fix: getSourceFile fail fixed if file is not defined in tsconfig

fixes palantir/tslint#4135

Author: roman.vasilev

src/create-program.ts

@@ -8,7 +8,7 @@ type CreateProgramArgument = {
     projectDirectory?: string;
 };
 
-export function createProgram({ configFile, projectDirectory = path.dirname(configFile), compilerOptions = {} }: CreateProgramArgument): ts.Program {
+export function createProgram({ configFile, projectDirectory = path.dirname(configFile), compilerOptions = {} }: CreateProgramArgument) {
     const { config, error } = ts.readConfigFile(configFile, ts.sys.readFile);
     if (error !== undefined) {
         throw new Error(ts.formatDiagnostics([error], {
@@ -48,5 +48,5 @@ export function createProgram({ configFile, projectDirectory = path.dirname(conf
     const host = ts.createCompilerHost(parsed.options, true);
     const program = ts.createProgram(parsed.fileNames, parsed.options, host);
 
-    return program;
+    return { program, host };
 }

src/get-source-file.ts

@@ -31,6 +31,16 @@ describe('tsconfig-files', () => {
         const sourceFile = service.getSourceFile(testFile);
         assert(sourceFile);
     });
+
+    it('typescript checker (file which is not defined in tsconfig)', () => {
+        const testFile = `${root}/test-project/file.spec.ts`;
+        const sourceFile = service.getSourceFile(testFile);
+        const checker = service.getProgram().getTypeChecker();
+        const [itstmt] = sourceFile.statements.filter(x => x.getText() === `it('example test');`);
+        const itid = (itstmt as any).expression.expression;
+        const symbol = checker.getSymbolAtLocation(itid);
+        assert(symbol);
+    });
 });
 
 describe('create service', () => {

src/index.spec.ts

@@ -1,25 +1,32 @@
 import * as ts from 'typescript';
 import { createProgram } from './create-program';
-import { getSourceFile } from './get-source-file';
 
 type createServiceOptions = {
     configFile: string;
     compilerOptions?: ts.CompilerOptions;
 };
 
 export function createService({ compilerOptions, configFile }: createServiceOptions) {
-    const program = createProgram({ configFile, compilerOptions });
-    return {
+    let { program, host } = createProgram({ configFile, compilerOptions });
+    const api = {
         getProgram: () => program,
-        getSourceFile: (fileName: string, sourceText: string | undefined = ts.sys.readFile(fileName)) => {
-            return getSourceFile(program, fileName, sourceText);
+        getSourceFile: (fileName: string, sourceText?: string) => {
+            // todo: fix me optimization sourceText is not used
+            let sourceFile = program.getSourceFile(fileName);
+            if (sourceFile === undefined) {
+                const rootFileNames = [...program.getRootFileNames(), fileName];
+                program = ts.createProgram(rootFileNames, program.getCompilerOptions(), host, program);
+                sourceFile = program.getSourceFile(fileName);
+            }
+            return sourceFile;
         },
         getDiagnostics: (fileName: string, sourceText?: string) => {
-            const sourceFile = getSourceFile(program, fileName, sourceText);
+            const sourceFile = api.getSourceFile(fileName, sourceText);
             return [
                 ...program.getSyntacticDiagnostics(sourceFile),
                 ...program.getSemanticDiagnostics(sourceFile),
             ];
         },
     };
+    return api;
 }

src/index.ts

@@ -1,2 +1,3 @@
 import { x } from './file';
+it('example test');
 console.assert(x);