From bd3a27ed5219e94cb83401b125aee923d19aaf4d Mon Sep 17 00:00:00 2001
From: Ryan Cavanaugh <RyanCavanaugh@users.noreply.github.com>
Date: Tue, 12 Dec 2017 16:11:37 -0800
Subject: [PATCH 1/2] Clear the module resolution cache when new @types appear

---
 src/server/editorServices.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index a5b09c6a63f..b147a5c3e92 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -547,9 +547,11 @@ namespace ts.server {
             }
             switch (response.kind) {
                 case ActionSet:
+                    project.resolutionCache.clear();
                     this.typingsCache.updateTypingsForProject(response.projectName, response.compilerOptions, response.typeAcquisition, response.unresolvedImports, response.typings);
                     break;
                 case ActionInvalidate:
+                    project.resolutionCache.clear();
                     this.typingsCache.deleteTypingsForProject(response.projectName);
                     break;
             }

From 9e122d030586dadbaf41f60a93c85816a027bbd7 Mon Sep 17 00:00:00 2001
From: Ryan Cavanaugh <RyanCavanaugh@users.noreply.github.com>
Date: Tue, 12 Dec 2017 17:22:41 -0800
Subject: [PATCH 2/2] Fix test

---
 src/harness/unittests/typingsInstaller.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/harness/unittests/typingsInstaller.ts b/src/harness/unittests/typingsInstaller.ts
index cb2d350744c..f7820434469 100644
--- a/src/harness/unittests/typingsInstaller.ts
+++ b/src/harness/unittests/typingsInstaller.ts
@@ -1009,7 +1009,7 @@ namespace ts.projectSystem {
             installer.installAll(/*expectedCount*/ 1);
         });
 
-        it("cached unresolved typings are not recomputed if program structure did not change", () => {
+        it("should recompute resolutions after typings are installed", () => {
             const host = createServerHost([]);
             const session = createSession(host);
             const f = {
@@ -1051,7 +1051,7 @@ namespace ts.projectSystem {
             session.executeCommand(changeRequest);
             host.checkTimeoutQueueLengthAndRun(2); // This enqueues the updategraph and refresh inferred projects
             const version2 = proj.getCachedUnresolvedImportsPerFile_TestOnly().getVersion();
-            assert.equal(version1, version2, "set of unresolved imports should not change");
+            assert.notEqual(version1, version2, "set of unresolved imports should change");
         });
     });