diff --git a/package-lock.json b/package-lock.json
index b3cbf6b78..9f4be7dc6 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -454,9 +454,9 @@
       "dev": true
     },
     "@types/mocha": {
-      "version": "5.2.0",
-      "resolved": "https://registry.npmjs.org/@types/mocha/-/mocha-5.2.0.tgz",
-      "integrity": "sha512-YeDiSEzznwZwwp766SJ6QlrTyBYUGPSIwmREHVTmktUYiT/WADdWtpt9iH0KuUSf8lZLdI4lP0X6PBzPo5//JQ==",
+      "version": "5.2.5",
+      "resolved": "https://registry.npmjs.org/@types/mocha/-/mocha-5.2.5.tgz",
+      "integrity": "sha512-lAVp+Kj54ui/vLUFxsJTMtWvZraZxum3w3Nwkble2dNuV5VnPA+Mi2oGX9XYJAaIvZi3tn3cbjS/qcJXRb6Bww==",
       "dev": true
     },
     "@types/mz": {
@@ -538,7 +538,6 @@
       "resolved": "https://registry.npmjs.org/align-text/-/align-text-0.1.4.tgz",
       "integrity": "sha1-DNkKVhCT810KmSVsIrcGlDP60Rc=",
       "dev": true,
-      "optional": true,
       "requires": {
         "kind-of": "^3.0.2",
         "longest": "^1.0.1",
@@ -3635,7 +3634,6 @@
           "version": "0.1.4",
           "bundled": true,
           "dev": true,
-          "optional": true,
           "requires": {
             "kind-of": "^3.0.2",
             "longest": "^1.0.1",
@@ -4792,8 +4790,7 @@
         "longest": {
           "version": "1.0.1",
           "bundled": true,
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "loose-envify": {
           "version": "1.3.1",
diff --git a/package.json b/package.json
index 6dfa9059a..c14807f53 100644
--- a/package.json
+++ b/package.json
@@ -71,7 +71,7 @@
     "@types/chai-as-promised": "7.1.0",
     "@types/glob": "5.0.35",
     "@types/lodash": "4.14.116",
-    "@types/mocha": "5.2.0",
+    "@types/mocha": "5.2.5",
     "@types/mz": "0.0.31",
     "@types/node": "7.0.63",
     "@types/object-hash": "1.2.0",
diff --git a/src/test/typescript-service-helpers.ts b/src/test/typescript-service-helpers.ts
index 097e0c834..4f553c4ad 100644
--- a/src/test/typescript-service-helpers.ts
+++ b/src/test/typescript-service-helpers.ts
@@ -1,7 +1,7 @@
 import * as chai from 'chai'
 import chaiAsPromised = require('chai-as-promised')
 import { applyReducer, Operation } from 'fast-json-patch'
-import { IBeforeAndAfterContext, ISuiteCallbackContext, ITestCallbackContext } from 'mocha'
+import { Context } from 'mocha'
 import { Observable } from 'rxjs'
 import * as sinon from 'sinon'
 import * as ts from 'typescript'
@@ -63,7 +63,7 @@ export const initializeTypeScriptService = (
     files: Map<string, string>,
     clientCapabilities: ClientCapabilities = DEFAULT_CAPABILITIES
 ) =>
-    async function(this: TestContext & IBeforeAndAfterContext): Promise<void> {
+    async function(this: TestContext & Context): Promise<void> {
         // Stub client
         this.client = sinon.createStubInstance(RemoteLanguageClient)
         this.client.textDocumentXcontent.callsFake(
@@ -107,7 +107,7 @@ export const initializeTypeScriptService = (
 /**
  * Shuts the TypeScriptService down (to be used in `afterEach()`)
  */
-export async function shutdownTypeScriptService(this: TestContext & IBeforeAndAfterContext): Promise<void> {
+export async function shutdownTypeScriptService(this: Context): Promise<void> {
     await this.service.shutdown().toPromise()
 }
 
