Cleanup and documentation

Author: NeedleInAJayStack

Sources/GraphQL/Utilities/ValueFromAST.swift

@@ -68,15 +68,15 @@ func valueFromAST(valueAST: Value, type: GraphQLInputType, variables: [String: M
         return try .dictionary(fields.keys.reduce(OrderedDictionary<String, Map>()) { obj, fieldName in
             var obj = obj
             let field = fields[fieldName]!
-            let fieldAST = fieldASTs[fieldName]
-            if let fieldAST = fieldAST {
+            if let fieldAST = fieldASTs[fieldName] {
                 let fieldValue = try valueFromAST(
                     valueAST: fieldAST.value,
                     type: field.type,
                     variables: variables
                 )
                 obj[fieldName] = fieldValue
             } else {
+                // If AST doesn't contain field, it is undefined
                 if let defaultValue = field.defaultValue {
                     obj[fieldName] = defaultValue
                 } else {
@@ -92,7 +92,6 @@ func valueFromAST(valueAST: Value, type: GraphQLInputType, variables: [String: M
         throw GraphQLError(message: "Must be leaf type")
     }
 
-    let parsed = try type.parseLiteral(valueAST: valueAST)
-    
-    return parsed
+    // If we've made it this far, it should be a literal
+    return try type.parseLiteral(valueAST: valueAST)
 }

Tests/GraphQLTests/InputTests/InputTests.swift

@@ -5,6 +5,7 @@ import NIO
 
 class InputTests : XCTestCase {
 
+    // Test that input objects parse as expected from non-null literals
     func testInputParsing() throws {
         struct Echo : Codable {
             let field1: String?
@@ -110,6 +111,7 @@ class InputTests : XCTestCase {
         )
     }
 
+    // Test that inputs parse as expected when null literals are present
     func testInputParsingDefinedNull() throws {
         struct Echo : Codable {
             let field1: String?
@@ -215,6 +217,7 @@ class InputTests : XCTestCase {
         )
     }
 
+    // Test that input objects parse as expected when there are missing fields with no default
     func testInputParsingUndefined() throws {
         struct Echo : Codable {
             let field1: String?
@@ -319,6 +322,7 @@ class InputTests : XCTestCase {
         )
     }
 
+    // Test that input objects parse as expected when there are missing fields with defaults
     func testInputParsingUndefinedWithDefault() throws {
         struct Echo : Codable {
             let field1: String?