fix: properly output chained Typescript errors (#390)

* fix: properly output chained TypeScript errors

Author: connorjsmith

src/ApiIncrementalChecker.ts

@@ -1,3 +1,4 @@
+import * as ts from 'typescript'; // used for types only
 import {
   IncrementalCheckerInterface,
   IncrementalCheckerParams
@@ -13,6 +14,7 @@ import { LintReport } from './types/eslint';
 
 export class ApiIncrementalChecker implements IncrementalCheckerInterface {
   protected readonly tsIncrementalCompiler: CompilerHost;
+  protected readonly typescript: typeof ts;
 
   private currentEsLintErrors = new Map<string, LintReport>();
   private lastUpdatedFiles: string[] = [];
@@ -41,6 +43,8 @@ export class ApiIncrementalChecker implements IncrementalCheckerInterface {
       resolveModuleName,
       resolveTypeReferenceDirective
     );
+
+    this.typescript = typescript;
   }
 
   public hasEsLinter(): boolean {
@@ -60,7 +64,10 @@ export class ApiIncrementalChecker implements IncrementalCheckerInterface {
     this.lastUpdatedFiles = tsDiagnostics.updatedFiles;
     this.lastRemovedFiles = tsDiagnostics.removedFiles;
 
-    return createIssuesFromTsDiagnostics(tsDiagnostics.results);
+    return createIssuesFromTsDiagnostics(
+      tsDiagnostics.results,
+      this.typescript
+    );
   }
 
   public async getEsLintIssues(cancellationToken: CancellationToken) {

src/IncrementalChecker.ts

@@ -246,7 +246,7 @@ export class IncrementalChecker implements IncrementalCheckerInterface {
       tsDiagnostics.push(...tsDiagnosticsToRegister);
     });
 
-    return createIssuesFromTsDiagnostics(tsDiagnostics);
+    return createIssuesFromTsDiagnostics(tsDiagnostics, this.typescript);
   }
 
   public async getEsLintIssues(

src/issue/typescript/TypeScriptIssueFactory.ts

@@ -3,38 +3,10 @@ import { deduplicateAndSortIssues, Issue } from '../Issue';
 import { IssueOrigin } from '../IssueOrigin';
 import { IssueSeverity } from '../IssueSeverity';
 
-/**
- * Based on the TypeScript source - not used directly from the `typescript`
- * package as there is an option to pass a custom TypeScript instance.
- */
-function flattenDiagnosticMessageText(
-  messageText: string | ts.DiagnosticMessageChain
-) {
-  if (typeof messageText === 'string') {
-    return messageText;
-  } else {
-    let diagnosticChain: ts.DiagnosticMessageChain | undefined = messageText;
-    let flattenMessageText = '';
-    let indent = 0;
-
-    while (diagnosticChain) {
-      if (indent) {
-        flattenMessageText += '\n';
-        for (let i = 0; i < indent; i++) {
-          flattenMessageText += '  ';
-        }
-      }
-
-      flattenMessageText += diagnosticChain.messageText;
-      indent++;
-      diagnosticChain = diagnosticChain.next;
-    }
-
-    return flattenMessageText;
-  }
-}
-
-function createIssueFromTsDiagnostic(diagnostic: ts.Diagnostic): Issue {
+function createIssueFromTsDiagnostic(
+  diagnostic: ts.Diagnostic,
+  typescript: typeof ts
+): Issue {
   let file: string | undefined;
   let line: number | undefined;
   let character: number | undefined;
@@ -57,15 +29,26 @@ function createIssueFromTsDiagnostic(diagnostic: ts.Diagnostic): Issue {
     // we don't handle Suggestion and Message diagnostics
     severity:
       diagnostic.category === 0 ? IssueSeverity.WARNING : IssueSeverity.ERROR,
-    message: flattenDiagnosticMessageText(diagnostic.messageText),
+    message: typescript.flattenDiagnosticMessageText(
+      diagnostic.messageText,
+      '\n'
+    ),
     file,
     line,
     character
   };
 }
 
-function createIssuesFromTsDiagnostics(diagnostic: ts.Diagnostic[]): Issue[] {
-  return deduplicateAndSortIssues(diagnostic.map(createIssueFromTsDiagnostic));
+function createIssuesFromTsDiagnostics(
+  diagnostics: ts.Diagnostic[],
+  typescript: typeof ts
+): Issue[] {
+  function createIssueFromTsDiagnosticWithFormatter(diagnostic: ts.Diagnostic) {
+    return createIssueFromTsDiagnostic(diagnostic, typescript);
+  }
+  return deduplicateAndSortIssues(
+    diagnostics.map(createIssueFromTsDiagnosticWithFormatter)
+  );
 }
 
 export { createIssueFromTsDiagnostic, createIssuesFromTsDiagnostics };

