Generated messaging tests could create compilation errors for certain regexes in headers (#622)

* Fixed an issue with the generation of messaging tests where the regex pattern was creating compilation errors

fixes gh-620

spring-cloud-contract-verifier/src/main/groovy/org/springframework/cloud/contract/verifier/builder/JUnitMessagingMethodBodyBuilder.groovy

@@ -41,6 +41,7 @@ import static org.springframework.cloud.contract.verifier.config.TestFramework.J
  *
  * @author Marcin Grzejszczak
  * @author Jakub Kubrynski, codearte.io
+ * @author Tim Ysewyn
  *
  * @since 1.0.0
  */
@@ -244,11 +245,7 @@ class JUnitMessagingMethodBodyBuilder extends MessagingMethodBodyBuilder {
 	}
 
 	protected String createHeaderComparison(Pattern headerValue) {
-		String escapedJavaHeader = escapeJava(headerValue.toString())
+		String escapedJavaHeader = escapeJava(headerValue.pattern())
 		return "matches(\"$escapedJavaHeader\");"
 	}
-
-	private String patternText(Pattern value) {
-		return "==~ java.util.regex.Pattern.compile('$value')"
-	}
 }

spring-cloud-contract-verifier/src/main/groovy/org/springframework/cloud/contract/verifier/builder/SpockMessagingMethodBodyBuilder.groovy

@@ -30,8 +30,12 @@ import org.springframework.cloud.contract.verifier.config.ContractVerifierConfig
 import org.springframework.cloud.contract.verifier.util.MapConverter
 
 import java.util.regex.Pattern
+
+import static org.apache.commons.text.StringEscapeUtils.escapeJava
+
 /**
  * @author Jakub Kubrynski, codearte.io
+ * @author Tim Ysewyn
  */
 @PackageScope
 @TypeChecked
@@ -226,7 +230,8 @@ class SpockMessagingMethodBodyBuilder extends MessagingMethodBodyBuilder {
 	}
 
 	protected String convertHeaderComparison(Pattern headerValue) {
-		return "==~ java.util.regex.Pattern.compile('$headerValue')"
+		String converted = escapeJava(convertUnicodeEscapesIfRequired(headerValue.pattern()))
+		return "==~ java.util.regex.Pattern.compile('${converted}')"
 	}
 
 	// #273 - should escape $ for Groovy since it will try to make it a GString

spring-cloud-contract-verifier/src/test/groovy/org/springframework/cloud/contract/verifier/builder/MessagingMethodBodyBuilderSpec.groovy

@@ -824,4 +824,63 @@ Contract.make {
 			stripped(test) == stripped(expectedMsg)
 	}
 
+	@Issue('#620')
+	def "should generate tests with message headers containing regular expression which compile for [#methodBuilderName]"() {
+		given:
+			Contract contractDsl = Contract.make {
+				label 'shouldPublishMessage'
+				// input to the contract
+				input {
+					// the contract will be triggered by a method
+					triggeredBy('foo()')
+				}
+				// output message of the contract
+				outputMessage {
+					// destination to which the output message will be sent
+					sentTo('messageExchange')
+					// the body of the output message
+					body([
+							"field": "value"
+					])
+					headers {
+						header('Authorization', value(regex('Bearer [A-Za-z0-9\\-\\._~\\+\\/]+=*')))
+					}
+				}
+			}
+			MethodBodyBuilder builder = methodBuilder(contractDsl)
+			BlockBuilder blockBuilder = new BlockBuilder(" ")
+		when:
+			builder.appendTo(blockBuilder)
+			def test = blockBuilder.toString()
+		then:
+			!test.contains('cursor')
+			!test.contains('REGEXP>>')
+			test == expectedTest
+		where:
+			methodBuilderName                 | methodBuilder                                                            | expectedTest
+			"SpockMessagingMethodBodyBuilder" | { Contract dsl -> new SpockMessagingMethodBodyBuilder(dsl, properties) } | ''' when:
+  foo()
+
+ then:
+  ContractVerifierMessage response = contractVerifierMessaging.receive('messageExchange')
+  assert response != null
+  response.getHeader('Authorization')?.toString() ==~ java.util.regex.Pattern.compile('Bearer [A-Za-z0-9-._~+/]+=*')
+ and:
+  DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.payload))
+  assertThatJson(parsedJson).field("['field']").isEqualTo("value")
+'''
+			"JUnitMessagingMethodBodyBuilder" | { Contract dsl -> new JUnitMessagingMethodBodyBuilder(dsl, properties) } | ''' // when:
+  foo();
+
+ // then:
+  ContractVerifierMessage response = contractVerifierMessaging.receive("messageExchange");
+  assertThat(response).isNotNull();
+  assertThat(response.getHeader("Authorization")).isNotNull();
+  assertThat(response.getHeader("Authorization").toString()).matches("Bearer [A-Za-z0-9\\\\-\\\\._~\\\\+\\\\/]+=*");
+ // and:
+  DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload()));
+  assertThatJson(parsedJson).field("['field']").isEqualTo("value");
+'''
+	}
+
 }