add ProvidedNonNullArguments rule

README.md

@@ -103,7 +103,7 @@ Open `http://localhost:8000` in browser
     - [X] NoUnusedVariables
     - [ ] OverlappingFieldsCanBeMerged
     - [X] PossibleFragmentSpreads
-    - [ ] ProvidedNonNullArguments
+    - [X] ProvidedNonNullArguments
     - [X] ScalarLeafs
     - [X] UniqueArgumentNames
     - [X] UniqueFragmentNames

src/registry.rs

@@ -41,6 +41,14 @@ impl<'a> TypeName<'a> {
             TypeName::Named(type_name) => type_name,
         }
     }
+
+    pub fn is_non_null(&self) -> bool {
+        if let TypeName::NonNull(_) = self {
+            true
+        } else {
+            false
+        }
+    }
 }
 
 pub struct InputValue {

src/validation/mod.rs

@@ -32,7 +32,8 @@ pub fn check_rules(registry: &Registry, doc: &Document) -> Result<()> {
         .with(rules::VariablesAreInputTypes)
         .with(rules::VariableInAllowedPosition::default())
         .with(rules::ScalarLeafs)
-        .with(rules::PossibleFragmentSpreads::default());
+        .with(rules::PossibleFragmentSpreads::default())
+        .with(rules::ProvidedNonNullArguments);
 
     visit(&mut visitor, &mut ctx, doc);
     if !ctx.errors.is_empty() {

src/validation/rules/mod.rs

@@ -11,6 +11,7 @@ mod no_undefined_variables;
 mod no_unused_fragments;
 mod no_unused_variables;
 mod possible_fragment_spreads;
+mod provided_non_null_arguments;
 mod scalar_leafs;
 mod unique_argument_names;
 mod unique_fragment_names;
@@ -32,6 +33,7 @@ pub use no_undefined_variables::NoUndefinedVariables;
 pub use no_unused_fragments::NoUnusedFragments;
 pub use no_unused_variables::NoUnusedVariables;
 pub use possible_fragment_spreads::PossibleFragmentSpreads;
+pub use provided_non_null_arguments::ProvidedNonNullArguments;
 pub use scalar_leafs::ScalarLeafs;
 pub use unique_argument_names::UniqueArgumentNames;
 pub use unique_fragment_names::UniqueFragmentNames;

src/validation/rules/provided_non_null_arguments.rs

@@ -0,0 +1,54 @@
+use crate::registry::TypeName;
+use crate::validation::context::ValidatorContext;
+use crate::validation::visitor::Visitor;
+use graphql_parser::query::Field;
+use graphql_parser::schema::Directive;
+
+#[derive(Default)]
+pub struct ProvidedNonNullArguments;
+
+impl<'a> Visitor<'a> for ProvidedNonNullArguments {
+    fn enter_directive(&mut self, ctx: &mut ValidatorContext<'a>, directive: &'a Directive) {
+        if let Some(schema_directive) = ctx.registry.directives.get(&directive.name) {
+            for arg in schema_directive.args.values() {
+                if TypeName::create(&arg.ty).is_non_null() {
+                    if directive
+                        .arguments
+                        .iter()
+                        .find(|(name, _)| name == arg.name)
+                        .is_none()
+                    {
+                        ctx.report_error(vec![directive.position],
+                            format!(
+                                "Directive \"@{}\" argument \"{}\" of type \"{}\" is required but not provided",
+                                directive.name, arg.name, arg.ty
+                            ));
+                    }
+                }
+            }
+        }
+    }
+
+    fn enter_field(&mut self, ctx: &mut ValidatorContext<'a>, field: &'a Field) {
+        if let Some(parent_type) = ctx.parent_type() {
+            if let Some(schema_field) = parent_type.field_by_name(&field.name) {
+                for arg in schema_field.args.values() {
+                    if TypeName::create(&arg.ty).is_non_null() {
+                        if field
+                            .arguments
+                            .iter()
+                            .find(|(name, _)| name == arg.name)
+                            .is_none()
+                        {
+                            ctx.report_error(vec![field.position],
+                             format!(
+                                 r#"Field "{}" argument "{}" of type "{}" is required but not provided"#,
+                                 field.name, arg.name, parent_type.name()
+                             ));
+                        }
+                    }
+                }
+            }
+        }
+    }
+}