(fix/test): resolve reproducibility issues w/ execWithCache

- had removed some duplicate execs in the previous commit in order to
  speed up tests so that exec wouldn't need to be re-run
  - but this caused reproducibility issues, as if you change a test
    to `it.only` temporarily, it would fail hard as nothing would be
    exec'd if it weren't the first test
    - this uses an `execWithCache` function to instead naive "cache"
      the output and not re-run the same command twice-in-a-row
      - only works with sequential tests, but good enough for now
      - similar to a beforeAll() for a group of the same test, but no
        nesting or confusing variables in describe scope

- N.B. no need for stageName in cache function or something more
  complex because each stage is parallelized as multi-process

test/tests/tsdx-build-default.test.js

@@ -1,5 +1,6 @@
 const shell = require('shelljs');
 const util = require('../fixtures/util');
+const { execWithCache } = require('../utils/shell');
 
 shell.config.silent = false;
 
@@ -13,7 +14,7 @@ describe('tsdx build :: zero-config defaults', () => {
   });
 
   it('should compile files into a dist directory', () => {
-    const output = shell.exec('node ../dist/index.js build');
+    const output = execWithCache('node ../dist/index.js build');
 
     expect(shell.test('-f', 'dist/index.js')).toBeTruthy();
     expect(
@@ -30,16 +31,24 @@ describe('tsdx build :: zero-config defaults', () => {
   });
 
   it('should create the library correctly', () => {
+    const output = execWithCache('node ../dist/index.js build');
+
     const lib = require(`../../${stageName}/dist`);
     expect(lib.foo()).toBe('bar');
     expect(lib.__esModule).toBe(true);
+
+    expect(output.code).toBe(0);
   });
 
   it('should clean the dist directory before rebuilding', () => {
+    let output = execWithCache('node ../dist/index.js build');
+    expect(output.code).toBe(0);
+
     shell.mv('package.json', 'package-og.json');
     shell.mv('package2.json', 'package.json');
 
-    const output = shell.exec('node ../dist/index.js build');
+    // cache bust because we want to re-run this command with new package.json
+    output = execWithCache('node ../dist/index.js build', { noCache: true });
     expect(shell.test('-f', 'dist/index.js')).toBeTruthy();
 
     // build-default files have been cleaned out

test/tests/tsdx-build-invalid.test.js

@@ -1,5 +1,6 @@
 const shell = require('shelljs');
 const util = require('../fixtures/util');
+const { execWithCache } = require('../utils/shell');
 
 shell.config.silent = false;
 
@@ -13,12 +14,12 @@ describe('tsdx build :: invalid build', () => {
   });
 
   it('should fail gracefully with exit code 1 when build failed', () => {
-    const code = shell.exec('node ../dist/index.js build').code;
-    expect(code).toBe(1);
+    const output = execWithCache('node ../dist/index.js build');
+    expect(output.code).toBe(1);
   });
 
   it('should only transpile and not type check', () => {
-    const code = shell.exec('node ../dist/index.js build --transpileOnly').code;
+    const output = execWithCache('node ../dist/index.js build --transpileOnly');
 
     expect(shell.test('-f', 'dist/index.js')).toBeTruthy();
     expect(
@@ -31,7 +32,7 @@ describe('tsdx build :: invalid build', () => {
 
     expect(shell.test('-f', 'dist/index.d.ts')).toBeTruthy();
 
-    expect(code).toBe(0);
+    expect(output.code).toBe(0);
   });
 
   afterAll(() => {

test/tests/tsdx-build-withTsconfig.test.js

@@ -1,5 +1,6 @@
 const shell = require('shelljs');
 const util = require('../fixtures/util');
+const { execWithCache } = require('../utils/shell');
 
 shell.config.silent = false;
 
@@ -13,7 +14,7 @@ describe('tsdx build :: build with custom tsconfig.json options', () => {
   });
 
   it('should use the declarationDir when set', () => {
-    const output = shell.exec('node ../dist/index.js build');
+    const output = execWithCache('node ../dist/index.js build');
 
     expect(shell.test('-f', 'dist/index.js')).toBeTruthy();
     expect(
@@ -32,13 +33,17 @@ describe('tsdx build :: build with custom tsconfig.json options', () => {
   });
 
   it('should set __esModule according to esModuleInterop', () => {
+    const output = execWithCache('node ../dist/index.js build');
+
     const lib = require(`../../${stageName}/dist/build-withtsconfig.cjs.production.min.js`);
     // if esModuleInterop: false, no __esModule is added, therefore undefined
     expect(lib.__esModule).toBe(undefined);
+
+    expect(output.code).toBe(0);
   });
 
   it('should read custom --tsconfig path', () => {
-    const output = shell.exec(
+    const output = execWithCache(
       'node ../dist/index.js build --format cjs --tsconfig ./src/tsconfig.json'
     );
 

test/utils/shell.js

@@ -0,0 +1,29 @@
+// this file contains helper utils for working with shell.js functions
+const shell = require('shelljs');
+
+shell.config.silent = true;
+
+// simple shell.exec "cache" that doesn't re-run the same command twice in a row
+let prevCommand = '';
+let prevCommandOutput = {};
+function execWithCache(command, { noCache = false } = {}) {
+  // return the old output
+  if (!noCache && prevCommand === command) return prevCommandOutput;
+
+  const output = shell.exec(command);
+
+  // reset if command is not to be cached
+  if (noCache) {
+    prevCommand = '';
+    prevCommandOutput = {};
+  } else {
+    prevCommand = command;
+    prevCommandOutput = output;
+  }
+
+  return output;
+}
+
+module.exports = {
+  execWithCache,
+};