chore: add some tests and refactor tsconfig path resolution

packages/typescript-estree/src/tsconfig-parser.ts

@@ -50,6 +50,12 @@ function diagnosticReporter(diagnostic: ts.Diagnostic): void {
 
 const noopFileWatcher = { close: () => {} };
 
+function getTsconfigPath(tsconfigPath: string, extra: Extra): string {
+  return path.isAbsolute(tsconfigPath)
+    ? tsconfigPath
+    : path.join(extra.tsconfigRootDir || process.cwd(), tsconfigPath);
+}
+
 /**
  * Calculate project environments using options provided by consumer and paths from config
  * @param code The code being linted
@@ -64,7 +70,6 @@ export function calculateProjectParserOptions(
   extra: Extra,
 ): ts.Program[] {
   const results = [];
-  const tsconfigRootDir = extra.tsconfigRootDir;
 
   // preserve reference to code and file being linted
   currentLintOperationState.code = code;
@@ -77,11 +82,8 @@ export function calculateProjectParserOptions(
     watchCallback(filePath, ts.FileWatcherEventKind.Changed);
   }
 
-  for (let tsconfigPath of extra.projects) {
-    // if absolute paths aren't provided, make relative to tsconfigRootDir
-    if (!path.isAbsolute(tsconfigPath)) {
-      tsconfigPath = path.join(tsconfigRootDir, tsconfigPath);
-    }
+  for (let rawTsconfigPath of extra.projects) {
+    const tsconfigPath = getTsconfigPath(rawTsconfigPath, extra);
 
     const existingWatch = knownWatchProgramMap.get(tsconfigPath);
 
@@ -193,12 +195,7 @@ export function createProgram(code: string, filePath: string, extra: Extra) {
     return undefined;
   }
 
-  let tsconfigPath = extra.projects[0];
-
-  // if absolute paths aren't provided, make relative to tsconfigRootDir
-  if (!path.isAbsolute(tsconfigPath)) {
-    tsconfigPath = path.join(extra.tsconfigRootDir, tsconfigPath);
-  }
+  const tsconfigPath = getTsconfigPath(extra.projects[0], extra);
 
   const commandLine = ts.getParsedCommandLineOfConfigFile(
     tsconfigPath,

packages/typescript-estree/tests/lib/semanticInfo.ts

@@ -48,6 +48,21 @@ describe('semanticInfo', () => {
     );
   });
 
+  it(`should cache the created ts.program`, () => {
+    const filename = testFiles[0];
+    const code = readFileSync(filename, 'utf8');
+    const options = createOptions(filename);
+    const optionsProjectString = {
+      ...options,
+      project: './tsconfig.json',
+    };
+    expect(
+      parseAndGenerateServices(code, optionsProjectString).services.program,
+    ).toBe(
+      parseAndGenerateServices(code, optionsProjectString).services.program,
+    );
+  });
+
   it(`should handle "project": "./tsconfig.json" and "project": ["./tsconfig.json"] the same`, () => {
     const filename = testFiles[0];
     const code = readFileSync(filename, 'utf8');
@@ -65,6 +80,38 @@ describe('semanticInfo', () => {
     );
   });
 
+  it(`should resolve absolute and relative tsconfig paths the same`, () => {
+    const filename = testFiles[0];
+    const code = readFileSync(filename, 'utf8');
+    const options = createOptions(filename);
+    const optionsAbsolutePath = {
+      ...options,
+      project: `${__dirname}/../fixtures/semanticInfo/tsconfig.json`,
+    };
+    const optionsRelativePath = {
+      ...options,
+      project: `./tsconfig.json`,
+    };
+    const absolutePathResult = parseAndGenerateServices(
+      code,
+      optionsAbsolutePath,
+    );
+    const relativePathResult = parseAndGenerateServices(
+      code,
+      optionsRelativePath,
+    );
+    if (absolutePathResult.services.program === undefined) {
+      throw new Error('Unable to create ts.program for absolute tsconfig');
+    } else if (relativePathResult.services.program === undefined) {
+      throw new Error('Unable to create ts.program for relative tsconfig');
+    }
+    expect(
+      absolutePathResult.services.program.getResolvedProjectReferences(),
+    ).toEqual(
+      relativePathResult.services.program.getResolvedProjectReferences(),
+    );
+  });
+
   // case-specific tests
   it('isolated-file tests', () => {
     const fileName = resolve(FIXTURES_DIR, 'isolated-file.src.ts');