Support INTERFACE_FIELD_NO_IMPLEM (#66)

.changeset/light-ligers-jog.md

@@ -0,0 +1,5 @@
+---
+"@theguild/federation-composition": minor
+---
+
+Support INTERFACE_FIELD_NO_IMPLEM

CHANGELOG.md

@@ -4,7 +4,10 @@
 
 ### Patch Changes
 
-- [#64](https://github.com/the-guild-org/federation/pull/64) [`9ec8078`](https://github.com/the-guild-org/federation/commit/9ec80789a8e4926c04dc77d5f5b85347d5934c76) Thanks [@kamilkisiela](https://github.com/kamilkisiela)! - fix: detect incorrect subtypes of interface fields across subgraphs
+- [#64](https://github.com/the-guild-org/federation/pull/64)
+  [`9ec8078`](https://github.com/the-guild-org/federation/commit/9ec80789a8e4926c04dc77d5f5b85347d5934c76)
+  Thanks [@kamilkisiela](https://github.com/kamilkisiela)! - fix: detect incorrect subtypes of
+  interface fields across subgraphs
 
 ## 0.11.3
 

README.md

@@ -182,10 +182,10 @@ Your feedback and bug reports are welcome and appreciated.
 - ✅ `INTERFACE_OBJECT_USAGE_ERROR`
 - ✅ `REQUIRED_INACCESSIBLE`
 - ✅ `SATISFIABILITY_ERROR`
+- ✅ `INTERFACE_FIELD_NO_IMPLEM`
 
 ### TODOs
 
-- [ ] `INTERFACE_FIELD_NO_IMPLEM`
 - [ ] `DISALLOWED_INACCESSIBLE`
 - [ ] `EXTERNAL_ARGUMENT_DEFAULT_MISMATCH`
 - [ ] `EXTERNAL_ARGUMENT_TYPE_MISMATCH`

__tests__/supergraph/errors/INTERFACE_FIELD_NO_IMPLEM.spec.ts

@@ -2,7 +2,7 @@ import { expect, test } from 'vitest';
 import { graphql, testVersions } from '../../shared/testkit.js';
 
 testVersions((api, version) => {
-  test.skipIf(api.library === 'guild')('INTERFACE_FIELD_NO_IMPLEM', () => {
+  test('INTERFACE_FIELD_NO_IMPLEM (entity)', () => {
     expect(
       api.composeServices([
         {
@@ -49,7 +49,7 @@ testVersions((api, version) => {
         errors: expect.arrayContaining([
           expect.objectContaining({
             message: expect.stringContaining(
-              `Interface field "User.email" is declared in subgraph "users" but type "Author", which implements "User" only in subgraph "feed" does not have field "email".`,
+              `Interface field "User.email" is declared in subgraph "users" but type "Author", which implements "User" ${api.library === 'apollo' ? 'only ' : ''}in subgraph "feed" does not have field "email".`,
             ),
             extensions: expect.objectContaining({
               code: 'INTERFACE_FIELD_NO_IMPLEM',
@@ -58,7 +58,59 @@ testVersions((api, version) => {
         ]),
       }),
     );
+  });
+
+  test('INTERFACE_FIELD_NO_IMPLEM (data)', () => {
+    expect(
+      api.composeServices([
+        {
+          name: 'foo',
+          typeDefs: graphql`
+            type Query {
+              foo: Foo
+            }
+
+            type Foo implements Person {
+              name: String
+              age: Int
+            }
 
-    // KNOW: check all interface fields are implemented when one subgraph introduces a new field to the interface
+            interface Person {
+              name: String
+              age: Int
+            }
+          `,
+        },
+        {
+          name: 'bar',
+          typeDefs: graphql`
+            type Query {
+              bar: Bar
+            }
+
+            type Bar implements Person {
+              name: String
+            }
+
+            interface Person {
+              name: String
+            }
+          `,
+        },
+      ]),
+    ).toEqual(
+      expect.objectContaining({
+        errors: expect.arrayContaining([
+          expect.objectContaining({
+            message: expect.stringContaining(
+              `Interface field "Person.age" is declared in subgraph "foo" but type "Bar", which implements "Person" ${api.library === 'apollo' ? 'only ' : ''}in subgraph "bar" does not have field "age".`,
+            ),
+            extensions: expect.objectContaining({
+              code: 'INTERFACE_FIELD_NO_IMPLEM',
+            }),
+          }),
+        ]),
+      }),
+    );
   });
 });

