Hack about to fix mockito#2796

This PR contains changes NOT intended to be committed 'as-is', but as a showcase for a potential solution to:

* mockito#2796
* mockito#1593

And potentially other vararg related issues.

The crux of the issue is that Mockito needs to handle the last matcher passed to a method, when that matcher aligns with a vararg parameter and has the same type as the vararg parameter.

For example,

```java
public interface Foo {
 String m1(String... args);  // Vararg param at index 0 and type String[]
}

@test
public void shouldWork2() throws Exception  {
  // Last matcher at index 0, and with type String[]: needs special handling!
  given(foo.m1(any(String[].class))).willReturn("var arg method");
  ...
}
```

In such situations that code needs to match the raw argument, _not_ the current functionality, which is to use the last matcher to match the last _non raw_ argument.

Unfortunately, I'm not aware of a way to get at the type of the matcher without adding a method to `VarargMatcher`
to get this information. This is the downside of this approach.

src/main/java/org/mockito/ArgumentCaptor.java

@@ -62,11 +62,12 @@
 @CheckReturnValue
 public class ArgumentCaptor<T> {
 
-    private final CapturingMatcher<T> capturingMatcher = new CapturingMatcher<T>();
+    private final CapturingMatcher<T> capturingMatcher;
     private final Class<? extends T> clazz;
 
     private ArgumentCaptor(Class<? extends T> clazz) {
         this.clazz = clazz;
+        this.capturingMatcher = new CapturingMatcher<T>(clazz);
     }
 
     /**

src/main/java/org/mockito/internal/hamcrest/HamcrestArgumentMatcher.java

@@ -9,6 +9,8 @@
 import org.mockito.ArgumentMatcher;
 import org.mockito.internal.matchers.VarargMatcher;
 
+import java.util.Optional;
+
 public class HamcrestArgumentMatcher<T> implements ArgumentMatcher<T> {
 
     private final Matcher matcher;
@@ -26,6 +28,10 @@ public boolean isVarargMatcher() {
         return matcher instanceof VarargMatcher;
     }
 
+    public Optional<VarargMatcher> varargMatcher() {
+        return isVarargMatcher() ? Optional.of((VarargMatcher) matcher) : Optional.empty();
+    }
+
     @Override
     public String toString() {
         // TODO SF add unit tests and integ test coverage for toString()

src/main/java/org/mockito/internal/invocation/MatcherApplicationStrategy.java

@@ -4,12 +4,10 @@
  */
 package org.mockito.internal.invocation;
 
-import static org.mockito.internal.invocation.MatcherApplicationStrategy.MatcherApplicationType.ERROR_UNSUPPORTED_NUMBER_OF_MATCHERS;
-import static org.mockito.internal.invocation.MatcherApplicationStrategy.MatcherApplicationType.MATCH_EACH_VARARGS_WITH_LAST_MATCHER;
-import static org.mockito.internal.invocation.MatcherApplicationStrategy.MatcherApplicationType.ONE_MATCHER_PER_ARGUMENT;
-
+import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 
 import org.mockito.ArgumentMatcher;
 import org.mockito.internal.hamcrest.HamcrestArgumentMatcher;
@@ -21,21 +19,12 @@ public class MatcherApplicationStrategy {
 
     private final Invocation invocation;
     private final List<ArgumentMatcher<?>> matchers;
-    private final MatcherApplicationType matchingType;
 
     private MatcherApplicationStrategy(
             Invocation invocation,
-            List<ArgumentMatcher<?>> matchers,
-            MatcherApplicationType matchingType) {
+            List<ArgumentMatcher<?>> matchers) {
         this.invocation = invocation;
-        if (matchingType == MATCH_EACH_VARARGS_WITH_LAST_MATCHER) {
-            int times = varargLength(invocation);
-            this.matchers = appendLastMatcherNTimes(matchers, times);
-        } else {
-            this.matchers = matchers;
-        }
-
-        this.matchingType = matchingType;
+        this.matchers = matchers;
     }
 
     /**
@@ -53,8 +42,7 @@ private MatcherApplicationStrategy(
     public static MatcherApplicationStrategy getMatcherApplicationStrategyFor(
             Invocation invocation, List<ArgumentMatcher<?>> matchers) {
 
-        MatcherApplicationType type = getMatcherApplicationType(invocation, matchers);
-        return new MatcherApplicationStrategy(invocation, matchers, type);
+        return new MatcherApplicationStrategy(invocation, matchers);
     }
 
