feat: flat-rule-tester make sure default config always matches

lib/rule-tester/flat-rule-tester.js

@@ -84,13 +84,15 @@ const { ConfigArraySymbol } = require("@humanwhocodes/config-array");
  * testerDefaultConfig must not be modified as it allows to reset the tester to
  * the initial default configuration
  */
-const testerDefaultConfig = { rules: {} };
+const testerDefaultConfig = { files: ["**"], rules: {} };
 
 /*
  * RuleTester uses this config as its default. This can be overwritten via
  * setDefaultConfig().
+ * Files is required to also match non-JavaScript files when
+ * a test case defines a "filename".
  */
-let sharedDefaultConfig = { rules: {} };
+let sharedDefaultConfig = { ...testerDefaultConfig };
 
 /*
  * List every parameters possible on a test case that are not related to eslint
@@ -368,7 +370,10 @@ class FlatRuleTester {
         sharedDefaultConfig = config;
 
         // Make sure the rules object exists since it is assumed to exist later
-        sharedDefaultConfig.rules = sharedDefaultConfig.rules || {};
+        sharedDefaultConfig.rules = sharedDefaultConfig.rules || testerDefaultConfig.rules;
+
+        // Make sure the config is always matching if no files are specified
+        sharedDefaultConfig.files = sharedDefaultConfig.files || testerDefaultConfig.files;
     }
 
     /**
@@ -386,9 +391,7 @@ class FlatRuleTester {
      */
     static resetDefaultConfig() {
         sharedDefaultConfig = {
-            rules: {
-                ...testerDefaultConfig.rules
-            }
+            ...testerDefaultConfig
         };
     }
 

tests/lib/rule-tester/flat-rule-tester.js

@@ -124,7 +124,7 @@ describe("FlatRuleTester", () => {
             FlatRuleTester.resetDefaultConfig();
             assert.deepStrictEqual(
                 FlatRuleTester.getDefaultConfig(),
-                { rules: {} },
+                { rules: {}, files: ["**"] },
                 "The default configuration has not reset correctly"
             );
         });
@@ -1116,6 +1116,56 @@ describe("FlatRuleTester", () => {
         }());
     });
 
+    it("should allow setting the filename to a non-JavaScript file", () => {
+        ruleTester.run("", require("../../fixtures/testers/rule-tester/no-test-filename"), {
+            valid: [
+                {
+                    code: "var foo = 'bar'",
+                    filename: "somefile.ts"
+                }
+            ],
+            invalid: []
+        });
+    });
+
+    it("should allow setting the filename to a file name without extension", () => {
+        ruleTester.run("", require("../../fixtures/testers/rule-tester/no-test-filename"), {
+            valid: [
+                {
+                    code: "var foo = 'bar'",
+                    filename: "somefile"
+                }
+            ],
+            invalid: []
+        });
+    });
+
+    it("should allow setting the filename to a file path without extension", () => {
+        ruleTester.run("", require("../../fixtures/testers/rule-tester/no-test-filename"), {
+            valid: [
+                {
+                    code: "var foo = 'bar'",
+                    filename: "path/to/somefile.js"
+                }
+            ],
+            invalid: []
+        });
+    });
+
+    it("should keep allowing non-JavaScript files if the default config does not specify files", () => {
+        FlatRuleTester.setDefaultConfig({ rules: {} });
+        ruleTester.run("", require("../../fixtures/testers/rule-tester/no-test-filename"), {
+            valid: [
+                {
+                    code: "var foo = 'bar'",
+                    filename: "somefile.ts"
+                }
+            ],
+            invalid: []
+        });
+        FlatRuleTester.resetDefaultConfig();
+    });
+
     it("should pass-through the options to the rule", () => {
         ruleTester.run("no-invalid-args", require("../../fixtures/testers/rule-tester/no-invalid-args"), {
             valid: [