Support tsconfig.json in tests

Author: RyanCavanaugh

src/harness/harness.ts

@@ -839,6 +839,7 @@ namespace Harness {
                     const sourceFile = createSourceFileAndAssertInvariants(fileName, file.content, scriptTarget);
                     const path = ts.toPath(file.unitName, currentDirectory, getCanonicalFileName);
                     fileMap.set(path, sourceFile);
+                    fileMap.set(<ts.Path>fileName, sourceFile);
                 }
             }
 
@@ -875,8 +876,8 @@ namespace Harness {
                 getCanonicalFileName,
                 useCaseSensitiveFileNames: () => useCaseSensitiveFileNames,
                 getNewLine: () => newLine,
-                fileExists: fileName => getSourceFile(fileName, ts.ScriptTarget.ES5) !== undefined,
-                readFile: (fileName: string): string => { throw new Error("NotYetImplemented"); }
+                fileExists: fileName => fileMap.contains(<ts.Path>ts.normalizePath(fileName)),
+                readFile: (fileName: string): string => fileMap.get(<ts.Path>ts.normalizePath(fileName)).getText()
             };
         }