diff --git a/src/validation/__tests__/FieldsOnCorrectTypeRule-test.ts b/src/validation/__tests__/FieldsOnCorrectTypeRule-test.ts
index 6ec857a683..21d638641f 100644
--- a/src/validation/__tests__/FieldsOnCorrectTypeRule-test.ts
+++ b/src/validation/__tests__/FieldsOnCorrectTypeRule-test.ts
@@ -10,16 +10,49 @@ import { buildSchema } from '../../utilities/buildASTSchema';
 import { validate } from '../validate';
 import { FieldsOnCorrectTypeRule } from '../rules/FieldsOnCorrectTypeRule';
 
-import { expectValidationErrors } from './harness';
+import { expectValidationErrorsWithSchema } from './harness';
 
 function expectErrors(queryStr: string) {
-  return expectValidationErrors(FieldsOnCorrectTypeRule, queryStr);
+  return expectValidationErrorsWithSchema(
+    testSchema,
+    FieldsOnCorrectTypeRule,
+    queryStr,
+  );
 }
 
 function expectValid(queryStr: string) {
   expectErrors(queryStr).to.deep.equal([]);
 }
 
+const testSchema = buildSchema(`
+  interface Pet {
+    name: String
+  }
+
+  type Dog implements Pet {
+    name: String
+    nickname: String
+    barkVolume: Int
+  }
+
+  type Cat implements Pet {
+    name: String
+    nickname: String
+    meowVolume: Int
+  }
+
+  union CatOrDog = Cat | Dog
+
+  type Human {
+    name: String
+    pets: [Pet]
+  }
+
+  type Query {
+    human: Human
+  }
+`);
+
 describe('Validate: Fields on correct type', () => {
   it('Object field selection', () => {
     expectValid(`
@@ -237,7 +270,7 @@ describe('Validate: Fields on correct type', () => {
     `).to.deep.equal([
       {
         message:
-          'Cannot query field "name" on type "CatOrDog". Did you mean to use an inline fragment on "Being", "Pet", "Canine", "Cat", or "Dog"?',
+          'Cannot query field "name" on type "CatOrDog". Did you mean to use an inline fragment on "Pet", "Cat", or "Dog"?',
         locations: [{ line: 3, column: 9 }],
       },
     ]);
@@ -332,7 +365,7 @@ describe('Validate: Fields on correct type', () => {
     });
 
     it('Sort type suggestions based on inheritance order', () => {
-      const schema = buildSchema(`
+      const interfaceSchema = buildSchema(`
         interface T { bar: String }
         type Query { t: T }
 
@@ -352,9 +385,27 @@ describe('Validate: Fields on correct type', () => {
         }
       `);
 
-      expectErrorMessage(schema, '{ t { foo } }').to.equal(
+      expectErrorMessage(interfaceSchema, '{ t { foo } }').to.equal(
         'Cannot query field "foo" on type "T". Did you mean to use an inline fragment on "Z", "Y", or "X"?',
       );
+
+      const unionSchema = buildSchema(`
+        interface Animal { name: String }
+        interface Mammal implements Animal { name: String }
+
+        interface Canine implements Animal & Mammal { name: String }
+        type Dog implements Animal & Mammal & Canine { name: String }
+
+        interface Feline implements Animal & Mammal { name: String }
+        type Cat implements Animal & Mammal & Feline { name: String }
+
+        union CatOrDog = Cat | Dog
+        type Query { catOrDog: CatOrDog }
+      `);
+
+      expectErrorMessage(unionSchema, '{ catOrDog { name } }').to.equal(
+        'Cannot query field "name" on type "CatOrDog". Did you mean to use an inline fragment on "Animal", "Mammal", "Canine", "Dog", or "Feline"?',
+      );
     });
 
     it('Limits lots of type suggestions', () => {
diff --git a/src/validation/__tests__/PossibleFragmentSpreadsRule-test.ts b/src/validation/__tests__/PossibleFragmentSpreadsRule-test.ts
index 267dbd3b38..c93d4d6457 100644
--- a/src/validation/__tests__/PossibleFragmentSpreadsRule-test.ts
+++ b/src/validation/__tests__/PossibleFragmentSpreadsRule-test.ts
@@ -1,17 +1,70 @@
 import { describe, it } from 'mocha';
 
+import { buildSchema } from '../../utilities/buildASTSchema';
+
 import { PossibleFragmentSpreadsRule } from '../rules/PossibleFragmentSpreadsRule';
 
-import { expectValidationErrors } from './harness';
+import { expectValidationErrorsWithSchema } from './harness';
 
 function expectErrors(queryStr: string) {
-  return expectValidationErrors(PossibleFragmentSpreadsRule, queryStr);
+  return expectValidationErrorsWithSchema(
+    testSchema,
+    PossibleFragmentSpreadsRule,
+    queryStr,
+  );
 }
 
 function expectValid(queryStr: string) {
   expectErrors(queryStr).to.deep.equal([]);
 }
 