@@ -121,7 +121,7 @@ export function describeTypeScriptService(
     shutdownService = shutdownTypeScriptService,
     rootUri: string
 ): void {
-    describe('Workspace without project files', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('Workspace without project files', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -152,8 +152,8 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        describe('textDocumentDefinition()', function(this: TestContext & ISuiteCallbackContext): void {
-            specify('in same file', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+        describe('textDocumentDefinition()', () => {
+            specify('in same file', async function(this: TestContext & Context): Promise<void> {
                 const result: Location[] = await this.service
                     .textDocumentDefinition({
                         textDocument: {
@@ -182,7 +182,7 @@ export function describeTypeScriptService(
                     },
                 ])
             })
-            specify('on keyword (non-null)', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+            specify('on keyword (non-null)', async function(this: TestContext & Context): Promise<void> {
                 const result: Location[] = await this.service
                     .textDocumentDefinition({
                         textDocument: {
@@ -197,7 +197,7 @@ export function describeTypeScriptService(
                     .toPromise()
                 assert.deepEqual(result, [])
             })
-            specify('in other file', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+            specify('in other file', async function(this: TestContext & Context): Promise<void> {
                 const result: Location[] = await this.service
                     .textDocumentDefinition({
                         textDocument: {
@@ -228,8 +228,8 @@ export function describeTypeScriptService(
             })
         })
 
-        describe('textDocumentTypeDefinition()', function(this: TestContext & ISuiteCallbackContext): void {
-            specify('in other file', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+        describe('textDocumentTypeDefinition()', () => {
+            specify('in other file', async function(this: TestContext & Context): Promise<void> {
                 const result: Location[] = await this.service
                     .textDocumentTypeDefinition({
                         textDocument: {
@@ -258,7 +258,7 @@ export function describeTypeScriptService(
                     },
                 ])
             })
-            specify('in same file', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+            specify('in same file', async function(this: TestContext & Context): Promise<void> {
                 const result: Location[] = await this.service
                     .textDocumentTypeDefinition({
                         textDocument: {
@@ -289,10 +289,8 @@ export function describeTypeScriptService(
             })
         })
 
