Merge branch 'catch-syntax-errors' into combine-prs

src/transpiler.ts

@@ -30,8 +30,34 @@ function transpileViaTranspileModule(
   fileSource: string,
   compilerOptions: ts.CompilerOptions,
 ): ts.TranspileOutput {
-  return ts.transpileModule(fileSource, {
+  const transpileOutput = ts.transpileModule(fileSource, {
     compilerOptions,
     fileName: filePath,
+    reportDiagnostics: true,
   });
+  const {diagnostics} = transpileOutput;
+
+  if (diagnostics.length > 0) {
+    const errors = formatDiagnostics(diagnostics);
+    logOnce(logMessageForTranspilationErrors(errors));
+    // Maybe we should keep compiling even though there are errors. This can possibly be configured.
+    throw createTranspilationError(errors);
+  }
+
+  return transpileOutput;
+}
+
+function formatDiagnostics(diagnostics: ts.Diagnostic[]): string {
+  // TODO consider using ts.formatDiagnosticsWithColorAndContext()
+  return `${diagnostics.map(d => d.messageText)}\n`;
+}
+
+function createTranspilationError(errors: string): Error {
+    return Error(
+      `TypeScript compiler encountered syntax errors while transpiling. Errors: ${errors}`,
+    );
+}
+
+function logMessageForTranspilationErrors(errors: string): string {
+  return `Diagnostic errors from TSC: ${errors}`;
 }

tests/__tests__/transpiler.spec.ts

@@ -0,0 +1,23 @@
+import { transpileTypescript } from '../../src/transpiler';
+import * as ts from 'typescript';
+
+describe('transpileTypescript', () => {
+
+  const compilerOptions: ts.CompilerOptions = {newLine: ts.NewLineKind.LineFeed};
+
+  it('should transpile valid TS syntax', () => {
+    const result = transpileTypescript('valid.ts', 'var a = true;', compilerOptions);
+    expect(result.code).toBe('var a = true;\n');
+  });
+
+  it('should transpile valid TS syntax with type errors', () => {
+    const result = transpileTypescript('valid.ts', 'var a: string = true;', compilerOptions);
+    expect(result.code).toBe('var a = true;\n');
+  });
+
+  it('should throw an error when transpiling invalid TS syntax', () => {
+    expect(() => {
+      transpileTypescript('invalid.ts', 'var a = ;', compilerOptions);
+    }).toThrow('TypeScript compiler encountered syntax errors while transpiling. Errors: Expression expected.');
+  });
+});