Create rule S8126: Custom exception classes should follow proper naming conventions

rules/S8126/apex/metadata.json

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+{
+  "title": "Custom exception classes should follow proper naming conventions",
+  "type": "CODE_SMELL",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant/Issue",
+    "constantCost": "5 min"
+  },
+  "tags": [
+    "convention",
+    "naming"
+  ],
+  "defaultSeverity": "Minor",
+  "ruleSpecification": "RSPEC-8126",
+  "sqKey": "S8126",
+  "scope": "Main",
+  "defaultQualityProfiles": [
+    "Sonar way"
+  ],
+  "quickfix": "unknown",
+  "code": {
+    "impacts": {
+      "MAINTAINABILITY": "LOW"
+    },
+    "attribute": "CONVENTIONAL"
+  }
+}

rules/S8126/apex/rule.adoc

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+This rule raises an issue when a custom exception class does not end with the suffix "Exception".
+
+== Why is this an issue?
+
+Custom exception classes serve as a way to handle specific error conditions in your Apex code. When these classes don't follow proper naming conventions, it creates several problems.
+
+First, unclear naming makes code harder to understand and maintain. A class named `MyError` or `CustomHandler` doesn't immediately signal to other developers that it's an exception class. This lack of clarity can lead to confusion when reading or debugging code.
+
+Second, Apex follows Java conventions where exception classes should end with "Exception". This convention is widely recognized and expected by developers. Breaking this convention makes your code inconsistent with established patterns.
+
+Third, proper exception naming helps with code organization and searchability. When all exception classes follow the same naming pattern, developers can quickly identify and locate them in the codebase.
+
+Finally, some development tools and static analysis systems rely on naming conventions to provide better support, such as syntax highlighting, code completion, and error detection.
+
+=== What is the potential impact?
+
+Poor naming conventions for exception classes can lead to:
+
+* Reduced code readability and maintainability
+* Confusion for team members and future developers
+* Inconsistency with Apex and Java conventions
+* Difficulty in identifying exception classes during code reviews
+* Potential issues with development tools that rely on naming patterns
+
+== How to fix it
+
+Rename your custom exception class to end with 'Exception' and ensure it properly extends the Exception class. Choose a descriptive name that clearly indicates the type of error condition it represents.
+
+=== Code examples
+
+==== Noncompliant code example
+
+[source,apex,diff-id=1,diff-type=noncompliant]
+----
+public class MyError extends Exception {} // Noncompliant
+
+public class CustomHandler extends Exception {} // Noncompliant
+
+public class ValidationIssue extends Exception {} // Noncompliant
+----
+
+==== Compliant solution
+
+[source,apex,diff-id=1,diff-type=compliant]
+----
+public class MyCustomException extends Exception {}
+
+public class CustomProcessException extends Exception {}
+
+public class ValidationException extends Exception {}
+----
+
+== Resources
+
+=== Documentation
+
+ * Apex Exception Class - https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_classes_exception_methods.htm[Official Salesforce documentation on the Exception class and its methods]
+
+ * Exception Handling in Apex - https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_exception_definition.htm[Comprehensive guide on exception handling and custom exceptions in Apex]
+
+=== Standards
+
+ * Java Naming Conventions - https://www.oracle.com/java/technologies/javase/codeconventions-namingconventions.html[Oracle's official Java naming conventions, which Apex follows for exception classes]
+
+=== Related rules
+
+ * RSPEC-2166 - https://rules.sonarsource.com/java/RSPEC-2166/[Classes named like "Exception" should extend "Exception" or a subclass (Java)]

rules/S8126/metadata.json

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+{
+}