SONARPY-994 S5361 should not create false positives when case-insensitive flag is set (#1111)

Author: nils-werner-sonarsource

python-checks/src/main/java/org/sonar/python/checks/regex/StringReplaceCheck.java

@@ -21,6 +21,7 @@
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.regex.Pattern;
 import org.sonar.check.Rule;
 import org.sonar.plugins.python.api.tree.CallExpression;
 import org.sonar.python.regex.PythonRegexIssueLocation;
@@ -44,7 +45,11 @@ protected Map<String, Integer> lookedUpFunctions() {
   @Override
   public void checkRegex(RegexParseResult regexParseResult, CallExpression callExpression) {
     RegexTree regex = regexParseResult.getResult();
-    if (!regexParseResult.hasSyntaxErrors() && isPlainString(regex)) {
+    if (regexParseResult.hasSyntaxErrors() || regex.activeFlags().contains(Pattern.CASE_INSENSITIVE)) {
+      return;
+    }
+
+    if (isPlainString(regex)) {
       regexContext.addIssue(callExpression.callee(), MESSAGE)
         .secondary(PythonRegexIssueLocation.preciseLocation(regex, SECONDARY_MESSAGE));
     }

python-checks/src/test/resources/checks/regex/stringReplaceCheck.py

@@ -36,7 +36,8 @@ def compliant():
     changed = re.sub(r"x+", "It's", input)
     changed = re.sub(r"[\\]", "It's", input)
     changed = re.sub(r"", "It's", input)
-    changed = re.match(r"Bob is", input)
+    changed = re.sub(r"Bob is", "It's", input, flags=re.IGNORECASE)
+    changed = re.sub(r"Bob is", "It's", input, 1, re.IGNORECASE)
 
 def coverage(input):
     re.match(r"Bob is", input)