Add CsFailureThrowable type (#27)

Signed-off-by: David Greven <[email protected]>
Signed-off-by: Sebastian Becker <[email protected]>

common-types/src/main/java/io/carbynestack/common/CsFailureThrowable.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2021 - for information on the respective copyright owner
+ * see the NOTICE file and/or the repository https://github.com/carbynestack/common.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package io.carbynestack.common;
+
+import io.carbynestack.common.result.Failure;
+
+import java.util.Optional;
+
+import static java.util.Optional.empty;
+import static java.util.Optional.ofNullable;
+
+/**
+ * Represents the Carbyne Stack throwable failure base type.
+ *
+ * @version JDK 8
+ * @see Failure
+ * @see CsFailureReason
+ * @since 0.2.0
+ */
+public interface CsFailureThrowable extends CsFailureReason {
+    /**
+     * {@inheritDoc}
+     *
+     * @return the description synopsis
+     * @see #description()
+     * @since 0.2.0
+     */
+    @Override
+    default String synopsis() {
+        return this instanceof Throwable
+                ? ((Throwable) this).getLocalizedMessage()
+                : "Throwable %s has been caught.".formatted(this);
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @return the stack trace as an {@link Optional}
+     * @since 0.2.0
+     */
+    @Override
+    default Optional<StackTraceElement[]> stackTrace() {
+        return this instanceof Throwable
+                ? ofNullable(((Throwable) this).getStackTrace())
+                : empty();
+    }
+}

common-types/src/test/java/io/carbynestack/common/CsFailureThrowableTest.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2021 - for information on the respective copyright owner
+ * see the NOTICE file and/or the repository https://github.com/carbynestack/common.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package io.carbynestack.common;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class CsFailureThrowableTest {
+    @Test
+    void throwableSynopsis() {
+        assertThat(new SomeThrowable().synopsis()).isEqualTo("Some message.");
+    }
+
+    @Test
+    void nonThrowableSynopsis() {
+        assertThat(new NonThrowable().synopsis()).isEqualTo("Throwable NonThrowable[] has been caught.");
+    }
+
+    @Test
+    void throwableStackTrace() {
+        try {
+            throw new SomeThrowable();
+        } catch (SomeThrowable throwable) {
+            assertThat(throwable.stackTrace()).isNotEmpty();
+        }
+    }
+
+    @Test
+    void nonThrowableStackTrace() {
+        assertThat(new NonThrowable().stackTrace()).isEmpty();
+    }
+
+    static final class NonThrowable implements CsFailureThrowable {
+        @Override
+        public String toString() {
+            return "NonThrowable[]";
+        }
+    }
+
+    static final class SomeThrowable extends Exception implements CsFailureThrowable {
+        @Override
+        public String getMessage() {
+            return "Some message.";
+        }
+
+        @Override
+        public String toString() {
+            return "SomeThrowable[]";
+        }
+    }
+}