Support for 'textDocument/hover'

packages/interface/src/GraphQLLanguageService.js

@@ -24,6 +24,7 @@ import type {
   Uri,
 } from 'graphql-language-service-types';
 import type {Position} from 'graphql-language-service-utils';
+import type {Hover} from 'vscode-languageserver-types';
 
 import {
   FRAGMENT_DEFINITION,
@@ -46,6 +47,7 @@ import {
 
 import {parse, print} from 'graphql';
 import {getAutocompleteSuggestions} from './getAutocompleteSuggestions';
+import {getHoverInformation} from './getHoverInformation';
 import {validateQuery, getRange, SEVERITY} from './getDiagnostics';
 import {
   getDefinitionQueryResultForFragmentSpread,
@@ -177,6 +179,22 @@ export class GraphQLLanguageService {
     return [];
   }
 
+  async getHoverInformation(
+    query: string,
+    position: Position,
+    filePath: Uri,
+  ): Promise<Hover.contents> {
+    const projectConfig = this._graphQLConfig.getConfigForFile(filePath);
+    const schema = await this._graphQLCache
+      .getSchema(projectConfig.projectName)
+      .catch(() => null);
+
+    if (schema) {
+      return getHoverInformation(schema, query, position);
+    }
+    return '';
+  }
+
   async getDefinition(
     query: string,
     position: Position,

packages/interface/src/__tests__/__schema__/HoverTestSchema.graphql

@@ -0,0 +1,37 @@
+schema {
+  query: Query
+}
+
+""" This is type documentation for Chicken """
+scalar Chicken
+
+""" docs for color """
+enum Color {
+  RED
+  GREEN
+  BLUE
+}
+
+union UnionType = String | Float | Boolean
+
+interface TestInterface {
+  id: String!
+}
+
+""" This is type documentation for TestType """
+type TestType implements TestInterface {
+  """ This is field documentation for TestType.testField """
+  testField: String
+  testDeprecatedField: Float @deprecated(reason: "deprecation reason")
+  testEnumField: Color
+}
+
+type Query {
+
+  """ This is field documentation for Query.thing """
+  thing: TestType
+  listOfThing: [TestType!]
+  parameterizedField(id: String!): TestType
+  cluck: Chicken
+  unionField: UnionType
+}

packages/interface/src/__tests__/getHoverInformation-test.js

@@ -0,0 +1,119 @@
+/**
+ *  Copyright (c) Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the license found in the
+ *  LICENSE file in the root directory of this source tree.
+ *
+ *  @flow
+ */
+
+import type {Hover} from 'vscode-languageserver-types';
+
+import {expect} from 'chai';
+import {beforeEach, describe, it} from 'mocha';
+import fs from 'fs';
+import {buildSchema} from 'graphql';
+import {Position} from 'graphql-language-service-utils';
+import path from 'path';
+
+import {getHoverInformation} from '../getHoverInformation';
+
+describe('getHoverInformation', () => {
+  let schema;
+  beforeEach(async () => {
+    const schemaIDL = fs.readFileSync(
+      path.join(__dirname, '__schema__/HoverTestSchema.graphql'),
+      'utf8',
+    );
+    schema = buildSchema(schemaIDL);
+  });
+
+  function testHover(query: string, point: Position): Hover.contents {
+    return getHoverInformation(schema, query, point);
+  }
+
+  it('provides leaf field information', () => {
+    const actual = testHover(
+      'query { thing { testField } }',
+      new Position(0, 20),
+    );
+    expect(actual).to.deep.equal(
+      'TestType.testField: String\n\n This is field documentation for TestType.testField',
+    );
+  });
+
+  it('provides aliased field information', () => {
+    const actual = testHover(
+      'query { thing { other: testField } }',
+      new Position(0, 25),
+    );
+    expect(actual).to.deep.equal(
+      'TestType.testField: String\n\n This is field documentation for TestType.testField',
+    );
+  });
+
+  it('provides intermediate field information', () => {
+    const actual = testHover(
+      'query { thing { testField } }',
+      new Position(0, 10),
+    );
+    expect(actual).to.deep.equal(
+      'Query.thing: TestType\n\n This is field documentation for Query.thing',
+    );
+  });
+
+  it('provides list field information', () => {
+    const actual = testHover(
+      'query { listOfThing { testField } }',
+      new Position(0, 10),
+    );
+    expect(actual).to.deep.equal('Query.listOfThing: [TestType!]');
+  });
+
+  it('provides deprecated field information', () => {
+    const actual = testHover(
+      'query { thing { testDeprecatedField } }',
+      new Position(0, 20),
+    );
+    expect(actual).to.deep.equal(
+      'TestType.testDeprecatedField: Float\n\nDeprecated: deprecation reason',
+    );
+  });
+
+  it('provides enum field information', () => {
+    const actual = testHover(
+      'query { thing { testEnumField } }',
+      new Position(0, 20),
+    );
+    expect(actual).to.deep.equal('TestType.testEnumField: Color');
+  });
+
+  it('provides scalar field information', () => {
+    const actual = testHover('query { cluck }', new Position(0, 10));
+    expect(actual).to.deep.equal('Query.cluck: Chicken');
+  });
+
+  it('provides parameter type information', () => {
+    const actual = testHover(
+      'query { parameterizedField(id: "foo") { testField } }',
+      new Position(0, 28),
+    );
+    expect(actual).to.deep.equal('Query.parameterizedField(id: String!)');
+  });
+
+  it('provides directive information', () => {
+    const actual = testHover(
+      'query { thing { testField @skip(if:true) } }',
+      new Position(0, 30),
+    );
+    expect(actual).to.deep.equal(
+      '@skip\n\nDirects the executor to skip this field or fragment when the `if` argument is true.',
+    );
+  });
+
+  it('provides union information', () => {
+    const actual = testHover('query { unionField }', new Position(0, 12));
+    expect(actual).to.deep.equal('Query.unionField: UnionType');
+  });
+});

packages/interface/src/getAutocompleteSuggestions.js

@@ -375,7 +375,10 @@ function getSuggestionsForDirective(
   return [];
 }
 
-function getTokenAtPosition(queryText: string, cursor: Position): ContextToken {
+export function getTokenAtPosition(
+  queryText: string,
+  cursor: Position,
+): ContextToken {
   let styleAtCursor = null;
   let stateAtCursor = null;
   let stringAtCursor = null;
@@ -513,7 +516,10 @@ function canUseDirective(
 
 // Utility for collecting rich type information given any token's state
 // from the graphql-mode parser.
-function getTypeInfo(schema: GraphQLSchema, tokenState: State): TypeInfo {
+export function getTypeInfo(
+  schema: GraphQLSchema,
+  tokenState: State,
+): TypeInfo {
   let argDef;
   let argDefs;
   let directiveDef;