-        describe('textDocumentXdefinition()', function(this: TestContext & ISuiteCallbackContext): void {
-            specify('on interface field reference', async function(
-                this: TestContext & ITestCallbackContext
-            ): Promise<void> {
+        describe('textDocumentXdefinition()', () => {
+            specify('on interface field reference', async function(this: TestContext & Context): Promise<void> {
                 const result: SymbolLocationInformation[] = await this.service
                     .textDocumentXdefinition({
                         textDocument: {
@@ -330,7 +328,7 @@ export function describeTypeScriptService(
                     },
                 ])
             })
-            specify('in same file', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+            specify('in same file', async function(this: TestContext & Context): Promise<void> {
                 const result: SymbolLocationInformation[] = await this.service
                     .textDocumentXdefinition({
                         textDocument: {
@@ -369,8 +367,8 @@ export function describeTypeScriptService(
                 ])
             })
         })
-        describe('textDocumentHover()', function(this: TestContext & ISuiteCallbackContext): void {
-            specify('in same file', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+        describe('textDocumentHover()', () => {
+            specify('in same file', async function(this: TestContext & Context): Promise<void> {
                 const result: Hover = await this.service
                     .textDocumentHover({
                         textDocument: {
@@ -398,7 +396,7 @@ export function describeTypeScriptService(
                 })
             })
             specify('local function with callback argument', async function(
-                this: TestContext & ITestCallbackContext
+                this: TestContext & Context
             ): Promise<void> {
                 const result: Hover = await this.service
                     .textDocumentHover({
@@ -429,7 +427,7 @@ export function describeTypeScriptService(
                     ],
                 })
             })
-            specify('in other file', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+            specify('in other file', async function(this: TestContext & Context): Promise<void> {
                 const result: Hover = await this.service
                     .textDocumentHover({
                         textDocument: {
@@ -456,7 +454,7 @@ export function describeTypeScriptService(
                     contents: [{ language: 'typescript', value: 'class Foo\nimport Foo' }, '**alias**'],
                 })
             })
-            specify('over keyword (non-null)', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+            specify('over keyword (non-null)', async function(this: TestContext & Context): Promise<void> {
                 const result: Hover = await this.service
                     .textDocumentHover({
                         textDocument: {
@@ -471,7 +469,7 @@ export function describeTypeScriptService(
                     .toPromise()
                 assert.deepEqual(result, { contents: [] })
             })
-            specify('over non-existent file', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+            specify('over non-existent file', async function(this: TestContext & Context): Promise<void> {
                 await Promise.resolve(
                     assert.isRejected(
                         this.service
@@ -491,7 +489,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('Workspace with typings directory', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('Workspace with typings directory', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -522,8 +520,8 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        describe('textDocumentDefinition()', function(this: TestContext & ISuiteCallbackContext): void {
-            specify('with tsd.d.ts', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+        describe('textDocumentDefinition()', () => {
+            specify('with tsd.d.ts', async function(this: TestContext & Context): Promise<void> {
                 const result: Location[] = await this.service
                     .textDocumentDefinition({
                         textDocument: {
@@ -552,8 +550,8 @@ export function describeTypeScriptService(
                     },
                 ])
             })
-            describe('on file in project root', function(this: TestContext & ISuiteCallbackContext): void {
-                specify('on import alias', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+            describe('on file in project root', () => {
+                specify('on import alias', async function(this: TestContext & Context): Promise<void> {
                     const result: Location[] = await this.service
                         .textDocumentDefinition({
                             textDocument: {
@@ -582,7 +580,7 @@ export function describeTypeScriptService(
                         },
                     ])
                 })
-                specify('on module name', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+                specify('on module name', async function(this: TestContext & Context): Promise<void> {
                     const result: Location[] = await this.service
                         .textDocumentDefinition({
                             textDocument: {
@@ -615,7 +613,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('DefinitelyTyped', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('DefinitelyTyped', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -718,9 +716,9 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        describe('workspaceSymbol()', function(this: TestContext & ISuiteCallbackContext): void {
+        describe('workspaceSymbol()', () => {
             it('should find a symbol by SymbolDescriptor query with name and package name', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 const result: SymbolInformation[] = await this.service
                     .workspaceSymbol({
                         symbol: { name: 'resolveCallback', package: { name: '@types/resolve' } },
@@ -748,7 +746,7 @@ export function describeTypeScriptService(
                 ])
             })
             it('should find a symbol by SymbolDescriptor query with name, containerKind and package name', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 const result: SymbolInformation[] = await this.service
                     .workspaceSymbol({
                         symbol: {
@@ -782,7 +780,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('Workspace with root package.json', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('Workspace with root package.json', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -803,10 +801,10 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        describe('workspaceSymbol()', function(this: TestContext & ISuiteCallbackContext): void {
-            describe('with SymbolDescriptor query', function(this: TestContext & ISuiteCallbackContext): void {
+        describe('workspaceSymbol()', () => {
+            describe('with SymbolDescriptor query', () => {
                 it('should find a symbol by name, kind and package name', async function(this: TestContext &
-                    ITestCallbackContext): Promise<void> {
+                    Context): Promise<void> {
                     const result: SymbolInformation[] = await this.service
                         .workspaceSymbol({
                             symbol: {
@@ -838,7 +836,7 @@ export function describeTypeScriptService(
                     })
                 })
                 it('should find a symbol by name, kind, package name and ignore package version', async function(this: TestContext &
-                    ITestCallbackContext): Promise<void> {
+                    Context): Promise<void> {
                     const result: SymbolInformation[] = await this.service
                         .workspaceSymbol({
                             symbol: { name: 'a', kind: 'class', package: { name: 'mypkg', version: '203940234' } },
@@ -863,9 +861,7 @@ export function describeTypeScriptService(
                         name: 'a',
                     })
                 })
-                it('should find a symbol by name', async function(this: TestContext & ITestCallbackContext): Promise<
-                    void
-                > {
+                it('should find a symbol by name', async function(this: TestContext & Context): Promise<void> {
                     const result: SymbolInformation[] = await this.service
                         .workspaceSymbol({
                             symbol: {
@@ -895,7 +891,7 @@ export function describeTypeScriptService(
                     ])
                 })
                 it('should return no result if the PackageDescriptor does not match', async function(this: TestContext &
-                    ITestCallbackContext): Promise<void> {
+                    Context): Promise<void> {
                     const result: SymbolInformation[] = await this.service
                         .workspaceSymbol({
                             symbol: {
@@ -911,8 +907,8 @@ export function describeTypeScriptService(
                     assert.deepEqual(result, [])
                 })
             })
-            describe('with text query', function(this: TestContext & ISuiteCallbackContext): void {
-                it('should find a symbol', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+            describe('with text query', () => {
+                it('should find a symbol', async function(this: TestContext & Context): Promise<void> {
                     const result: SymbolInformation[] = await this.service
                         .workspaceSymbol({ query: 'a' })
                         .reduce<Operation, SymbolInformation[]>(applyReducer, null as any)
@@ -938,7 +934,7 @@ export function describeTypeScriptService(
                     ])
                 })
                 it('should return all symbols for an empty query excluding dependencies', async function(this: TestContext &
-                    ITestCallbackContext): Promise<void> {
+                    Context): Promise<void> {
                     const result: SymbolInformation[] = await this.service
                         .workspaceSymbol({ query: '' })
                         .reduce<Operation, SymbolInformation[]>(applyReducer, null as any)
@@ -1107,9 +1103,8 @@ export function describeTypeScriptService(
             })
         })
 
