feat(58): Added the 'error()' assertion and its tests

Author: rcardin

src/main/kotlin/in/rcard/assertj/arrowcore/AbstractRaiseAssert.kt

@@ -132,6 +132,11 @@ abstract class AbstractRaiseAssert<
         succeeds()
         return Assertions.assertThat((actual as RaiseResult.Success<VALUE>).value)
     }
+
+    fun error(): AbstractObjectAssert<*, ERROR> {
+        fails()
+        return Assertions.assertThat((actual as RaiseResult.Failure<ERROR>).error)
+    }
 }
 
 sealed interface RaiseResult<out ERROR : Any, out VALUE : Any> {

src/test/kotlin/in/rcard/assertj/arrowcore/RaiseAssert_error_Test.kt

@@ -0,0 +1,32 @@
+package `in`.rcard.assertj.arrowcore
+
+import `in`.rcard.assertj.arrowcore.Dummy.aFunctionThatRaisesAnError
+import `in`.rcard.assertj.arrowcore.Dummy.aFunctionThatThrowsAnException
+import `in`.rcard.assertj.arrowcore.Dummy.aFunctionWithContext
+import `in`.rcard.assertj.arrowcore.RaiseAssert.Companion.assertThat
+import `in`.rcard.assertj.arrowcore.errors.RaiseShouldFailButSucceeds.Companion.shouldFailButSucceedsWith
+import org.assertj.core.api.Assertions
+import org.junit.jupiter.api.Test
+
+internal class RaiseAssert_error_Test {
+    @Test
+    internal fun `should return a valid Object Assert if the Raise raises an error`() {
+        assertThat { aFunctionThatRaisesAnError() }.error().isEqualTo("LOGICAL ERROR")
+    }
+
+    @Test
+    internal fun `should fails if the Raise returns a value`() {
+        Assertions
+            .assertThatThrownBy { assertThat { aFunctionWithContext(42) }.error() }
+            .isInstanceOf(AssertionError::class.java)
+            .hasMessage(shouldFailButSucceedsWith(42).create())
+    }
+
+    @Test
+    internal fun `should rethrow the inner exception`() {
+        Assertions
+            .assertThatThrownBy { assertThat { aFunctionThatThrowsAnException() }.error() }
+            .isInstanceOf(RuntimeException::class.java)
+            .hasMessage("AN EXCEPTION")
+    }
+}