Throw a custom exception if calling provided transformer throws an exception (#37)

Author: rkondratowicz

build.gradle

@@ -10,7 +10,7 @@ plugins {
 }
 
 group 'uk.gov.hmcts.reform'
-version '0.1.0'
+version '0.2.0'
 
 sourceCompatibility = 1.8
 

src/main/java/uk/gov/hmcts/reform/bulkscanccdeventhandler/handler/ExceptionRecordEventHandler.java

@@ -2,6 +2,7 @@
 
 import uk.gov.hmcts.reform.bulkscanccdeventhandler.ccd.CcdClient;
 import uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.exceptions.InvalidTransformationResultTypeException;
+import uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.exceptions.TransformationException;
 import uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.model.CaseCreationRequest;
 import uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.model.CaseCreationResult;
 import uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.validation.CaseCreationRequestValidator;
@@ -36,8 +37,19 @@ public ExceptionRecordEventHandler(
     public CaseCreationResult handle(CaseCreationRequest req) {
         validator.validate(req);
 
+        final TransformationResult result;
+        try {
+            result = transformer.transform(req.exceptionRecord);
+        } catch (Exception exc) {
+            throw new TransformationException(
+                "Provided transformer threw an exception when transforming exception record to a case. "
+                    + "See cause for details.",
+                exc
+            );
+        }
+
         return handleTransformationResult(
-            transformer.transform(req.exceptionRecord),
+            result,
             okRes -> {
                 if (okRes.warnings.isEmpty() || req.ignoreWarnings) {
                     // TODO: handle exceptions

src/main/java/uk/gov/hmcts/reform/bulkscanccdeventhandler/handler/exceptions/TransformationException.java

@@ -0,0 +1,7 @@
+package uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.exceptions;
+
+public class TransformationException extends RuntimeException {
+    public TransformationException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

src/test/java/uk/gov/hmcts/reform/bulkscanccdeventhandler/handler/ExceptionRecordEventHandlerTest.java

@@ -6,6 +6,7 @@
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import uk.gov.hmcts.reform.bulkscanccdeventhandler.ccd.CcdClient;
+import uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.exceptions.TransformationException;
 import uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.model.CaseCreationRequest;
 import uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.model.CaseCreationResult;
 import uk.gov.hmcts.reform.bulkscanccdeventhandler.handler.validation.CaseCreationRequestValidator;
@@ -15,6 +16,7 @@
 
 import static java.util.Arrays.asList;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.catchThrowable;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.never;
@@ -134,4 +136,20 @@ public void should_validate_request() {
         // then
         verify(validator).validate(req);
     }
+
+    @Test
+    void should_throw_custom_exception_when_provided_transformer_fails() {
+        // given
+        CaseCreationRequest req = SampleCaseCreationRequest.caseCreationRequest();
+        RuntimeException cause = new RuntimeException();
+        given(transformer.transform(req.exceptionRecord)).willThrow(cause);
+
+        // when
+        Throwable exc = catchThrowable(() -> handler.handle(req));
+
+        //then
+        assertThat(exc)
+            .isInstanceOf(TransformationException.class)
+            .hasCause(cause);
+    }
 }