-        describe('workspaceXreferences()', function(this: TestContext & ISuiteCallbackContext): void {
-            it('should return all references to a method', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+        describe('workspaceXreferences()', () => {
+            it('should return all references to a method', async function(this: TestContext & Context): Promise<void> {
                 const result: ReferenceInformation[] = await this.service
                     .workspaceXreferences({ query: { name: 'foo', kind: 'method', containerName: 'a' } })
                     .reduce<Operation, ReferenceInformation[]>(applyReducer, null as any)
@@ -1140,7 +1135,7 @@ export function describeTypeScriptService(
                 ])
             })
             it('should return all references to a method with hinted dependee package name', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 const result: ReferenceInformation[] = await this.service
                     .workspaceXreferences({
                         query: {
@@ -1180,7 +1175,7 @@ export function describeTypeScriptService(
                 ])
             })
             it('should return no references to a method if hinted dependee package name was not found', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 const result = await this.service
                     .workspaceXreferences({
                         query: {
@@ -1197,7 +1192,7 @@ export function describeTypeScriptService(
                 assert.deepEqual(result, [])
             })
             it('should return all references to a symbol from a dependency', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 const result: ReferenceInformation[] = await this.service
                     .workspaceXreferences({ query: { name: 'x' } })
                     .reduce<Operation, ReferenceInformation[]>(applyReducer, null as any)
@@ -1228,7 +1223,7 @@ export function describeTypeScriptService(
                 ])
             })
             it('should return all references to a symbol from a dependency with PackageDescriptor query', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 const result: ReferenceInformation[] = await this.service
                     .workspaceXreferences({ query: { name: 'x', package: { name: 'dep' } } })
                     .reduce<Operation, ReferenceInformation[]>(applyReducer, null as any)
@@ -1264,7 +1259,7 @@ export function describeTypeScriptService(
                 ])
             })
             it('should return all references to all symbols if empty SymbolDescriptor query is passed', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 const result: ReferenceInformation[] = await this.service
                     .workspaceXreferences({ query: {} })
                     .reduce<Operation, ReferenceInformation[]>(applyReducer, null as any)
@@ -1473,7 +1468,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('Dependency detection', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('Dependency detection', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -1528,10 +1523,8 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        describe('workspaceXdependencies()', function(this: TestContext & ISuiteCallbackContext): void {
-            it('should account for all dependencies', async function(this: TestContext & ITestCallbackContext): Promise<
-                void
-            > {
+        describe('workspaceXdependencies()', () => {
+            it('should account for all dependencies', async function(this: TestContext & Context): Promise<void> {
                 const result: DependencyReference[] = await this.service
                     .workspaceXdependencies()
                     .reduce<Operation, DependencyReference[]>(applyReducer, null as any)
@@ -1630,10 +1623,8 @@ export function describeTypeScriptService(
                 ])
             })
         })
-        describe('workspaceXpackages()', function(this: TestContext & ISuiteCallbackContext): void {
-            it('should accournt for all packages', async function(this: TestContext & ITestCallbackContext): Promise<
-                void
-            > {
+        describe('workspaceXpackages()', () => {
+            it('should accournt for all packages', async function(this: TestContext & Context): Promise<void> {
                 const result: PackageInformation[] = await this.service
                     .workspaceXpackages()
                     .reduce<Operation, PackageInformation[]>(applyReducer, null as any)
@@ -1747,16 +1738,14 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('TypeScript library', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('TypeScript library', () => {
         beforeEach(
             initializeTypeScriptService(createService, rootUri, new Map([[rootUri + 'a.ts', 'let parameters = [];']]))
         )
 
