input for the function
      * @param mtr Matcher of the text
      */
-    public IsApplicable(final X input, final Matcher<Y> mtr) {
+    public IsApplicable(final X input, final Matcher<? super Y> mtr) {
         super(
             new MatcherOf<>(
                 func -> mtr.matches(

src/main/java/org/llorllale/cactoos/matchers/IsEntry.java

@@ -40,7 +40,7 @@
  * @param <V> Type of value
  * @since 1.0.0
  */
-public final class IsEntry<K, V> extends MatcherEnvelope<Map.Entry<K, V>> {
+public final class IsEntry<K, V> extends MatcherEnvelope<Map.Entry<? extends K, ? extends V>> {
 
     /**
      * Ctor.
@@ -58,7 +58,7 @@ public IsEntry(final K key, final V value) {
      * @param key Matcher for key.
      * @param value Matcher for value.
      */
-    public IsEntry(final Matcher<K> key, final Matcher<V> value) {
+    public IsEntry(final Matcher<? super K> key, final Matcher<? super V> value) {
         super(
             new MatcherOf<>(
                 entry -> new And(

src/main/java/org/llorllale/cactoos/matchers/Matches.java

@@ -48,11 +48,10 @@
  * </pre>
  *
  * @param <X> Type of item.
- * @param <M> Type of tested matcher.
  * @since 1.0.0
  * @checkstyle ProtectedMethodInFinalClassCheck (200 lines)
  */
-public final class Matches<X, M extends Matcher<X>> extends TypeSafeMatcher<M> {
+public final class Matches<X> extends TypeSafeMatcher<Matcher<? super X>> {
 
     /**
      * The testing arguments for the target matcher.
@@ -74,12 +73,12 @@ public void describeTo(final Description desc) {
     }
 
     @Override
-    protected boolean matchesSafely(final M matcher) {
+    protected boolean matchesSafely(final Matcher<? super X> matcher) {
         return matcher.matches(this.args);
     }
 
     @Override
-    protected void describeMismatchSafely(final M matcher, final Description dsc) {
+    protected void describeMismatchSafely(final Matcher<? super X> matcher, final Description dsc) {
         matcher.describeTo(dsc);
     }
 }

src/main/java/org/llorllale/cactoos/matchers/MatchesBefore.java

@@ -67,14 +67,14 @@ public final class MatchesBefore<T> extends TypeSafeDiagnosingMatcher<T> {
     /**
      * The matcher.
      */
-    private final Matcher<T> matcher;
+    private final Matcher<? super T> matcher;
 
     /**
      * Ctor.
      * @param mllsc Timeout.
      * @param mtchr Matcher.
      */
-    public MatchesBefore(final long mllsc, final Matcher<T> mtchr) {
+    public MatchesBefore(final long mllsc, final Matcher<? super T> mtchr) {
         super();
         this.millisec = mllsc;
         this.matcher = mtchr;

src/main/java/org/llorllale/cactoos/matchers/Mismatches.java

@@ -53,12 +53,11 @@
  *  }</pre>
  *
  * @param <X> Type of item.
- * @param <M> Type of tested matcher.
  * @since 1.0.0
  * @checkstyle ProtectedMethodInFinalClassCheck (200 lines)
  */
-public final class Mismatches<X, M extends Matcher<X>> extends
-    TypeSafeDiagnosingMatcher<M> {
+public final class Mismatches<X> extends
+    TypeSafeDiagnosingMatcher<Matcher<? super X>> {
 
     /**
      * Multiline start.
@@ -140,7 +139,10 @@ public void describeTo(final Description desc) {
     }
 
     @Override
-    protected boolean matchesSafely(final M matcher, final Description dsc) {
+    protected boolean matchesSafely(
+        final Matcher<? super X> matcher,
+        final Description dsc
+    ) {
         boolean mismatch;
         try {
             new Assertion<>("", this.args, matcher).affirm();

src/main/java/org/llorllale/cactoos/matchers/RunsInThreads.java

@@ -47,7 +47,7 @@
  * @since 0.24
  * @checkstyle JavadocMethodCheck (500 lines)
  */
-public final class RunsInThreads<T> extends TypeSafeDiagnosingMatcher<Func<T, Boolean>> {
+public final class RunsInThreads<T> extends TypeSafeDiagnosingMatcher<Func<? super T, Boolean>> {
 
     /**
      * Input.
@@ -88,7 +88,7 @@ public RunsInThreads(final T object, final int threads) {
 
     @Override
     public boolean matchesSafely(
-        final Func<T, Boolean> func,
+        final Func<? super T, Boolean> func,
         final Description desc
     ) {
         final ExecutorService service = Executors.newFixedThreadPool(

src/main/java/org/llorllale/cactoos/matchers/Throws.java

@@ -52,7 +52,7 @@
  * @checkstyle ProtectedMethodInFinalClassCheck (200 lines)
  */
 @SuppressWarnings("PMD.AvoidDuplicateLiterals")
-public final class Throws<T> extends TypeSafeDiagnosingMatcher<Scalar<T>> {
+public final class Throws<T> extends TypeSafeDiagnosingMatcher<Scalar<? extends T>> {
 
     /**
      * The expected exception message.
@@ -109,7 +109,7 @@ public void describeTo(final Description dsc) {
         { "PMD.AvoidCatchingGenericException", "PMD.AvoidCatchingThrowable" }
     )
     protected boolean matchesSafely(
-        final Scalar<T> obj,
+        final Scalar<? extends T> obj,
         final Description dsc
     ) {
         // @checkstyle IllegalCatchCheck (20 lines)