1 files changed, 47 insertions, 0 deletions
diff --git a/src/main/java/org/junit/internal/SerializableMatcherDescription.java b/src/main/java/org/junit/internal/SerializableMatcherDescription.java
new file mode 100644
index 0000000..e036557
--- /dev/null
+++ b/src/main/java/org/junit/internal/SerializableMatcherDescription.java
@@ -0,0 +1,47 @@
+package org.junit.internal;
+
+import java.io.Serializable;
+
+import org.hamcrest.BaseMatcher;
+import org.hamcrest.Description;
+import org.hamcrest.Matcher;
+import org.hamcrest.StringDescription;
+
+/**
+ * This class exists solely to provide a serializable description of a matcher to be serialized as a field in
+ * {@link AssumptionViolatedException}. Being a {@link Throwable}, it is required to be {@link Serializable}, but most
+ * implementations of {@link Matcher} are not. This class works around that limitation as
+ * {@link AssumptionViolatedException} only every uses the description of the {@link Matcher}, while still retaining
+ * backwards compatibility with classes compiled against its class signature before 4.14 and/or deserialization of
+ * previously serialized instances.
+ */
+class SerializableMatcherDescription<T> extends BaseMatcher<T> implements Serializable {
+
+    private final String matcherDescription;
+
+    private SerializableMatcherDescription(Matcher<T> matcher) {
+        matcherDescription = StringDescription.asString(matcher);
+    }
+
+    public boolean matches(Object o) {
+        throw new UnsupportedOperationException("This Matcher implementation only captures the description");
+    }
+
+    public void describeTo(Description description) {
+        description.appendText(matcherDescription);
+    }
+
+    /**
+     * Factory method that checks to see if the matcher is already serializable.
+     * @param matcher the matcher to make serializable
+     * @return The provided matcher if it is null or already serializable,
+     * the SerializableMatcherDescription representation of it if it is not.
+     */
+    static <T> Matcher<T> asSerializableMatcher(Matcher<T> matcher) {
+        if (matcher == null || matcher instanceof Serializable) {
+            return matcher;
+        } else {
+            return new SerializableMatcherDescription<T>(matcher);
+        }
+    }
+}