         afterEach(shutdownService)
 
-        specify('type of parameters should be any[]', async function(
-            this: TestContext & ITestCallbackContext
-        ): Promise<void> {
+        specify('type of parameters should be any[]', async function(this: TestContext & Context): Promise<void> {
             const result: Hover = await this.service
                 .textDocumentHover({
                     textDocument: {
@@ -1785,7 +1774,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('Live updates', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('Live updates', () => {
         beforeEach(
             initializeTypeScriptService(createService, rootUri, new Map([[rootUri + 'a.ts', 'let parameters = [];']]))
         )
@@ -1793,7 +1782,7 @@ export function describeTypeScriptService(
         afterEach(shutdownService)
 
         it('should handle didChange when configuration is not yet initialized', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+            Context): Promise<void> {
             const hoverParams = {
                 textDocument: {
                     uri: rootUri + 'a.ts',
@@ -1838,7 +1827,7 @@ export function describeTypeScriptService(
         })
 
         it('should handle didClose when configuration is not yet initialized', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+            Context): Promise<void> {
             const hoverParams = {
                 textDocument: {
                     uri: rootUri + 'a.ts',
@@ -1876,7 +1865,7 @@ export function describeTypeScriptService(
             })
         })
 
-        it('should reflect updated content', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+        it('should reflect updated content', async function(this: TestContext & Context): Promise<void> {
             const hoverParams = {
                 textDocument: {
                     uri: rootUri + 'a.ts',
@@ -1971,7 +1960,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('Diagnostics', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('Diagnostics', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -1982,9 +1971,7 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        it('should publish diagnostics on didOpen', async function(this: TestContext & ITestCallbackContext): Promise<
-            void
-        > {
+        it('should publish diagnostics on didOpen', async function(this: TestContext & Context): Promise<void> {
             await this.service.textDocumentDidOpen({
                 textDocument: {
                     uri: rootUri + 'src/errors.ts',
@@ -2009,9 +1996,7 @@ export function describeTypeScriptService(
             })
         })
 
