feat: Adds UniqueDirectiveNamesRule

Author: NeedleInAJayStack

Sources/GraphQL/Validation/Rules/UniqueDirectiveNamesRule.swift

@@ -0,0 +1,40 @@
+
+/**
+ * Unique directive names
+ *
+ * A GraphQL document is only valid if all defined directives have unique names.
+ */
+func UniqueDirectiveNamesRule(
+    context: SDLValidationContext
+) -> Visitor {
+    var knownDirectiveNames = [String: Name]()
+    let schema = context.getSchema()
+
+    return Visitor(
+        enter: { node, _, _, _, _ in
+            if let node = node as? DirectiveDefinition {
+                let directiveName = node.name.value
+                if schema?.getDirective(name: directiveName) != nil {
+                    context.report(
+                        error: GraphQLError(
+                            message: "Directive \"@\(directiveName)\" already exists in the schema. It cannot be redefined.",
+                            nodes: [node.name]
+                        )
+                    )
+                    return .continue
+                }
+                if let knownName = knownDirectiveNames[directiveName] {
+                    context.report(
+                        error: GraphQLError(
+                            message: "There can be only one directive named \"@\(directiveName)\".",
+                            nodes: [knownName, node.name]
+                        )
+                    )
+                } else {
+                    knownDirectiveNames[directiveName] = node.name
+                }
+            }
+            return .continue
+        }
+    )
+}

Sources/GraphQL/Validation/SpecifiedRules.swift

@@ -43,7 +43,7 @@ public let specifiedSDLRules: [SDLValidationRule] = [
     UniqueEnumValueNamesRule,
     UniqueFieldDefinitionNamesRule,
     UniqueArgumentDefinitionNamesRule,
-//    UniqueDirectiveNamesRule,
+    UniqueDirectiveNamesRule,
     KnownTypeNamesRule,
     KnownDirectivesRule,
     UniqueDirectivesPerLocationRule,

Tests/GraphQLTests/ValidationTests/UniqueDirectiveNamesRuleTests.swift

@@ -0,0 +1,107 @@
+@testable import GraphQL
+import XCTest
+
+class UniqueDirectiveNamesRuleTests: SDLValidationTestCase {
+    override func setUp() {
+        rule = UniqueDirectiveNamesRule
+    }
+
+    func testNoDirective() throws {
+        try assertValidationErrors(
+            """
+            type Foo
+            """,
+            []
+        )
+    }
+
+    func testOneDirective() throws {
+        try assertValidationErrors(
+            """
+            directive @foo on SCHEMA
+            """,
+            []
+        )
+    }
+
+    func testManyDirectives() throws {
+        try assertValidationErrors(
+            """
+            directive @foo on SCHEMA
+            directive @bar on SCHEMA
+            directive @baz on SCHEMA
+            """,
+            []
+        )
+    }
+
+    func testDirectiveAndNonDirectiveDefinitionsNamedTheSame() throws {
+        try assertValidationErrors(
+            """
+            query foo { __typename }
+            fragment foo on foo { __typename }
+            type foo
+
+            directive @foo on SCHEMA
+            """,
+            []
+        )
+    }
+
+    func testDirectivesNamedTheSame() throws {
+        try assertValidationErrors(
+            """
+            directive @foo on SCHEMA
+
+            directive @foo on SCHEMA
+            """,
+            [
+                GraphQLError(
+                    message: #"There can be only one directive named "@foo"."#,
+                    locations: [
+                        .init(line: 1, column: 12),
+                        .init(line: 3, column: 12),
+                    ]
+                ),
+            ]
+        )
+    }
+
+    func testAddingNewDirectiveToExistingSchema() throws {
+        let schema = try buildSchema(source: "directive @foo on SCHEMA")
+        try assertValidationErrors("directive @bar on SCHEMA", schema: schema, [])
+    }
+
+    func testAddingNewDirectiveWithStandardNameToExistingSchema() throws {
+        let schema = try buildSchema(source: "type foo")
+        try assertValidationErrors(
+            "directive @skip on SCHEMA",
+            schema: schema,
+            [
+                GraphQLError(
+                    message: #"Directive "@skip" already exists in the schema. It cannot be redefined."#,
+                    locations: [.init(line: 1, column: 12)]
+                ),
+            ]
+        )
+    }
+
+    func testAddingNewDirectiveToExistingSchemaWithSameNamedType() throws {
+        let schema = try buildSchema(source: "type foo")
+        try assertValidationErrors("directive @foo on SCHEMA", schema: schema, [])
+    }
+
+    func testAddingConflictingDirectiveToExistingSchema() throws {
+        let schema = try buildSchema(source: "directive @foo on SCHEMA")
+        try assertValidationErrors(
+            "directive @foo on SCHEMA",
+            schema: schema,
+            [
+                GraphQLError(
+                    message: #"Directive "@foo" already exists in the schema. It cannot be redefined."#,
+                    locations: [.init(line: 1, column: 12)]
+                ),
+            ]
+        )
+    }
+}