From 30d6a0a58dcdd20bf9ef555d5fc476436f520f85 Mon Sep 17 00:00:00 2001
From: Dmitrii Skurikhin <dmitrii.sk@gmail.com>
Date: Tue, 31 Mar 2020 10:04:34 +0300
Subject: [PATCH] encode null value as "null"

---
 CHANGELOG.md                              | 3 +++
 src/Language/GraphQL/AST/Encoder.hs       | 2 +-
 tests/Language/GraphQL/AST/EncoderSpec.hs | 5 +++++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52b95ad..5a250a4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,9 @@ and this project adheres to
 [Haskell Package Versioning Policy](https://pvp.haskell.org/).
 
 ## [Unreleased]
+### Fixed
+- Result of null encoding
+
 ### Added
 - AST for the GraphQL schema.
 - Type system definition parser.
diff --git a/src/Language/GraphQL/AST/Encoder.hs b/src/Language/GraphQL/AST/Encoder.hs
index 9b293bf..f5bfcc3 100644
--- a/src/Language/GraphQL/AST/Encoder.hs
+++ b/src/Language/GraphQL/AST/Encoder.hs
@@ -205,7 +205,7 @@ value _ (Full.Variable x) = variable x
 value _ (Full.Int x) = Builder.toLazyText $ decimal x
 value _ (Full.Float x) = Builder.toLazyText $ realFloat x
 value _ (Full.Boolean  x) = booleanValue x
-value _ Full.Null = mempty
+value _ Full.Null = "null"
 value formatter (Full.String string) = stringValue formatter string
 value _ (Full.Enum x) = Lazy.Text.fromStrict x
 value formatter (Full.List x) = listValue formatter x
diff --git a/tests/Language/GraphQL/AST/EncoderSpec.hs b/tests/Language/GraphQL/AST/EncoderSpec.hs
index 00a875c..6aa8192 100644
--- a/tests/Language/GraphQL/AST/EncoderSpec.hs
+++ b/tests/Language/GraphQL/AST/EncoderSpec.hs
@@ -12,6 +12,11 @@ import Text.RawString.QQ (r)
 spec :: Spec
 spec = do
     describe "value" $ do
+        context "null value" $ do
+            let testNull formatter = value formatter Null `shouldBe` "null"
+            it "minified" $ testNull minified
+            it "pretty" $ testNull pretty
+
         context "minified" $ do
             it "escapes \\" $
                 value minified (String "\\") `shouldBe` "\"\\\\\""