-        it('should publish diagnostics on didChange', async function(this: TestContext & ITestCallbackContext): Promise<
-            void
-        > {
+        it('should publish diagnostics on didChange', async function(this: TestContext & Context): Promise<void> {
             await this.service.textDocumentDidOpen({
                 textDocument: {
                     uri: rootUri + 'src/errors.ts',
@@ -2047,7 +2032,7 @@ export function describeTypeScriptService(
         })
 
         it('should publish empty diagnostics on didChange if error was fixed', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+            Context): Promise<void> {
             await this.service.textDocumentDidOpen({
                 textDocument: {
                     uri: rootUri + 'src/errors.ts',
@@ -2074,9 +2059,7 @@ export function describeTypeScriptService(
             })
         })
 
-        it('should clear diagnostics on didClose', async function(this: TestContext & ITestCallbackContext): Promise<
-            void
-        > {
+        it('should clear diagnostics on didClose', async function(this: TestContext & Context): Promise<void> {
             await this.service.textDocumentDidClose({
                 textDocument: {
                     uri: rootUri + 'src/errors.ts',
@@ -2091,7 +2074,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('References and imports', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('References and imports', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -2129,9 +2112,9 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        describe('textDocumentDefinition()', function(this: TestContext & ISuiteCallbackContext): void {
+        describe('textDocumentDefinition()', () => {
             it('should resolve symbol imported with tripe-slash reference', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 const result: Location[] = await this.service
                     .textDocumentDefinition({
                         textDocument: {
@@ -2169,7 +2152,7 @@ export function describeTypeScriptService(
                 ])
             })
             it('should resolve symbol imported with import statement', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 const result: Location[] = await this.service
                     .textDocumentDefinition({
                         textDocument: {
@@ -2198,8 +2181,9 @@ export function describeTypeScriptService(
                     },
                 ])
             })
-            it('should resolve definition with missing reference', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+            it('should resolve definition with missing reference', async function(this: TestContext & Context): Promise<
+                void
+            > {
                 const result: Location[] = await this.service
                     .textDocumentDefinition({
                         textDocument: {
@@ -2228,9 +2212,7 @@ export function describeTypeScriptService(
                     },
                 ])
             })
-            it('should resolve deep definitions', async function(this: TestContext & ITestCallbackContext): Promise<
-                void
-            > {
+            it('should resolve deep definitions', async function(this: TestContext & Context): Promise<void> {
                 // This test passes only because we expect no response from LSP server
                 // for definition located in file references with depth 3 or more (a -> b -> c -> d (...))
                 // This test will fail once we'll increase (or remove) depth limit
@@ -2265,7 +2247,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('TypeScript libraries', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('TypeScript libraries', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -2286,10 +2268,8 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        describe('textDocumentHover()', function(this: TestContext & ISuiteCallbackContext): void {
-            it('should load local library file', async function(this: TestContext & ITestCallbackContext): Promise<
-                void
-            > {
+        describe('textDocumentHover()', () => {
+            it('should load local library file', async function(this: TestContext & Context): Promise<void> {
                 const result: Hover = await this.service
                     .textDocumentHover({
                         textDocument: {
@@ -2336,9 +2316,8 @@ export function describeTypeScriptService(
                 })
             })
         })
-        describe('textDocumentDefinition()', function(this: TestContext & ISuiteCallbackContext): void {
-            it('should resolve TS libraries to github URL', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+        describe('textDocumentDefinition()', () => {
+            it('should resolve TS libraries to github URL', async function(this: TestContext & Context): Promise<void> {
                 assert.deepEqual(
                     await this.service
                         .textDocumentDefinition({
@@ -2415,7 +2394,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('textDocumentReferences()', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('textDocumentReferences()', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -2452,7 +2431,7 @@ export function describeTypeScriptService(
         afterEach(shutdownService)
 
         it('should provide an empty response when no reference is found', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+            Context): Promise<void> {
             const result = await this.service
                 .textDocumentReferences({
                     textDocument: {
@@ -2469,8 +2448,7 @@ export function describeTypeScriptService(
             assert.deepEqual(result, [])
         })
 
