@@ -125,10 +125,10 @@ class OverrideTester {
      */
     static and(a, b) {
         if (!b) {
-            return a;
+            return a && new OverrideTester(a.patterns, a.basePath);
         }
         if (!a) {
-            return b;
+            return new OverrideTester(b.patterns, b.basePath);
         }
 
         assert.strictEqual(a.basePath, b.basePath);
 
@@ -3592,6 +3592,36 @@ describe("CLIEngine", () => {
                 });
             });
         });
+
+        describe("with 'overrides[*].extends' setting on deep locations", () => {
+            const root = getFixturePath("cli-engine/deeply-overrides-i-extends");
+
+            it("should not throw.", () => {
+                CLIEngine = defineCLIEngineWithInMemoryFileSystem({
+                    cwd: () => root,
+                    files: {
+                        "node_modules/eslint-config-one/index.js": `module.exports = ${JSON.stringify({
+                            overrides: [{ files: ["*test*"], extends: "two" }]
+                        })}`,
+                        "node_modules/eslint-config-two/index.js": `module.exports = ${JSON.stringify({
+                            overrides: [{ files: ["*.js"], extends: "three" }]
+                        })}`,
+                        "node_modules/eslint-config-three/index.js": `module.exports = ${JSON.stringify({
+                            rules: { "no-console": "error" }
+                        })}`,
+                        "test.js": "console.log('hello')",
+                        ".eslintrc.yml": "extends: one"
+                    }
+                }).CLIEngine;
+                engine = new CLIEngine();
+
+                const { results } = engine.executeOnFiles(["test.js"]);
+                const messages = results[0].messages;
+
+                assert.strictEqual(messages.length, 1);
+                assert.strictEqual(messages[0].ruleId, "no-console");
+            });
+        });
     });
 
     describe("getConfigForFile", () => {
 
@@ -58,16 +58,22 @@ describe("OverrideTester", () => {
             assert.strictEqual(OverrideTester.and(null, null), null);
         });
 
-        it("should return the first one if the second one was null.", () => {
-            const tester = OverrideTester.create("*.js");
+        it("should return a new tester with the the first one's properties if the second one was null.", () => {
+            const tester = OverrideTester.create("*.js", null, process.cwd());
+            const result = OverrideTester.and(tester, null);
 
-            assert.strictEqual(OverrideTester.and(tester, null), tester);
+            assert.notStrictEqual(result, tester);
+            assert.strictEqual(result.patterns, tester.patterns);
+            assert.strictEqual(result.basePath, tester.basePath);
         });
 
-        it("should return the second one if the first one was null.", () => {
-            const tester = OverrideTester.create("*.js");
+        it("should return a new tester with the the second one's properties if the first one was null.", () => {
+            const tester = OverrideTester.create("*.js", null, process.cwd());
+            const result = OverrideTester.and(null, tester);
 
-            assert.strictEqual(OverrideTester.and(null, tester), tester);
+            assert.notStrictEqual(result, tester);
+            assert.strictEqual(result.patterns, tester.patterns);
+            assert.strictEqual(result.basePath, tester.basePath);
         });
 
         it("should return another one what includes both patterns if both are testers.", () => {
Original file line number	Diff line number	Diff line change
`@@ -125,10 +125,10 @@ class OverrideTester {`
`125`	`125`	`*/`
`126`	`126`	`static and(a, b) {`
`127`	`127`	`if (!b) {`
`128`		`- return a;`
	`128`	`+ return a && new OverrideTester(a.patterns, a.basePath);`
`129`	`129`	`}`
`130`	`130`	`if (!a) {`
`131`		`- return b;`
	`131`	`+ return new OverrideTester(b.patterns, b.basePath);`
`132`	`132`	`}`
`133`	`133`
`134`	`134`	`assert.strictEqual(a.basePath, b.basePath);`