Polishing.

Add tests to verify expected behaviour of quoted expressions and string that look like expressions.
Remove comments that look like old merge conflict left overs and apply code format.

Original Pull Request: #4807

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/util/json/ParameterBindingJsonReaderUnitTests.java

@@ -15,7 +15,8 @@
  */
 package org.springframework.data.mongodb.util.json;
 
-import static org.assertj.core.api.Assertions.*;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
@@ -30,7 +31,6 @@
 import org.bson.Document;
 import org.bson.codecs.DecoderContext;
 import org.junit.jupiter.api.Test;
-
 import org.springframework.data.expression.ValueExpressionParser;
 import org.springframework.data.spel.EvaluationContextProvider;
 import org.springframework.data.spel.ExpressionDependencies;
@@ -104,6 +104,22 @@ void regexConsidersBindValueWithOptions() {
 		assertThat(pattern.getOptions()).isEqualTo("i");
 	}
 
+	@Test // GH-4806
+	void treatsQuotedValueThatLooksLikeRegexAsPlainString() {
+
+		Document target = parse("{ 'c': '/^?0$/i' }", "foo");
+
+		assertThat(target.get("c")).isInstanceOf(String.class);
+	}
+
+	@Test // GH-4806
+	void treatsStringParameterValueThatLooksLikeRegexAsPlainString() {
+
+		Document target = parse("{ 'c': ?0 }", "/^foo$/i");
+
+		assertThat(target.get("c")).isInstanceOf(String.class);
+	}
+
 	@Test
 	void bindValueToRegex() {
 
@@ -147,15 +163,13 @@ void bindToKey() {
 	@Test
 	void bindListValue() {
 
-		//
 		Document target = parse("{ 'lastname' : { $in : ?0 } }", Arrays.asList("Kohlin", "Davar"));
 		assertThat(target).isEqualTo(Document.parse("{ 'lastname' : { $in : ['Kohlin', 'Davar' ]} }"));
 	}
 
 	@Test
 	void bindListOfBinaryValue() {
 
-		//
 		byte[] value = "Kohlin".getBytes(StandardCharsets.UTF_8);
 		List<byte[]> args = Collections.singletonList(value);
 
@@ -170,28 +184,23 @@ void bindExtendedExpression() {
 		assertThat(target).isEqualTo(Document.parse("{ \"id\" : { \"$exists\" : true}}"));
 	}
 
-	// {'id':?#{ [0] ? { $exists :true} : [1] }}
-
 	@Test
 	void bindDocumentValue() {
 
-		//
 		Document target = parse("{ 'lastname' : ?0 }", new Document("$eq", "Kohlin"));
 		assertThat(target).isEqualTo(Document.parse("{ 'lastname' : { '$eq' : 'Kohlin' } }"));
 	}
 
 	@Test
 	void arrayWithoutBinding() {
 
-		//
 		Document target = parse("{ 'lastname' : { $in : [\"Kohlin\", \"Davar\"] } }");
 		assertThat(target).isEqualTo(Document.parse("{ 'lastname' : { $in : ['Kohlin', 'Davar' ]} }"));
 	}
 
 	@Test
 	void bindSpEL() {
 
-		// "{ arg0 : ?#{[0]} }"
 		Document target = parse("{ arg0 : ?#{[0]} }", 100.01D);
 		assertThat(target).isEqualTo(new Document("arg0", 100.01D));
 	}
@@ -331,9 +340,8 @@ void discoversNoDependenciesInExpression() {
 
 		String json = "{ $and : [?#{ [0] == null  ? { '$where' : 'true' } : { 'v1' : { '$in' : {[0]} } } }]}";
 
-		ExpressionDependencies expressionDependencies = new ParameterBindingDocumentCodec()
-				.captureExpressionDependencies(json, it -> new Object(),
-						ValueExpressionParser.create(SpelExpressionParser::new));
+		ExpressionDependencies expressionDependencies = new ParameterBindingDocumentCodec().captureExpressionDependencies(
+				json, it -> new Object(), ValueExpressionParser.create(SpelExpressionParser::new));
 
 		assertThat(expressionDependencies).isEqualTo(ExpressionDependencies.none());
 	}
@@ -343,9 +351,8 @@ void discoversCorrectlyDependenciesInExpression() {
 
 		String json = "{ hello: ?#{hasRole('foo')} }";
 
-		ExpressionDependencies expressionDependencies = new ParameterBindingDocumentCodec()
-				.captureExpressionDependencies(json, it -> new Object(),
-						ValueExpressionParser.create(SpelExpressionParser::new));
+		ExpressionDependencies expressionDependencies = new ParameterBindingDocumentCodec().captureExpressionDependencies(
+				json, it -> new Object(), ValueExpressionParser.create(SpelExpressionParser::new));
 
 		assertThat(expressionDependencies).isNotEmpty();
 		assertThat(expressionDependencies.get()).hasSize(1);