added a snapshot

src/logger.ts

@@ -1,6 +1,5 @@
 import * as fs from 'fs';
 import * as path from 'path';
-import { JestConfig } from './jest-types';
 
 /**
  * Logger file that enables logging things just once. Does this by traversing the array of previously recorded
@@ -9,35 +8,24 @@ import { JestConfig } from './jest-types';
  */
 
 const logs: any[] = [];
-let loggingDisabled: boolean = true;
 let logsFlushed: boolean = false;
 
-export function enableLoggingIfNeeded(config: JestConfig) {
-  if (
-    config.globals &&
-    config.globals['ts-jest'] &&
-    config.globals['ts-jest'].debug
-  ) {
-    loggingDisabled = false;
-    logOnce('Logging enabled');
-  }
+function shouldLog(): boolean {
+  // If the env variable is set and the logs have not already been flushed, log the line
+  return process.env.TS_JEST_DEBUG && !logsFlushed;
 }
 
+// Log function. Only logs prior to calls to flushLogs.
 export function logOnce(...thingsToLog: any[]) {
-  if (loggingDisabled) {
+  if (!shouldLog()) {
     return;
   }
-  thingsToLog.forEach(msg => {
-    if (includes(logs, msg)) {
-      return; // Message has already been logged
-    }
-    logs.push(msg);
-  });
+  logs.push(thingsToLog);
 }
 
 // This function JSONifies logs and flushes them to disk.
 export function flushLogs() {
-  if (loggingDisabled || logsFlushed) {
+  if (!shouldLog()) {
     return; // only output stuff for the first invocation and if logging is enabled.
   }
   logsFlushed = true;
@@ -56,6 +44,6 @@ function convertToJSONIfPossible(object: any): string {
   try {
     return JSON.stringify(object, null, 2);
   } catch {
-    return object; // if unable to parse, simply return.
+    return object.toString(); // if unable to parse, simply return the string variant
   }
 }

src/preprocessor.ts

@@ -1,7 +1,7 @@
 import * as crypto from 'crypto';
 import * as tsc from 'typescript';
 import { JestConfig, Path, TransformOptions } from './jest-types';
-import { enableLoggingIfNeeded, flushLogs, logOnce } from './logger';
+import { flushLogs, logOnce } from './logger';
 import { getPostProcessHook } from './postprocess';
 import {
   cacheFile,
@@ -16,7 +16,6 @@ export function process(
   jestConfig: JestConfig,
   transformOptions: TransformOptions = { instrument: false },
 ) {
-  enableLoggingIfNeeded(jestConfig);
   // transformOptions.instrument is a proxy for collectCoverage
   // https://github.com/kulshekhar/ts-jest/issues/201#issuecomment-300572902
   const compilerOptions = getTSConfig(

src/utils.ts

@@ -4,6 +4,7 @@ import * as fsExtra from 'fs-extra';
 import * as path from 'path';
 import * as tsc from 'typescript';
 import { JestConfig, TsJestConfig } from './jest-types';
+import { logOnce } from './logger';
 
 export function getTSJestConfig(globals: any): TsJestConfig {
   return globals && globals['ts-jest'] ? globals['ts-jest'] : {};
@@ -121,8 +122,6 @@ export function getTSConfig(globals, collectCoverage: boolean = false) {
   let configPath = getTSConfigPathFromConfig(globals);
   const skipBabel = getTSJestConfig(globals).skipBabel;
 
-  logOnce('Original tsConfig before modifications: ', config);
-
   // check cache before resolving configuration
   // NB: We use JSON.stringify() to create a consistent, unique signature. Although it lacks a uniform
   //     shape, this is simpler and faster than using the crypto package to generate a hash signature.
@@ -136,6 +135,7 @@ export function getTSConfig(globals, collectCoverage: boolean = false) {
   }
 
   const config = readCompilerOptions(configPath);
+  logOnce('Original typescript config before modifications: ', config);
 
   // ts-jest will map lines numbers properly if inlineSourceMap and
   // inlineSources are set to true. For testing, we don't need the

tests/__helpers__/runJest.ts

@@ -11,7 +11,7 @@ const JEST_PATH = 'jest';
 // return the result of the spawned proccess:
 //  [ 'status', 'signal', 'output', 'pid', 'stdout', 'stderr',
 //    'envPairs', 'options', 'args', 'file' ]
-export default function runJest(dir: string, args: string[]): Result {
+export default function runJest(dir: string, args: string[], env = {}): Result {
   const isRelative = dir[0] !== '/';
 
   if (isRelative) {
@@ -30,6 +30,7 @@ export default function runJest(dir: string, args: string[]): Result {
 
   const result = spawnSync(JEST_PATH, args || [], {
     cwd: dir,
+    env,
   });
 
   // Call to string on byte arrays and strip ansi color codes for more accurate string comparison.

tests/__tests__/__snapshots__/debug.spec.ts.snap

@@ -0,0 +1,42 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Debug output should create a debug file with the correct output if the flag is set 1`] = `
+"[
+  \\"Original typescript config before modifications: \\",
+  {
+    \\"target\\": 1,
+    \\"module\\": 1,
+    \\"moduleResolution\\": 2,
+    \\"noEmitOnError\\": false,
+    \\"jsx\\": 2,
+    \\"allowJs\\": true,
+    \\"inlineSourceMap\\": true,
+    \\"inlineSources\\": true
+  }
+]
+[
+  \\"final compilerOptions:\\",
+  {
+    \\"target\\": 1,
+    \\"module\\": 1,
+    \\"moduleResolution\\": 2,
+    \\"noEmitOnError\\": false,
+    \\"jsx\\": 2,
+    \\"allowJs\\": true,
+    \\"inlineSourceMap\\": true,
+    \\"inlineSources\\": true
+  }
+]
+[
+  \\"tsJestConfig: \\",
+  {}
+]
+[
+  \\"Using babel with options:\\",
+  {
+    \\"babelrc\\": false,
+    \\"plugins\\": [],
+    \\"presets\\": []
+  }
+]"
+`;

tests/__tests__/debug.spec.ts

@@ -4,12 +4,16 @@ import runJest from '../__helpers__/runJest';
 
 describe('Debug output', () => {
   it('should create a debug file with the correct output if the flag is set', async () => {
-    runJest('../debug', ['--no-cache', '-u']);
+    runJest('../debug', ['--no-cache', '-u'], {
+      TS_JEST_DEBUG: 'true',
+    });
     const logFile = fs.readFileSync(
       path.resolve(__dirname, '../debug/node_modules/ts-jest/debug.txt'),
       'utf-8',
     );
+
     expect(logFile).not.toBeNull();
+    expect(logFile).toMatchSnapshot(); // Ensure we have some actual output that doesn't change
   });
 
   it('Should not create a file if the debug flag is not set', () => {

tests/debug/package.json

@@ -20,9 +20,6 @@
       "json"
     ],
     "globals": {
-      "ts-jest": {
-        "debug": true
-      }
     }
   }
 }