inspect: Add test for circular object as result of custom inspect

src/jsutils/__tests__/inspect-test.js

@@ -86,27 +86,6 @@ describe('inspect', () => {
     expect(inspect(map)).to.equal('{ a: true, b: null }');
   });
 
-  it('detect circular objects', () => {
-    const obj = {};
-    obj.self = obj;
-    obj.deepSelf = { self: obj };
-
-    expect(inspect(obj)).to.equal(
-      '{ self: [Circular], deepSelf: { self: [Circular] } }',
-    );
-
-    const array = [];
-    array[0] = array;
-    array[1] = [array];
-
-    expect(inspect(array)).to.equal('[[Circular], [[Circular]]]');
-
-    const mixed = { array: [] };
-    mixed.array[0] = mixed;
-
-    expect(inspect(mixed)).to.equal('{ array: [[Circular]] }');
-  });
-
   it('custom inspect', () => {
     const object = {
       inspect() {
@@ -163,6 +142,37 @@ describe('inspect', () => {
     expect(inspect(object)).to.equal('Hello World!');
   });
 
+  it('detect circular objects', () => {
+    const obj = {};
+    obj.self = obj;
+    obj.deepSelf = { self: obj };
+
+    expect(inspect(obj)).to.equal(
+      '{ self: [Circular], deepSelf: { self: [Circular] } }',
+    );
+
+    const array = [];
+    array[0] = array;
+    array[1] = [array];
+
+    expect(inspect(array)).to.equal('[[Circular], [[Circular]]]');
+
+    const mixed = { array: [] };
+    mixed.array[0] = mixed;
+
+    expect(inspect(mixed)).to.equal('{ array: [[Circular]] }');
+
+    const customA = {
+      inspect: () => customB,
+    };
+
+    const customB = {
+      inspect: () => customA,
+    };
+
+    expect(inspect(customA)).to.equal('[Circular]');
+  });
+
   it('Use class names for the shortform of an object', () => {
     class Foo {
       foo: string;