test(linter): add rule configuration consistency test

AGENTS.md

@@ -31,7 +31,6 @@ Start from the `crates/` directory when exploring the codebase.
 
 Sub-directories named `generated` are code generated, do not edit files in these directories.
 
-
 ### Important Crates Overview
 
 - **`oxc_parser`** - JavaScript/TypeScript parser

crates/oxc_linter/tests/rule_configuration_test.rs

@@ -0,0 +1,85 @@
+//! Test to ensure rule configuration consistency
+//!
+//! This test verifies that for all linter rules, the default configuration
+//! obtained via `Default::default()` matches the configuration obtained via
+//! `from_configuration(null)`. This helps prevent bugs where rules behave
+//! differently depending on how they are initialized.
+
+use oxc_linter::rules::RULES;
+use serde_json::Value;
+
+/// Test to ensure consistency between `rule::default()` and `rule::from_configuration(null)`.
+///
+/// This test helps prevent issues where a rule's default configuration differs from
+/// its configuration when initialized with a null value. Both should produce identical
+/// results to maintain consistency in rule behavior.
+///
+/// See issue #12718 for an example of why this test is important.
+#[test]
+fn test_rule_default_matches_from_configuration_null() {
+    let mut failures = Vec::new();
+
+    // Rules that are known to have configuration mismatches and need to be fixed
+    // TODO: These should be removed as the rules are fixed to have consistent defaults
+    // When fixing a rule, ensure that either:
+    // 1. The Default implementation returns the same values as from_configuration(null), or
+    // 2. The from_configuration method is updated to return Default::default() when given null
+    let exceptions = [
+        "eslint/new-cap",
+        "eslint/no-unneeded-ternary",
+        "eslint/no-else-return",
+        "import/extensions",
+        "import/no-anonymous-default-export",
+        "jest/no-deprecated-functions",
+        "jest/no-large-snapshots",
+        "jest/prefer-lowercase-title",
+        "react/jsx-filename-extension",
+        "typescript/no-this-alias",
+        "unicorn/prefer-object-from-entries",
+        "unicorn/prefer-structured-clone",
+    ];
+
+    // Iterate through all available linter rules
+    for rule in RULES.iter() {
+        let plugin_name = rule.plugin_name();
+        let rule_name = rule.name();
+
+        // Skip rules that are known to have issues
+        if exceptions.contains(&format!("{plugin_name}/{rule_name}").as_str()) {
+            continue;
+        }
+
+        // Get the default configuration using rule::default
+        let default_rule = rule.clone();
+
+        // Get the configuration using rule::from_configuration(null)
+        let null_configured_rule = rule.read_json(Value::Null);
+
+        // Compare the two configurations
+        // Since RuleEnum doesn't implement PartialEq for the inner rule types,
+        // we need to compare them by running them and checking their behavior
+        // For now, we'll use the debug representation as a proxy
+        let default_debug = format!("{default_rule:?}");
+        let null_debug = format!("{null_configured_rule:?}");
+
+        if default_debug != null_debug {
+            failures.push(format!(
+                "Rule '{plugin_name}/{rule_name}' has different configurations between default() and from_configuration(null).\n\
+                 Default: {default_debug}\n\
+                 From null: {null_debug}",
+
+            ));
+        }
+    }
+
+    assert!(
+        failures.is_empty(),
+        "Found {} rules with configuration mismatches:\n\n{}\n\n\
+To fix these issues:\n\
+1. Update the Default implementation to match from_configuration(null), or\n\
+2. Update from_configuration to return Default::default() when given null\n\
+3. Add the rule to the exceptions list above if the mismatch is intentional",
+        failures.len(),
+        failures.join("\n\n")
+    );
+}