Add tests to illustrate the bug

spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistryTests.java

@@ -41,6 +41,8 @@ import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -79,6 +81,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 /**
  * @author Oleg Zhurakousky
  * @author Soby Chacko
+ * @author Chris Bono
  */
 public class SimpleFunctionRegistryTests {
 
@@ -190,6 +193,20 @@ public class SimpleFunctionRegistryTests {
 		assertThat(result).isEqualTo("{\"HELLO\":\"WORLD\"}");
 	}
 
+	// TODO: Once bug is fixed this test (last entry) will fully pass and this COMMENT should be removed
+	@ParameterizedTest
+	@ValueSource(strings = {"[hello", "hello]", "[hello]"})
+	void textContentTypeWithValueWrappedBracketsIsOk(String inputMessagePayloadValue) {
+		var catalog = new SimpleFunctionRegistry(this.conversionService, this.messageConverter, new JacksonMapper(new ObjectMapper()));
+		catalog.register(new FunctionRegistration<>(new Echo(), "echo").type(Echo.class));
+		FunctionInvocationWrapper lookedUpFunction = catalog.lookup("echo");
+		var inputMessage = MessageBuilder.withPayload(inputMessagePayloadValue)
+				.setHeader("contentType", "text/plain")
+				.build();
+		var functionResult = lookedUpFunction.apply(inputMessage);
+		assertThat(functionResult).isEqualTo(inputMessagePayloadValue);
+	}
+
 	@SuppressWarnings("unchecked")
 	@Test
 	public void testSCF762() {

spring-cloud-function-web/src/test/java/org/springframework/cloud/function/web/mvc/HttpGetIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package org.springframework.cloud.function.web.mvc;
 
 import java.net.URI;
+import java.net.URISyntaxException;
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -30,6 +31,8 @@ import java.util.stream.Collectors;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 import reactor.core.publisher.Flux;
 
 import org.springframework.beans.factory.annotation.Autowired;
@@ -56,6 +59,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Dave Syer
+ * @author Chris Bono
  */
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, properties = "spring.main.web-application-type=servlet")
 @ContextConfiguration(classes = { RestApplication.class, ApplicationConfiguration.class })
@@ -124,6 +128,18 @@ public class HttpGetIntegrationTests {
 		assertThat(result.getBody()).isEqualTo("foo");
 	}
 
+	// TODO: Once bug is fixed this test (last entry) will fully pass and this COMMENT should be removed
+	@ParameterizedTest
+	@ValueSource(strings = {"[hello", "hello]", "[hello]"})
+	void textContentTypeWithValueWrappedBracketsIsOk(String inputMessagePayloadValue) throws URISyntaxException {
+		ResponseEntity<String> postForEntity = this.rest
+				.exchange(RequestEntity.post(new URI("/echo"))
+						.contentType(MediaType.TEXT_PLAIN)
+						.body(inputMessagePayloadValue), String.class);
+		assertThat(postForEntity.getStatusCode()).isEqualTo(HttpStatus.OK);
+		assertThat(postForEntity.getBody()).isEqualTo(inputMessagePayloadValue);
+	}
+
 	@Test
 	public void foos() throws Exception {
 		ResponseEntity<String> result = this.rest
@@ -301,6 +317,11 @@ public class HttpGetIntegrationTests {
 			return () -> "foo";
 		}
 
+		@Bean
+		public Function<String, String> echo() {
+			return (input) -> input;
+		}
+
 		@Bean
 		public Supplier<Flux<Foo>> foos() {
 			return () -> Flux.just(new Foo("foo"), new Foo("bar"));