+const testSchema = buildSchema(`
+  interface Being {
+    name: String
+  }
+
+  interface Pet implements Being {
+    name: String
+  }
+
+  type Dog implements Being & Pet {
+    name: String
+    barkVolume: Int
+  }
+
+  type Cat implements Being & Pet {
+    name: String
+    meowVolume: Int
+  }
+
+  union CatOrDog = Cat | Dog
+
+  interface Intelligent {
+    iq: Int
+  }
+
+  type Human implements Being & Intelligent {
+    name: String
+    pets: [Pet]
+    iq: Int
+  }
+
+  type Alien implements Being & Intelligent {
+    name: String
+    iq: Int
+  }
+
+  union DogOrHuman = Dog | Human
+
+  union HumanOrAlien = Human | Alien
+
+  type Query {
+    catOrDog: CatOrDog
+    dogOrHuman: DogOrHuman
+    humanOrAlien: HumanOrAlien
+  }
+`);
+
 describe('Validate: Possible fragment spreads', () => {
   it('of the same object', () => {
     expectValid(`
diff --git a/src/validation/__tests__/harness.ts b/src/validation/__tests__/harness.ts
index 8d6beccc25..139827af11 100644
--- a/src/validation/__tests__/harness.ts
+++ b/src/validation/__tests__/harness.ts
@@ -12,20 +12,16 @@ import { validate, validateSDL } from '../validate';
 import type { ValidationRule, SDLValidationRule } from '../ValidationContext';
 
 export const testSchema: GraphQLSchema = buildSchema(`
-  interface Being {
-    name(surname: Boolean): String
-  }
-
   interface Mammal {
     mother: Mammal
     father: Mammal
   }
 
-  interface Pet implements Being {
+  interface Pet {
     name(surname: Boolean): String
   }
 
-  interface Canine implements Mammal & Being {
+  interface Canine implements Mammal {
     name(surname: Boolean): String
     mother: Canine
     father: Canine
@@ -37,7 +33,7 @@ export const testSchema: GraphQLSchema = buildSchema(`
     DOWN
   }
 
-  type Dog implements Being & Pet & Mammal & Canine {
+  type Dog implements Pet & Mammal & Canine {
     name(surname: Boolean): String
     nickname: String
     barkVolume: Int
@@ -49,7 +45,7 @@ export const testSchema: GraphQLSchema = buildSchema(`
     father: Dog
   }
 
-  type Cat implements Being & Pet {
+  type Cat implements Pet {
     name(surname: Boolean): String
     nickname: String
     meows: Boolean
@@ -59,27 +55,12 @@ export const testSchema: GraphQLSchema = buildSchema(`
 
   union CatOrDog = Cat | Dog
 
-  interface Intelligent {
-    iq: Int
-  }
-
-  type Human implements Being & Intelligent {
+  type Human {
     name(surname: Boolean): String
     pets: [Pet]
     relatives: [Human]
-    iq: Int
   }
 
-  type Alien implements Being & Intelligent {
-    name(surname: Boolean): String
-    numEyes: Int
-    iq: Int
-  }
-
-  union DogOrHuman = Dog | Human
-
-  union HumanOrAlien = Human | Alien
-
   enum FurColor {
     BROWN
     BLACK
@@ -120,13 +101,10 @@ export const testSchema: GraphQLSchema = buildSchema(`
 
   type QueryRoot {
     human(id: ID): Human
-    alien: Alien
     dog: Dog
     cat: Cat
     pet: Pet
     catOrDog: CatOrDog
-    dogOrHuman: DogOrHuman
-    humanOrAlien: HumanOrAlien
     complicatedArgs: ComplicatedArgs
   }
 
diff --git a/src/validation/__tests__/validation-test.ts b/src/validation/__tests__/validation-test.ts
index ed68d68788..af8508912f 100644
--- a/src/validation/__tests__/validation-test.ts
+++ b/src/validation/__tests__/validation-test.ts
@@ -23,12 +23,14 @@ describe('Validate: Supports full validation', () => {
   it('validates queries', () => {
     const doc = parse(`
       query {
-        catOrDog {
-          ... on Cat {
-            furColor
-          }
-          ... on Dog {
-            isHouseTrained
+        human {
+          pets {
+            ... on Cat {
+              meowsVolume
+            }
+            ... on Dog {
+              barkVolume
+            }
           }
         }
       }
@@ -60,12 +62,14 @@ describe('Validate: Supports full validation', () => {
 
     const doc = parse(`
       query {
-        catOrDog {
-          ... on Cat {
-            furColor
-          }
-          ... on Dog {
-            isHouseTrained
+        human {
+          pets {
+            ... on Cat {
+              meowsVolume
+            }
+            ... on Dog {
+              barkVolume
+            }
           }
         }
       }
@@ -75,9 +79,9 @@ describe('Validate: Supports full validation', () => {
     const errorMessages = errors.map((error) => error.message);
 
     expect(errorMessages).to.deep.equal([
-      'Cannot query field "catOrDog" on type "QueryRoot". Did you mean "catOrDog"?',
-      'Cannot query field "furColor" on type "Cat". Did you mean "furColor"?',
-      'Cannot query field "isHouseTrained" on type "Dog". Did you mean "isHouseTrained"?',
+      'Cannot query field "human" on type "QueryRoot". Did you mean "human"?',
+      'Cannot query field "meowsVolume" on type "Cat". Did you mean "meowsVolume"?',
+      'Cannot query field "barkVolume" on type "Dog". Did you mean "barkVolume"?',
     ]);
   });