From af1140fac9e17fe76f561d108bbeed50ea73a5fa Mon Sep 17 00:00:00 2001
From: Yaraslau Stsetskevich <yaraslau.s@gmail.com>
Date: Fri, 15 Oct 2021 12:34:33 +0300
Subject: [PATCH 1/2] feat: introduce asNullable

---
 sanitizers/src/asNullable.ts       |  8 ++++++++
 sanitizers/src/index.ts            |  1 +
 sanitizers/test/asNullable.test.ts | 33 ++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+)
 create mode 100644 sanitizers/src/asNullable.ts
 create mode 100644 sanitizers/test/asNullable.test.ts

diff --git a/sanitizers/src/asNullable.ts b/sanitizers/src/asNullable.ts
new file mode 100644
index 0000000..e5fb687
--- /dev/null
+++ b/sanitizers/src/asNullable.ts
@@ -0,0 +1,8 @@
+import { Sanitizer, Result } from ".";
+
+export const asNullable = <T>(sanitizer: Sanitizer<T>) : Sanitizer<T | null> =>
+  (value, path) => value === null
+    ? Result.ok(null)
+      : value === undefined 
+      ? Result.error([{ path: 'path', expected: 'not undefined' }])
+        : sanitizer(value, path)
diff --git a/sanitizers/src/index.ts b/sanitizers/src/index.ts
index 7353099..b79cfd4 100644
--- a/sanitizers/src/index.ts
+++ b/sanitizers/src/index.ts
@@ -8,6 +8,7 @@ export { asFlatMapped } from './asFlatMapped'
 export { asInteger } from './asInteger'
 export { asMapped } from './asMapped'
 export { asMatching } from './asMatching'
+export { asNullable } from './asNullable'
 export { asNumber } from './asNumber'
 export { asObject } from './asObject'
 export { asOptional } from './asOptional'
diff --git a/sanitizers/test/asNullable.test.ts b/sanitizers/test/asNullable.test.ts
new file mode 100644
index 0000000..9eb57ac
--- /dev/null
+++ b/sanitizers/test/asNullable.test.ts
@@ -0,0 +1,33 @@
+import { expect } from 'chai'
+import { asString, asNullable, Result } from '../src';
+
+
+describe('asNullable', () => {
+    it('sanitizes using the nested sanitizer', async () => {
+        const asNullableString = asNullable(asString)
+        const result = asNullableString('abc', '')
+        expect(result).to.deep.equal(Result.ok('abc'))
+      })
+    
+      it('returns nested sanitizer errors', async () => {
+        const asNullableString = asNullable(asString)
+        const result = asNullableString(false, 'path')
+        expect(result).to.deep.equal(
+          Result.error([{ path: 'path', expected: 'string' }])
+        )
+      })
+    
+      it('sanitizes undefined', async () => {
+        const asNullableString = asNullable(asString)
+        const result = asNullableString(undefined, 'path')
+        expect(result).to.deep.equal(
+            Result.error([{ path: 'path', expected: 'not undefined' }])
+          )
+      })
+    
+      it('sanitizes null', async () => {
+        const asNullableString = asNullable(asString)
+        const result = asNullableString(null, 'path')
+        expect(result).to.deep.equal(Result.ok(null))
+      })
+});
\ No newline at end of file

From b2e66b408385b9cc674efdc95770bed898822f8f Mon Sep 17 00:00:00 2001
From: Dmytro Maretskyi <35851437+Marik-D@users.noreply.github.com>
Date: Fri, 15 Oct 2021 15:05:02 +0300
Subject: [PATCH 2/2] Update sanitizers/src/asNullable.ts

---
 sanitizers/src/asNullable.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sanitizers/src/asNullable.ts b/sanitizers/src/asNullable.ts
index e5fb687..59f5a1f 100644
--- a/sanitizers/src/asNullable.ts
+++ b/sanitizers/src/asNullable.ts
@@ -4,5 +4,5 @@ export const asNullable = <T>(sanitizer: Sanitizer<T>) : Sanitizer<T | null> =>
   (value, path) => value === null
     ? Result.ok(null)
       : value === undefined 
-      ? Result.error([{ path: 'path', expected: 'not undefined' }])
+      ? Result.error([{ path, expected: 'not undefined' }])
         : sanitizer(value, path)