-        it('should include the declaration if requested', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+        it('should include the declaration if requested', async function(this: TestContext & Context): Promise<void> {
             const result = await this.service
                 .textDocumentReferences({
                     textDocument: {
@@ -2501,8 +2479,9 @@ export function describeTypeScriptService(
             ])
         })
 
-        it('should provide a reference within the same file', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+        it('should provide a reference within the same file', async function(this: TestContext & Context): Promise<
+            void
+        > {
             const result = await this.service
                 .textDocumentReferences({
                     textDocument: {
@@ -2532,8 +2511,7 @@ export function describeTypeScriptService(
                 },
             ])
         })
-        it('should provide two references from imports', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+        it('should provide two references from imports', async function(this: TestContext & Context): Promise<void> {
             const result = await this.service
                 .textDocumentReferences({
                     textDocument: {
@@ -2578,7 +2556,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('textDocumentSignatureHelp()', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('textDocumentSignatureHelp()', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -2623,7 +2601,7 @@ export function describeTypeScriptService(
         afterEach(shutdownService)
 
         it('should provide a valid empty response when no signature is found', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+            Context): Promise<void> {
             const result: SignatureHelp = await this.service
                 .textDocumentSignatureHelp({
                     textDocument: {
@@ -2644,7 +2622,7 @@ export function describeTypeScriptService(
         })
 
         it('should provide signature help with parameters in the same file', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+            Context): Promise<void> {
             const result: SignatureHelp = await this.service
                 .textDocumentSignatureHelp({
                     textDocument: {
@@ -2679,8 +2657,9 @@ export function describeTypeScriptService(
             })
         })
 
-        it('should provide signature help from imported symbols', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+        it('should provide signature help from imported symbols', async function(this: TestContext & Context): Promise<
+            void
+        > {
             const result: SignatureHelp = await this.service
                 .textDocumentSignatureHelp({
                     textDocument: {
@@ -2707,7 +2686,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('textDocumentCompletion() with snippets', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('textDocumentCompletion() with snippets', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -2746,7 +2725,7 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        it('should produce completions', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+        it('should produce completions', async function(this: TestContext & Context): Promise<void> {
             const result: CompletionList = await this.service
                 .textDocumentCompletion({
                     textDocument: {
@@ -2804,8 +2783,7 @@ export function describeTypeScriptService(
             ])
         })
 
-        it('should resolve completions with snippets', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+        it('should resolve completions with snippets', async function(this: TestContext & Context): Promise<void> {
             const result: CompletionList = await this.service
                 .textDocumentCompletion({
                     textDocument: {
@@ -2880,7 +2858,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('textDocumentCompletion()', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('textDocumentCompletion()', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -2920,9 +2898,7 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        it('produces completions in the same file', async function(this: TestContext & ITestCallbackContext): Promise<
-            void
-        > {
+        it('produces completions in the same file', async function(this: TestContext & Context): Promise<void> {
             const result: CompletionList = await this.service
                 .textDocumentCompletion({
                     textDocument: {
@@ -2980,9 +2956,7 @@ export function describeTypeScriptService(
             ])
         })
 
-        it('resolves completions in the same file', async function(this: TestContext & ITestCallbackContext): Promise<
-            void
-        > {
+        it('resolves completions in the same file', async function(this: TestContext & Context): Promise<void> {
             const result: CompletionList = await this.service
                 .textDocumentCompletion({
                     textDocument: {
@@ -3049,8 +3023,7 @@ export function describeTypeScriptService(
             ])
         })
 
