Deprecate 'printError' function

.eslintrc.yml

@@ -627,6 +627,7 @@ overrides:
     rules:
       internal-rules/require-to-string-tag: off
       node/no-unpublished-import: [error, { allowModules: ['chai', 'mocha'] }]
+      import/no-deprecated: off
       import/no-restricted-paths: off
       import/no-extraneous-dependencies: [error, { devDependencies: true }]
   - files: 'integrationTests/*'

resources/gen-changelog.js

@@ -12,6 +12,9 @@ const labelsConfig = {
   'PR: breaking change 💥': {
     section: 'Breaking Change 💥',
   },
+  'PR: deprecation ⚠': {
+    section: 'Deprecation ⚠',
+  },
   'PR: feature 🚀': {
     section: 'New Feature 🚀',
   },

src/error/GraphQLError.ts

@@ -198,7 +198,21 @@ export class GraphQLError extends Error {
   }
 
   toString(): string {
-    return printError(this);
+    let output = this.message;
+
+    if (this.nodes) {
+      for (const node of this.nodes) {
+        if (node.loc) {
+          output += '\n\n' + printLocation(node.loc);
+        }
+      }
+    } else if (this.source && this.locations) {
+      for (const location of this.locations) {
+        output += '\n\n' + printSourceLocation(this.source, location);
+      }
+    }
+
+    return output;
   }
 
   // FIXME: workaround to not break chai comparisons, should be remove in v16
@@ -210,21 +224,9 @@ export class GraphQLError extends Error {
 /**
  * Prints a GraphQLError to a string, representing useful location information
  * about the error's position in the source.
+ *
+ * @deprecated Please use `error.toString` instead. Will be removed in v17
  */
 export function printError(error: GraphQLError): string {
-  let output = error.message;
-
-  if (error.nodes) {
-    for (const node of error.nodes) {
-      if (node.loc) {
-        output += '\n\n' + printLocation(node.loc);
-      }
-    }
-  } else if (error.source && error.locations) {
-    for (const location of error.locations) {
-      output += '\n\n' + printSourceLocation(error.source, location);
-    }
-  }
-
-  return output;
+  return error.toString();
 }

src/error/__tests__/GraphQLError-test.ts

@@ -132,18 +132,23 @@ describe('GraphQLError', () => {
   });
 });
 
-describe('printError', () => {
+describe('toString', () => {
+  it('Deprecated: prints an error using printError', () => {
+    const error = new GraphQLError('Error');
+    expect(printError(error)).to.equal('Error');
+  });
+
   it('prints an error without location', () => {
     const error = new GraphQLError('Error without location');
-    expect(printError(error)).to.equal('Error without location');
+    expect(error.toString()).to.equal('Error without location');
   });
 
   it('prints an error using node without location', () => {
     const error = new GraphQLError(
       'Error attached to node without location',
       parse('{ foo }', { noLocation: true }),
     );
-    expect(printError(error)).to.equal(
+    expect(error.toString()).to.equal(
       'Error attached to node without location',
     );
   });
@@ -182,7 +187,7 @@ describe('printError', () => {
       fieldB.type,
     ]);
 
-    expect(printError(error)).to.equal(dedent`
+    expect(error.toString()).to.equal(dedent`
       Example error with two nodes
 
       SourceA:2:10