     /**
@@ -74,11 +62,35 @@ public static MatcherApplicationStrategy getMatcherApplicationStrategyFor(
      *         </ul>
      */
     public boolean forEachMatcherAndArgument(ArgumentMatcherAction action) {
-        if (matchingType == ERROR_UNSUPPORTED_NUMBER_OF_MATCHERS) {
-            return false;
+        final boolean isVararg = invocation.getMethod().isVarArgs()
+            && invocation.getRawArguments().length == matchers.size()
+            && getLastVarargMatcher(matchers).isPresent();
+
+        if (isVararg) {
+            final Type type = getLastVarargMatcher(matchers).get().type();
+            final Class<?> varArgType = invocation.getMethod().getParameterTypes()[invocation.getMethod().getParameterTypes().length - 1];
+            if (type.equals(varArgType)) {
+                return argsMatch(invocation.getRawArguments(), matchers, action);
+            }
+        }
+
+        if (invocation.getArguments().length == matchers.size()) {
+            return argsMatch(invocation.getArguments(), matchers, action);
+        }
+
+        if (isVararg) {
+            int times = varargLength(invocation);
+            final List<ArgumentMatcher<?>> matchers = appendLastMatcherNTimes(this.matchers, times);
+            return argsMatch(invocation.getArguments(), matchers, action);
         }
 
-        Object[] arguments = invocation.getArguments();
+        return false;
+    }
+
+    private boolean argsMatch(final Object[] arguments,
+                              final List<ArgumentMatcher<?>> matchers,
+                              final ArgumentMatcherAction action) {
+
         for (int i = 0; i < arguments.length; i++) {
             ArgumentMatcher<?> matcher = matchers.get(i);
             Object argument = arguments[i];
@@ -90,29 +102,12 @@ public boolean forEachMatcherAndArgument(ArgumentMatcherAction action) {
         return true;
     }
 
-    private static MatcherApplicationType getMatcherApplicationType(
-            Invocation invocation, List<ArgumentMatcher<?>> matchers) {
-        final int rawArguments = invocation.getRawArguments().length;
-        final int expandedArguments = invocation.getArguments().length;
-        final int matcherCount = matchers.size();
-
-        if (expandedArguments == matcherCount) {
-            return ONE_MATCHER_PER_ARGUMENT;
-        }
-
-        if (rawArguments == matcherCount && isLastMatcherVarargMatcher(matchers)) {
-            return MATCH_EACH_VARARGS_WITH_LAST_MATCHER;
-        }
-
-        return ERROR_UNSUPPORTED_NUMBER_OF_MATCHERS;
-    }
-
-    private static boolean isLastMatcherVarargMatcher(final List<ArgumentMatcher<?>> matchers) {
+    private static Optional<VarargMatcher> getLastVarargMatcher(final List<ArgumentMatcher<?>> matchers) {
         ArgumentMatcher<?> argumentMatcher = lastMatcher(matchers);
         if (argumentMatcher instanceof HamcrestArgumentMatcher<?>) {
-            return ((HamcrestArgumentMatcher<?>) argumentMatcher).isVarargMatcher();
+            return ((HamcrestArgumentMatcher<?>) argumentMatcher).varargMatcher();
         }
-        return argumentMatcher instanceof VarargMatcher;
+        return argumentMatcher instanceof VarargMatcher ? Optional.of((VarargMatcher) argumentMatcher) : Optional.empty();
     }
 
     private static List<ArgumentMatcher<?>> appendLastMatcherNTimes(
@@ -135,10 +130,4 @@ private static int varargLength(Invocation invocation) {
     private static ArgumentMatcher<?> lastMatcher(List<ArgumentMatcher<?>> matchers) {
         return matchers.get(matchers.size() - 1);
     }
-
-    enum MatcherApplicationType {
-        ONE_MATCHER_PER_ARGUMENT,
-        MATCH_EACH_VARARGS_WITH_LAST_MATCHER,
-        ERROR_UNSUPPORTED_NUMBER_OF_MATCHERS;
-    }
 }

src/main/java/org/mockito/internal/matchers/Any.java

@@ -5,6 +5,7 @@
 package org.mockito.internal.matchers;
 
 import java.io.Serializable;
+import java.lang.reflect.Type;
 
 import org.mockito.ArgumentMatcher;
 
@@ -21,4 +22,9 @@ public boolean matches(Object actual) {
     public String toString() {
         return "<any>";
     }
+
+    @Override
+    public Type type() {
+        return Object.class;
+    }
 }

src/main/java/org/mockito/internal/matchers/CapturingMatcher.java

@@ -7,6 +7,7 @@
 import static org.mockito.internal.exceptions.Reporter.noArgumentValueWasCaptured;
 
 import java.io.Serializable;
+import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.locks.Lock;
@@ -19,12 +20,17 @@
 public class CapturingMatcher<T>
         implements ArgumentMatcher<T>, CapturesArguments, VarargMatcher, Serializable {
 
+    private final Class<? extends T> clazz;
     private final List<Object> arguments = new ArrayList<>();
 
     private final ReadWriteLock lock = new ReentrantReadWriteLock();
     private final Lock readLock = lock.readLock();
     private final Lock writeLock = lock.writeLock();
 
