diff --git a/Jakefile b/Jakefile
index 34879a56691..821f755650c 100644
--- a/Jakefile
+++ b/Jakefile
@@ -82,7 +82,8 @@ var harnessSources = [
     return path.join(harnessDirectory, f);
 }).concat([
 	"services/colorization.ts",
-    "services/documentRegistry.ts"
+    "services/documentRegistry.ts",
+    "services/preProcessFile.ts"
 ].map(function (f) {
     return path.join(unittestsDirectory, f);
 }));
diff --git a/tests/cases/unittests/services/preProcessFile.ts b/tests/cases/unittests/services/preProcessFile.ts
new file mode 100644
index 00000000000..6a55b53c2d5
--- /dev/null
+++ b/tests/cases/unittests/services/preProcessFile.ts
@@ -0,0 +1,101 @@
+/// <reference path="..\..\..\..\src\harness\external\mocha.d.ts" />
+/// <reference path="..\..\..\..\src\harness\harnessLanguageService.ts" />
+
+describe('preProcessFile', function () {
+    function test(sourceText: string, readImportFile: boolean, expectedPreProcess: ts.PreProcessedFileInfo): void {
+        debugger
+        var resultPreProcess = ts.preProcessFile(sourceText, readImportFile);
+
+        var resultIsLibFile = resultPreProcess.isLibFile;
+        var resultImportedFiles = resultPreProcess.importedFiles;
+        var resultReferencedFiles = resultPreProcess.referencedFiles;
+
+        var expectedIsLibFile = expectedPreProcess.isLibFile;
+        var expectedImportedFiles = expectedPreProcess.importedFiles;
+        var expectedReferencedFiles = expectedPreProcess.referencedFiles;
+
+        assert.equal(resultIsLibFile, expectedIsLibFile, "Pre-processed file has different value for isLibFile. Expected: " + expectedPreProcess + ". Actual: " + resultIsLibFile);
+
+        assert.equal(resultImportedFiles.length, expectedImportedFiles.length,
+            "Array's length of imported files does not match expected. Expected: " + expectedImportedFiles.length + ". Actual: " + resultImportedFiles.length);
+
+        assert.equal(resultReferencedFiles.length, expectedReferencedFiles.length,
+            "Array's length of referenced files does not match expected. Expected: " + expectedReferencedFiles.length + ". Actual: " + resultReferencedFiles.length);
+
+        for (var i = 0; i < expectedImportedFiles.length; ++i) {
+            var resultImportedFile = resultImportedFiles[i];
+            var expectedImportedFile = expectedImportedFiles[i];
+
+            assert.equal(resultImportedFile.path, expectedImportedFile.path, "Imported file path does not match expected. Expected: " + expectedImportedFile.path + ". Actual: " + resultImportedFile.path + ".");
+            
+            assert.equal(resultImportedFile.position, expectedImportedFile.position, "Imported file position does not match expected. Expected: " + expectedImportedFile.position + ". Actual: " + resultImportedFile.position + ".");
+
+            assert.equal(resultImportedFile.length, expectedImportedFile.length, "Imported file length does not match expected. Expected: " + expectedImportedFile.length + ". Actual: " + resultImportedFile.length + ".");
+        }
+
+        for (var i = 0; i < expectedReferencedFiles.length; ++i) {
+            var resultReferencedFile = resultReferencedFiles[i];
+            var expectedReferencedFile = expectedReferencedFiles[i];
+
+            assert.equal(resultReferencedFile.path, expectedReferencedFile.path, "Referenced file path does not match expected. Expected: " + expectedReferencedFile.path + ". Actual: " + resultReferencedFile.path + ".");
+            
+            assert.equal(resultReferencedFile.position, expectedReferencedFile.position, "Referenced file position does not match expected. Expected: " + expectedReferencedFile.position + ". Actual: " + resultReferencedFile.position + ".");
+
+            assert.equal(resultReferencedFile.length, expectedReferencedFile.length, "Referenced file length does not match expected. Expected: " + expectedReferencedFile.length + ". Actual: " + resultReferencedFile.length + ".");
+        }
+    }
+    describe("test preProcessFiles", function () {
+        it("Correctly return referenced files from triple slash", function () {
+           test("///<reference path = \"refFile1.ts\" />" + "\n" + "///<reference path =\"refFile2.ts\"/>" + "\n" + "///<reference path=\"refFile3.ts\" />" + "\n" + "///<reference path= \"refFile4d.ts\" />", true,
+                {
+                    referencedFiles: [{ path: "refFile1.ts", position: 0, length: 37  }, { path: "refFile2.ts", position: 38, length: 35 },
+                        { path: "refFile3.ts", position: 74, length: 35 }, { path: "refFile4d.ts", position: 110, length: 37 }],
+                    importedFiles: <ts.IFileReference[]>[],
+                    diagnostics: <TypeScript.Diagnostic[]>[],
+                    isLibFile: false
+                });
+       }),
+
+       it("Invalid referenced files from triple slash", function () {
+           test("///<reference path\"refFile1.ts\" />" + "\n" + "///<reference path =\"refFile2.ts\">" + "\n" + "///<referencepath=\"refFile3.ts\" />" + "\n" + "///<reference pat= \"refFile4d.ts\" />", true,
+                {
+                    referencedFiles: <ts.IFileReference[]>[],
+                    importedFiles: <ts.IFileReference[]>[],
+                    diagnostics: <TypeScript.Diagnostic[]>[],
+                    isLibFile: false
+                });
+        });
+
+        it("Correctly return imported files", function () {
+            test("import i1 = require(\"r1.ts\"); import i2 =require(\"r2.ts\"); import i3= require(\"r3.ts\"); import i4=require(\"r4.ts\"); import i5 = require  (\"r5.ts\");", true,
+                {
+                    referencedFiles: <ts.IFileReference[]>[],
+                    importedFiles: [{ path: "r1.ts", position: 0, length: 5 }, { path: "r2.ts", position: 30, length: 5 }, { path: "r3.ts", position: 59, length: 5 },
+                        { path: "r4.ts", position: 88, length: 5 }, { path: "r5.ts", position: 116, length: 5 }],
+                    diagnostics: <TypeScript.Diagnostic[]>[],
+                    isLibFile: false
+                });
+        });
+
+        it("Do not return imported files if readImportFiles argument is false", function () {
+            test("import i1 = require(\"r1.ts\"); import i2 =require(\"r2.ts\"); import i3= require(\"r3.ts\"); import i4=require(\"r4.ts\"); import i5 = require  (\"r5.ts\");", false,
+                {
+                    referencedFiles: <ts.IFileReference[]>[],
+                    importedFiles: <ts.IFileReference[]>[],
+                    diagnostics: <TypeScript.Diagnostic[]>[],
+                    isLibFile: false
+                });
+        });
+
+        it("Correctly return referenced files and import files", function () {
+            test("///<reference path=\"refFile1.ts\" />" + "\n" + "///<reference path =\"refFile2.ts\"/>" + "\n" + "import i1 = require(\"r1.ts\"); import i2 =require(\"r2.ts\");", true,
+                {
+                    referencedFiles: [{ path: "refFile1.ts", position: 0, length: 35 }, { path: "refFile2.ts", position: 36, length: 35 }],
+                    importedFiles: [{ path: "r1.ts", position: 72, length: 5 }, { path: "r2.ts", position: 102, length: 5 }],
+                    diagnostics: <TypeScript.Diagnostic[]>[],
+                    isLibFile: false
+                });
+        });
+    });
+});
+