validation-test.ts: various grammar fixes (#3452)

Author: spawnia

src/type/__tests__/validation-test.ts

@@ -1065,7 +1065,7 @@ describe('Type System: Object fields must have output types', () => {
 });
 
 describe('Type System: Objects can only implement unique interfaces', () => {
-  it('rejects an Object implementing a non-type values', () => {
+  it('rejects an Object implementing a non-type value', () => {
     const schema = new GraphQLSchema({
       query: new GraphQLObjectType({
         name: 'BadObject',
@@ -1512,7 +1512,7 @@ describe('Type System: Arguments must have input types', () => {
     ]);
   });
 
-  it('rejects an required argument that is deprecated', () => {
+  it('rejects a required argument that is deprecated', () => {
     const schema = buildSchema(`
       directive @BadDirective(
         badArg: String! @deprecated
@@ -2610,7 +2610,7 @@ describe('Interfaces must adhere to Interface they implement', () => {
 });
 
 describe('assertValidSchema', () => {
-  it('do not throw on valid schemas', () => {
+  it('does not throw on valid schemas', () => {
     const schema = buildSchema(`
       type Query {
         foo: String
@@ -2619,7 +2619,7 @@ describe('assertValidSchema', () => {
     expect(() => assertValidSchema(schema)).to.not.throw();
   });
 
-  it('include multiple errors into a description', () => {
+  it('combines multiple errors', () => {
     const schema = buildSchema('type SomeType');
     expect(() => assertValidSchema(schema)).to.throw(dedent`
       Query root type must be provided.