buildSchema/extendSchema: improve test coverage

src/utilities/__tests__/buildASTSchema-test.js

@@ -88,6 +88,19 @@ describe('Schema Builder', () => {
     });
   });
 
+  it('Ignores non-type system definitions', () => {
+    const sdl = `
+      type Query {
+        str: String
+      }
+
+      fragment SomeFragment on Query {
+        str
+      }
+    `;
+    expect(() => buildSchema(sdl)).to.not.throw();
+  });
+
   it('Empty type', () => {
     const sdl = dedent`
       type EmptyType
@@ -875,4 +888,27 @@ describe('Schema Builder', () => {
     buildSchema(sdl, { assumeValid: true });
     buildSchema(sdl, { assumeValidSDL: true });
   });
+
+  it('Throws on unknown types', () => {
+    const sdl = `
+      type Query {
+        unknown: UnknownType
+      }
+    `;
+    expect(() => buildSchema(sdl, { assumeValidSDL: true })).to.throw(
+      'Type "UnknownType" not found in document.',
+    );
+  });
+
+  it('Rejects invalid AST', () => {
+    // $DisableFlowOnNegativeTest
+    expect(() => buildASTSchema(null)).to.throw(
+      'Must provide valid Document AST',
+    );
+
+    // $DisableFlowOnNegativeTest
+    expect(() => buildASTSchema({})).to.throw(
+      'Must provide valid Document AST',
+    );
+  });
 });

src/utilities/__tests__/extendSchema-test.js

@@ -1158,6 +1158,32 @@ describe('extendSchema', () => {
     extendSchema(schema, extendAST, { assumeValidSDL: true });
   });
 
+  it('Throws on unknown types', () => {
+    const schema = new GraphQLSchema({});
+    const ast = parse(`
+      type Query {
+        unknown: UnknownType
+      }
+    `);
+    expect(() => extendSchema(schema, ast, { assumeValidSDL: true })).to.throw(
+      'Unknown type: "UnknownType".',
+    );
+  });
+
+  it('Rejects invalid AST', () => {
+    const schema = new GraphQLSchema({});
+
+    // $DisableFlowOnNegativeTest
+    expect(() => extendSchema(schema, null)).to.throw(
+      'Must provide valid Document AST',
+    );
+
+    // $DisableFlowOnNegativeTest
+    expect(() => extendSchema(schema, {})).to.throw(
+      'Must provide valid Document AST',
+    );
+  });
+
   it('does not allow replacing a default directive', () => {
     const schema = new GraphQLSchema({});
     const extendAST = parse(`
@@ -1231,6 +1257,20 @@ describe('extendSchema', () => {
       expect(printExtensionNodes(extendedSchema)).to.equal(extensionSDL);
     });
 
+    it('adds directive via schema extension', () => {
+      const schema = buildSchema(`
+        type Query
+
+        directive @foo on SCHEMA
+      `);
+      const extensionSDL = dedent`
+        extend schema @foo
+      `;
+      const extendedSchema = extendSchema(schema, parse(extensionSDL));
+
+      expect(printExtensionNodes(extendedSchema)).to.equal(extensionSDL);
+    });
+
     it('adds multiple new root types via schema extension', () => {
       const schema = buildSchema('type Query');
       const extendAST = parse(`

src/utilities/extendSchema.js

@@ -169,9 +169,8 @@ export function extendSchema(
     subscription:
       schemaConfig.subscription && replaceNamedType(schemaConfig.subscription),
     // Then, incorporate schema definition and all schema extensions.
-    ...astBuilder.getOperationTypes(
-      concatMaybeArrays(schemaDef && [schemaDef], schemaExtensions) || [],
-    ),
+    ...(schemaDef && astBuilder.getOperationTypes([schemaDef])),
+    ...astBuilder.getOperationTypes(schemaExtensions),
   };
 
   // Then produce and return a Schema with these types.