Report errors from antlr through logger (#46)

Mismatched or extraneous input encountered during parsing will
produce error messages that include the location of the error.
Two tests are added to FSHImporter.test.ts for these errors.

src/import/FSHErrorListener.ts

@@ -0,0 +1,27 @@
+import { ErrorListener } from 'antlr4/error';
+import { logger } from '../utils/FSHLogger';
+import { Recognizer, Token } from 'antlr4';
+
+export class FSHErrorListener extends ErrorListener {
+  constructor(readonly file: string) {
+    super();
+  }
+
+  syntaxError(
+    recognizer: Recognizer,
+    offendingSymbol: Token,
+    line: number,
+    column: number,
+    msg: string
+  ): void {
+    logger.error(msg, {
+      file: this.file,
+      location: {
+        startLine: line,
+        startColumn: column + 1,
+        endLine: line,
+        endColumn: column + offendingSymbol.text.length
+      }
+    });
+  }
+}

src/import/importText.ts

@@ -4,6 +4,7 @@ import { FSHParser } from './generated/FSHParser';
 import { DocContext } from './parserContexts';
 import { FSHImporter } from './FSHImporter';
 import { FSHDocument } from './FSHDocument';
+import { FSHErrorListener } from './FSHErrorListener';
 
 /**
  * Parses a text string as a FSHDocument.
@@ -13,17 +14,26 @@ import { FSHDocument } from './FSHDocument';
  */
 export function importText(text: string, file?: string): FSHDocument {
   const importer = new FSHImporter(file);
-  return importer.visitDoc(parseDoc(text));
+  return importer.visitDoc(parseDoc(text, file));
 }
 
 // NOTE: Since the ANTLR parser/lexer is JS (not typescript), we need to use some ts-ignore here.
-function parseDoc(input: string): DocContext {
+function parseDoc(input: string, file?: string): DocContext {
   const chars = new InputStream(input);
   const lexer = new FSHLexer(chars);
+  const listener = new FSHErrorListener(file);
+  // @ts-ignore
+  lexer.removeErrorListeners();
+  // @ts-ignore
+  lexer.addErrorListener(listener);
   // @ts-ignore
   const tokens = new CommonTokenStream(lexer);
   const parser = new FSHParser(tokens);
   // @ts-ignore
+  parser.removeErrorListeners();
+  // @ts-ignore
+  parser.addErrorListener(listener);
+  // @ts-ignore
   parser.buildParseTrees = true;
   // @ts-ignore
   return parser.doc() as DocContext;

test/import/FSHImporter.test.ts

@@ -1,6 +1,13 @@
 import { importText, FSHImporter, FSHDocument } from '../../src/import';
+import { logger } from '../../src/utils/FSHLogger';
 
 describe('FSHImporter', () => {
+  let mockWriter: jest.SpyInstance<boolean, [any, string, ((error: Error) => void)?]>;
+
+  beforeAll(() => {
+    mockWriter = jest.spyOn(logger.transports[0], 'write');
+  });
+
   it('should default filename to blank string', () => {
     const input = '';
     const result = importText(input);
@@ -33,4 +40,26 @@ describe('FSHImporter', () => {
     const result2 = visitor.visitDoc({ entity: () => [] });
     expect(result2).toBeUndefined();
   });
+
+  it('should report mismatched input errors from antlr', () => {
+    const input = `
+    Profile: MismatchedPizza
+    Pizza: Large
+    `;
+    importText(input, 'Pizza.fsh');
+    expect(mockWriter.mock.calls[mockWriter.mock.calls.length - 1][0].message).toMatch(
+      /File: Pizza\.fsh.*Line 3\D.*Column 5\D.*Line 3\D.*Column 10\D/s
+    );
+  });
+
+  it('should report extraneous input errors from antlr', () => {
+    const input = `
+    Profile: Something Spaced
+    Parent: Spacious
+    `;
+    importText(input, 'Space.fsh');
+    expect(mockWriter.mock.calls[mockWriter.mock.calls.length - 1][0].message).toMatch(
+      /File: Space\.fsh.*Line 2\D.*Column 24\D.*Line 2\D.*Column 29\D/s
+    );
+  });
 });