src/supergraph/validation/rules/interface-field-no-implementation-rule.ts

@@ -0,0 +1,101 @@
+import { GraphQLError } from 'graphql';
+import { SupergraphVisitorMap } from '../../composition/visitor.js';
+import { SupergraphState } from '../../state.js';
+import { SupergraphValidationContext } from '../validation-context.js';
+
+export function InterfaceFieldNoImplementationRule(
+  context: SupergraphValidationContext,
+  supergraph: SupergraphState,
+): SupergraphVisitorMap {
+  return {
+    ObjectType(objectTypeState) {
+      if (objectTypeState.interfaces.size === 0) {
+        return;
+      }
+
+      for (const interfaceName of objectTypeState.interfaces) {
+        const interfaceTypeState = getTypeFromSupergraph(supergraph, interfaceName);
+
+        if (!interfaceTypeState) {
+          throw new Error(`Expected an interface to exist in supergraph state`);
+        }
+
+        if (interfaceTypeState.kind !== 'interface') {
+          throw new Error('Expected interface, got ' + interfaceTypeState.kind);
+        }
+
+        const nonRequiredFields: string[] = [];
+
+        for (const [graph, interfaceStateInGraph] of interfaceTypeState.byGraph) {
+          if (!interfaceStateInGraph.isInterfaceObject) {
+            continue;
+          }
+
+          for (const [fieldName, interfaceFieldState] of interfaceTypeState.fields) {
+            const interfaceFieldStateInGraph = interfaceFieldState.byGraph.get(graph);
+            if (!interfaceFieldStateInGraph) {
+              continue;
+            }
+
+            if (interfaceFieldStateInGraph.external) {
+              continue;
+            }
+
+            nonRequiredFields.push(fieldName);
+          }
+        }
+
+        for (const [fieldName, interfaceFieldState] of interfaceTypeState.fields) {
+          // skip fields that are defined in interface objects or in interface entities
+          if (nonRequiredFields.includes(fieldName)) {
+            continue;
+          }
+
+          // TODO: detect if a field is missing in a non-entity object type definition
+          if (objectTypeState.fields.has(fieldName) && objectTypeState.isEntity) {
+            continue;
+          }
+
+          for (const [graph, objectTypeInGraph] of objectTypeState.byGraph) {
+            // check if object in the graph, implements an interface of the same name
+            if (!objectTypeInGraph.interfaces.has(interfaceName)) {
+              // if not, continue
+              continue;
+            }
+
+            const objectFieldState = objectTypeState.fields.get(fieldName);
+
+            // if not, make sure it implements the field
+            // if (!objectFieldState?.byGraph.has(graph)) {
+            if (!objectFieldState) {
+              const interfaceFieldDefinedInGraphs = Array.from(
+                interfaceFieldState.byGraph.keys(),
+              ).map(context.graphIdToName);
+              const declaredIn =
+                interfaceFieldDefinedInGraphs.length === 1
+                  ? `subgraph "${interfaceFieldDefinedInGraphs[0]}"`
+                  : `subgraphs ${interfaceFieldDefinedInGraphs.map(g => `"${g}"`).join(', ')}`;
+
+              context.reportError(
+                new GraphQLError(
+                  `Interface field "${interfaceName}.${fieldName}" is declared in ${declaredIn} but type "${objectTypeState.name}", which implements "${interfaceName}" in subgraph "${context.graphIdToName(graph)}" does not have field "${fieldName}".`,
+                  {
+                    extensions: {
+                      code: 'INTERFACE_FIELD_NO_IMPLEM',
+                    },
+                  },
+                ),
+              );
+            }
+          }
+        }
+      }
+    },
+  };
+}
+
+function getTypeFromSupergraph(state: SupergraphState, name: string) {
+  return (
+    state.objectTypes.get(name) ?? state.interfaceTypes.get(name) ?? state.unionTypes.get(name)
+  );
+}

src/supergraph/validation/validate-supergraph.ts

@@ -26,6 +26,7 @@ import { RequiredInputFieldMissingInSomeSubgraphRule } from './rules/required-in
 import { RequiredQueryRule } from './rules/required-query-rule.js';
 import { SatisfiabilityRule } from './rules/satisfiablity-rule.js';
 import { SubgraphNameRule } from './rules/subgraph-name-rule.js';
+import { InterfaceFieldNoImplementationRule } from './rules/interface-field-no-implementation-rule.js';
 import { TypesOfTheSameKindRule } from './rules/types-of-the-same-kind-rule.js';
 import { createSupergraphValidationContext } from './validation-context.js';
 
@@ -56,6 +57,7 @@ export function validateSupergraph(
   }
 
   const postSupergraphRules = [
+    InterfaceFieldNoImplementationRule,
     ExtensionWithBaseRule,
     FieldsOfTheSameTypeRule,
     FieldArgumentsOfTheSameTypeRule,