From 9ffd4f7d1e11068c3cd60930e0fb0f7dc9d092b1 Mon Sep 17 00:00:00 2001
From: Rebecca Stevens <rebecca.stevens@outlook.co.nz>
Date: Sun, 9 Jan 2022 20:12:40 +1300
Subject: [PATCH] test(type-utils): add test for IndexSignature internals

---
 .../type-utils/tests/isTypeReadonly.test.ts   | 73 +++++++++++++++++--
 1 file changed, 67 insertions(+), 6 deletions(-)

diff --git a/packages/type-utils/tests/isTypeReadonly.test.ts b/packages/type-utils/tests/isTypeReadonly.test.ts
index 7153b44d7769..94e6add83372 100644
--- a/packages/type-utils/tests/isTypeReadonly.test.ts
+++ b/packages/type-utils/tests/isTypeReadonly.test.ts
@@ -176,13 +176,48 @@ describe('isTypeReadonly', () => {
 
     describe('Intersection', () => {
       describe('is readonly', () => {
-        it('handles an intersection of 2', () => {
-          const { type, checker } = getType(
-            `type Test = Readonly<{ foo: string; bar: number; }> & Readonly<{ bar: number; }>;`,
-          );
+        describe('default options', () => {
+          it('handles an intersection of 2 records', () => {
+            const { type, checker } = getType(
+              `type Test = Readonly<{ foo: string; bar: number; }> & Readonly<{ bar: number; }>;`,
+            );
 
-          const result = isTypeReadonly(checker, type);
-          expect(result).toBe(true);
+            const result = isTypeReadonly(checker, type);
+            expect(result).toBe(true);
+          });
+
+          it('handles a readonly intersection of readonly array and readonly record', () => {
+            const { type, checker } = getType(
+              `type Test = Readonly<ReadonlyArray<string> & { readonly foo: string; }>;`,
+            );
+
+            const result = isTypeReadonly(checker, type);
+            expect(result).toBe(true);
+          });
+
+          it('handles a intersection of readonly readonly array and readonly record', () => {
+            const { type, checker } = getType(
+              `type Test = Readonly<ReadonlyArray<string>> & Readonly<{ readonly foo: string; }>;`,
+            );
+
+            const result = isTypeReadonly(checker, type);
+            expect(result).toBe(true);
+          });
+        });
+
+        describe('treatMethodsAsReadonly', () => {
+          const options: ReadonlynessOptions = {
+            treatMethodsAsReadonly: true,
+          };
+
+          it('handles an intersection of readonly array and readonly record', () => {
+            const { type, checker } = getType(
+              `type Test = ReadonlyArray<string> & { readonly foo: string; };`,
+            );
+
+            const result = isTypeReadonly(checker, type, options);
+            expect(result).toBe(true);
+          });
         });
       });
 
@@ -215,5 +250,31 @@ describe('isTypeReadonly', () => {
         });
       });
     });
+
+    describe('IndexSignature', () => {
+      describe('is readonly', () => {
+        it('handles readonly PropertySignature inside a readonly IndexSignature', () => {
+          const { type, checker } = getType(
+            `type Test = { readonly [key: string]: { readonly foo: readonly string[]; }; };`,
+          );
+
+          const result = isTypeReadonly(checker, type);
+          expect(result).toBe(true);
+        });
+      });
+
+      describe('is not readonly', () => {
+        describe('default options', () => {
+          it('fails with a mutable PropertySignature inside a readonly IndexSignature', () => {
+            const { type, checker } = getType(
+              `type Test = { readonly [key: string]: { foo: string[]; }; };`,
+            );
+
+            const result = isTypeReadonly(checker, type);
+            expect(result).toBe(false);
+          });
+        });
+      });
+    });
   });
 });