test/unit/issue/typescript/TypeScriptIssueFactory.spec.ts

@@ -2,10 +2,66 @@ import {
   createIssueFromTsDiagnostic,
   createIssuesFromTsDiagnostics
 } from '../../../../lib/issue';
-import { Diagnostic } from 'typescript';
+import * as ts from 'typescript';
+
+function makeDiagnosticMessageChainTestCase(): ts.Diagnostic {
+  const version: number = Number.parseFloat(ts.versionMajorMinor);
+  if (version <= 3.5) {
+    return ({
+      start: 12,
+      code: 1221,
+      category: 0,
+      length: 3,
+      file: undefined,
+      messageText: {
+        messageText: 'Cannot assign object to the string type',
+        category: 0,
+        code: 1221,
+        next: {
+          messageText: 'Another ident message',
+          category: 0,
+          code: 1221,
+          next: {
+            messageText: 'The most ident message',
+            category: 0,
+            code: 1221
+          }
+        }
+      }
+    } as unknown) as ts.Diagnostic;
+  } else {
+    // newer versions of typescript have the |next| property as an array
+    return ({
+      start: 12,
+      code: 1221,
+      category: 0,
+      length: 3,
+      file: undefined,
+      messageText: {
+        messageText: 'Cannot assign object to the string type',
+        category: 0,
+        code: 1221,
+        next: [
+          {
+            messageText: 'Another ident message',
+            category: 0,
+            code: 1221,
+            next: [
+              {
+                messageText: 'The most ident message',
+                category: 0,
+                code: 1221
+              }
+            ]
+          }
+        ]
+      }
+    } as unknown) as ts.Diagnostic;
+  }
+}
 
 describe('[UNIT] issue/typescript/TypeScriptIssueFactory', () => {
-  const TS_DIAGNOSTIC_WARNING: Diagnostic = {
+  const TS_DIAGNOSTIC_WARNING: ts.Diagnostic = {
     start: 100,
     code: 4221,
     category: 1,
@@ -20,7 +76,7 @@ describe('[UNIT] issue/typescript/TypeScriptIssueFactory', () => {
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
     } as any
   };
-  const TS_DIAGNOSTIC_ERROR: Diagnostic = {
+  const TS_DIAGNOSTIC_ERROR: ts.Diagnostic = {
     start: 12,
     code: 1221,
     category: 0,
@@ -35,44 +91,23 @@ describe('[UNIT] issue/typescript/TypeScriptIssueFactory', () => {
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
     } as any
   };
-  const TS_DIAGNOSTIC_WITHOUT_FILE: Diagnostic = {
+  const TS_DIAGNOSTIC_WITHOUT_FILE: ts.Diagnostic = {
     start: 12,
     code: 1221,
     category: 0,
     length: 1,
     messageText: 'Cannot assign object to the string type',
     file: undefined
   };
-  const TS_DIAGNOSTIC_MESSAGE_CHAIN: Diagnostic = {
-    start: 12,
-    code: 1221,
-    category: 0,
-    length: 3,
-    file: undefined,
-    messageText: {
-      messageText: 'Cannot assign object to the string type',
-      category: 0,
-      code: 1221,
-      next: {
-        messageText: 'Another ident message',
-        category: 0,
-        code: 1221,
-        next: {
-          messageText: 'The most ident message',
-          category: 0,
-          code: 1221
-        }
-      }
-    }
-  };
+  const TS_DIAGNOSTIC_MESSAGE_CHAIN: ts.Diagnostic = makeDiagnosticMessageChainTestCase();
 
   it.each([
     [TS_DIAGNOSTIC_WARNING],
     [TS_DIAGNOSTIC_ERROR],
     [TS_DIAGNOSTIC_WITHOUT_FILE],
     [TS_DIAGNOSTIC_MESSAGE_CHAIN]
   ])('creates Issue from TsDiagnostic: %p', tsDiagnostic => {
-    const issue = createIssueFromTsDiagnostic(tsDiagnostic);
+    const issue = createIssueFromTsDiagnostic(tsDiagnostic, ts);
 
     expect(issue).toMatchSnapshot();
   });
@@ -87,7 +122,7 @@ describe('[UNIT] issue/typescript/TypeScriptIssueFactory', () => {
       ]
     ]
   ])('creates Issues from TsDiagnostics: %p', tsDiagnostics => {
-    const issues = createIssuesFromTsDiagnostics(tsDiagnostics);
+    const issues = createIssuesFromTsDiagnostics(tsDiagnostics, ts);
 
     expect(issues).toMatchSnapshot();
   });

test/unit/issue/typescript/__snapshots__/TypeScriptIssueFactory.spec.ts.snap

@@ -91,4 +91,4 @@ Array [
     "severity": "error",
   },
 ]
-`;
+`;