-        it('produces completions for imported symbols', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+        it('produces completions for imported symbols', async function(this: TestContext & Context): Promise<void> {
             const result: CompletionList = await this.service
                 .textDocumentCompletion({
                     textDocument: {
@@ -3079,8 +3052,7 @@ export function describeTypeScriptService(
                 ],
             })
         })
-        it('produces completions for referenced symbols', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+        it('produces completions for referenced symbols', async function(this: TestContext & Context): Promise<void> {
             const result: CompletionList = await this.service
                 .textDocumentCompletion({
                     textDocument: {
@@ -3109,9 +3081,7 @@ export function describeTypeScriptService(
                 ],
             })
         })
-        it('produces completions for empty files', async function(this: TestContext & ITestCallbackContext): Promise<
-            void
-        > {
+        it('produces completions for empty files', async function(this: TestContext & Context): Promise<void> {
             this.timeout(10000)
             const result: CompletionList = await this.service
                 .textDocumentCompletion({
@@ -3129,7 +3099,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('textDocumentRename()', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('textDocumentRename()', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -3161,9 +3131,7 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        it('should error on an invalid symbol', async function(this: TestContext & ITestCallbackContext): Promise<
-            void
-        > {
+        it('should error on an invalid symbol', async function(this: TestContext & Context): Promise<void> {
             await Promise.resolve(
                 assert.isRejected(
                     this.service
@@ -3184,7 +3152,7 @@ export function describeTypeScriptService(
             )
         })
         it('should return a correct WorkspaceEdit to rename a class', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+            Context): Promise<void> {
             const result: WorkspaceEdit = await this.service
                 .textDocumentRename({
                     textDocument: {
@@ -3232,7 +3200,7 @@ export function describeTypeScriptService(
             })
         })
         it('should return a correct WorkspaceEdit to rename an imported function', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+            Context): Promise<void> {
             const result: WorkspaceEdit = await this.service
                 .textDocumentRename({
                     textDocument: {
@@ -3296,7 +3264,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('textDocumentCodeAction()', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('textDocumentCodeAction()', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -3320,7 +3288,7 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        it('suggests a missing this', async function(this: TestContext & ITestCallbackContext): Promise<void> {
+        it('suggests a missing this', async function(this: TestContext & Context): Promise<void> {
             await this.service.textDocumentDidOpen({
                 textDocument: {
                     uri: rootUri + 'a.ts',
@@ -3380,7 +3348,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('workspaceExecuteCommand()', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('workspaceExecuteCommand()', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -3406,7 +3374,7 @@ export function describeTypeScriptService(
 
         describe('codeFix', () => {
             it('should apply a WorkspaceEdit for the passed FileTextChanges', async function(this: TestContext &
-                ITestCallbackContext): Promise<void> {
+                Context): Promise<void> {
                 await this.service
                     .workspaceExecuteCommand({
                         command: 'codeFix',
@@ -3452,7 +3420,7 @@ export function describeTypeScriptService(
         })
     })
 
-    describe('Special file names', function(this: TestContext & ISuiteCallbackContext): void {
+    describe('Special file names', () => {
         beforeEach(
             initializeTypeScriptService(
                 createService,
@@ -3469,8 +3437,9 @@ export function describeTypeScriptService(
 
         afterEach(shutdownService)
 
-        it('should accept files with TypeScript keywords in path', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+        it('should accept files with TypeScript keywords in path', async function(this: TestContext & Context): Promise<
+            void
+        > {
             const result: Hover = await this.service
                 .textDocumentHover({
                     textDocument: {
@@ -3497,8 +3466,9 @@ export function describeTypeScriptService(
                 contents: [{ language: 'typescript', value: 'function a(): void' }, '**function** _(exported)_'],
             })
         })
-        it('should accept files with special characters in path', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+        it('should accept files with special characters in path', async function(this: TestContext & Context): Promise<
+            void
+        > {
             const result: Hover = await this.service
                 .textDocumentHover({
                     textDocument: {
@@ -3526,7 +3496,7 @@ export function describeTypeScriptService(
             })
         })
         it('should handle Windows-style paths in triple slash references', async function(this: TestContext &
-            ITestCallbackContext): Promise<void> {
+            Context): Promise<void> {
             const result = await this.service
                 .textDocumentDefinition({
                     textDocument: {