Improve validation error for unused variable

Author: leebyron

src/validation/__tests__/NoUnusedVariables.js

@@ -15,9 +15,9 @@ import {
 } from '../rules/NoUnusedVariables';
 
 
-function unusedVar(varName, line, column) {
+function unusedVar(varName, opName, line, column) {
   return {
-    message: unusedVariableMessage(varName),
+    message: unusedVariableMessage(varName, opName),
     locations: [ { line, column } ],
   };
 }
@@ -26,7 +26,7 @@ describe('Validate: No unused variables', () => {
 
   it('uses all variables', () => {
     expectPassesRule(NoUnusedVariables, `
-      query Foo($a: String, $b: String, $c: String) {
+      query ($a: String, $b: String, $c: String) {
         field(a: $a, b: $b, c: $c)
       }
     `);
@@ -113,11 +113,11 @@ describe('Validate: No unused variables', () => {
 
   it('variable not used', () => {
     expectFailsRule(NoUnusedVariables, `
-      query Foo($a: String, $b: String, $c: String) {
+      query ($a: String, $b: String, $c: String) {
         field(a: $a, b: $b)
       }
     `, [
-      unusedVar('c', 2, 41)
+      unusedVar('c', null, 2, 38)
     ]);
   });
 
@@ -127,8 +127,8 @@ describe('Validate: No unused variables', () => {
         field(b: $b)
       }
     `, [
-      unusedVar('a', 2, 17),
-      unusedVar('c', 2, 41)
+      unusedVar('a', 'Foo', 2, 17),
+      unusedVar('c', 'Foo', 2, 41)
     ]);
   });
 
@@ -151,7 +151,7 @@ describe('Validate: No unused variables', () => {
         field
       }
     `, [
-      unusedVar('c', 2, 41)
+      unusedVar('c', 'Foo', 2, 41)
     ]);
   });
 
@@ -174,8 +174,8 @@ describe('Validate: No unused variables', () => {
         field
       }
     `, [
-      unusedVar('a', 2, 17),
-      unusedVar('c', 2, 41)
+      unusedVar('a', 'Foo', 2, 17),
+      unusedVar('c', 'Foo', 2, 41)
     ]);
   });
 
@@ -191,7 +191,7 @@ describe('Validate: No unused variables', () => {
         field(b: $b)
       }
     `, [
-      unusedVar('b', 2, 17)
+      unusedVar('b', 'Foo', 2, 17)
     ]);
   });
 
@@ -210,8 +210,8 @@ describe('Validate: No unused variables', () => {
         field(b: $b)
       }
     `, [
-      unusedVar('b', 2, 17),
-      unusedVar('a', 5, 17)
+      unusedVar('b', 'Foo', 2, 17),
+      unusedVar('a', 'Bar', 5, 17)
     ]);
   });
 

src/validation/rules/NoUnusedVariables.js

@@ -12,8 +12,13 @@ import type { ValidationContext } from '../index';
 import { GraphQLError } from '../../error';
 
 
-export function unusedVariableMessage(varName: string): string {
-  return `Variable "$${varName}" is never used.`;
+export function unusedVariableMessage(
+  varName: string,
+  opName: ?string
+): string {
+  return opName ?
+    `Variable "$${varName}" is never used in operation "${opName}".` :
+    `Variable "$${varName}" is never used.`;
 }
 
 /**
@@ -33,6 +38,7 @@ export function NoUnusedVariables(context: ValidationContext): any {
       leave(operation) {
         const variableNameUsed = Object.create(null);
         const usages = context.getRecursiveVariableUsages(operation);
+        const opName = operation.name ? operation.name.value : null;
 
         usages.forEach(({ node }) => {
           variableNameUsed[node.name.value] = true;
@@ -42,7 +48,7 @@ export function NoUnusedVariables(context: ValidationContext): any {
           const variableName = variableDef.variable.name.value;
           if (variableNameUsed[variableName] !== true) {
             context.reportError(new GraphQLError(
-              unusedVariableMessage(variableName),
+              unusedVariableMessage(variableName, opName),
               [ variableDef ]
             ));
           }