+    public CapturingMatcher(final Class<? extends T> clazz) {
+        this.clazz = clazz;
+    }
+
     @Override
     public boolean matches(Object argument) {
         return true;
@@ -66,4 +72,9 @@ public void captureFrom(Object argument) {
             writeLock.unlock();
         }
     }
+
+    @Override
+    public Type type() {
+        return clazz;
+    }
 }

src/main/java/org/mockito/internal/matchers/InstanceOf.java

@@ -5,13 +5,14 @@
 package org.mockito.internal.matchers;
 
 import java.io.Serializable;
+import java.lang.reflect.Type;
 
 import org.mockito.ArgumentMatcher;
 import org.mockito.internal.util.Primitives;
 
 public class InstanceOf implements ArgumentMatcher<Object>, Serializable {
 
-    private final Class<?> clazz;
+    final Class<?> clazz;
     private final String description;
 
     public InstanceOf(Class<?> clazz) {
@@ -44,5 +45,10 @@ public VarArgAware(Class<?> clazz) {
         public VarArgAware(Class<?> clazz, String describedAs) {
             super(clazz, describedAs);
         }
+
+        @Override
+        public Type type() {
+            return clazz;
+        }
     }
 }

src/main/java/org/mockito/internal/matchers/VarargMatcher.java

@@ -5,9 +5,14 @@
 package org.mockito.internal.matchers;
 
 import java.io.Serializable;
+import java.lang.reflect.Type;
 
 /**
  * Internal interface that informs Mockito that the matcher is intended to capture varargs.
  * This information is needed when mockito collects the arguments.
  */
-public interface VarargMatcher extends Serializable {}
+public interface VarargMatcher extends Serializable {
+
+    // Todo: default impl to avoid compatability issues?
+    Type type();
+}

src/test/java/org/mockito/internal/invocation/InvocationMatcherTest.java

@@ -136,7 +136,7 @@ public void should_be_similar_if_is_overloaded_but_used_with_different_arg() thr
     public void should_capture_arguments_from_invocation() throws Exception {
         // given
         Invocation invocation = new InvocationBuilder().args("1", 100).toInvocation();
-        CapturingMatcher capturingMatcher = new CapturingMatcher();
+        CapturingMatcher capturingMatcher = new CapturingMatcher(List.class);
         InvocationMatcher invocationMatcher =
                 new InvocationMatcher(invocation, (List) asList(new Equals("1"), capturingMatcher));
 
@@ -167,7 +167,7 @@ public void should_capture_varargs_as_vararg() throws Exception {
         // given
         mock.mixedVarargs(1, "a", "b");
         Invocation invocation = getLastInvocation();
-        CapturingMatcher m = new CapturingMatcher();
+        CapturingMatcher m = new CapturingMatcher(List.class);
         InvocationMatcher invocationMatcher =
                 new InvocationMatcher(invocation, Arrays.<ArgumentMatcher>asList(new Equals(1), m));
 

src/test/java/org/mockito/internal/invocation/MatcherApplicationStrategyTest.java

@@ -12,6 +12,7 @@
 import static org.mockito.internal.invocation.MatcherApplicationStrategy.getMatcherApplicationStrategyFor;
 import static org.mockito.internal.matchers.Any.ANY;
 
+import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -230,6 +231,11 @@ public boolean matches(Object o) {
         }
 
         public void describeTo(Description description) {}
+
+        @Override
+        public Type type() {
+            return Integer.class;
+        }
     }
 
     private Invocation mixedVarargs(Object a, String... s) {

src/test/java/org/mockito/internal/matchers/CapturingMatcherTest.java

@@ -19,7 +19,7 @@ public class CapturingMatcherTest extends TestBase {
     @Test
     public void should_capture_arguments() throws Exception {
         // given
-        CapturingMatcher<String> m = new CapturingMatcher<String>();
+        CapturingMatcher<String> m = new CapturingMatcher<String>(String.class);
 
         // when
         m.captureFrom("foo");
@@ -32,7 +32,7 @@ public void should_capture_arguments() throws Exception {
     @Test
     public void should_know_last_captured_value() throws Exception {
         // given
-        CapturingMatcher<String> m = new CapturingMatcher<String>();
+        CapturingMatcher<String> m = new CapturingMatcher<String>(String.class);
 
         // when
         m.captureFrom("foo");
@@ -45,7 +45,7 @@ public void should_know_last_captured_value() throws Exception {
     @Test
     public void should_scream_when_nothing_yet_captured() throws Exception {
         // given
-        CapturingMatcher<String> m = new CapturingMatcher<String>();
+        CapturingMatcher<String> m = new CapturingMatcher<String>(String.class);
 
         try {
             // when
@@ -59,7 +59,7 @@ public void should_scream_when_nothing_yet_captured() throws Exception {
     @Test
     public void should_not_fail_when_used_in_concurrent_tests() throws Exception {
         // given
-        final CapturingMatcher<String> m = new CapturingMatcher<String>();
+        final CapturingMatcher<String> m = new CapturingMatcher<String>(String.class);
 
         // when
         m.captureFrom("concurrent access");