fix --compiler flag

appveyor.yml

@@ -16,6 +16,6 @@ install:
   - npm install
 
 test_script:
-  - npm run test-only
+  - appveyor-retry npm run test-only
 
 build: off

lib/elm-test.js

@@ -105,15 +105,13 @@ if (args.compiler === undefined) {
   }
 } else {
   try {
-    pathToElmBinary = which.sync(path.resolve(args.compiler));
+    pathToElmBinary = path.resolve(which.sync(args.compiler));
 
     elmVersion = spawn
       .sync(pathToElmBinary, ['--version'], { encoding: 'utf-8' })
       .stdout.trim();
   } catch (error) {
-    throw new Error(
-      'The --compiler option must be given a path to an elm executable.'
-    );
+    throw new Error('The elm executable passed to --compiler must exist.');
   }
 }
 

tests/fixtures/.gitignore

@@ -1,2 +1,3 @@
 /elm-stuff/
 /scratch/
+/dummy-bin/different-elm*

tests/flags.js

@@ -10,7 +10,7 @@ const xml2js = require('xml2js');
 const readline = require('readline');
 const stripAnsi = require('strip-ansi');
 
-const { fixturesDir, spawnOpts } = require('./util');
+const { fixturesDir, spawnOpts, dummyBinPath } = require('./util');
 
 const elmTestPath = path.join(__dirname, '..', 'bin', 'elm-test');
 
@@ -265,7 +265,16 @@ describe('flags', () => {
     }).timeout(60000);
   });
 
-  describe('--compiler', () => {
+  describe.only('--compiler', () => {
+    before(() => {
+      // Warning: this assumes the directory structure of the elm npm module.
+      //          It may break with new npm versions of elm.
+      const ext = process.platform === 'win32' ? '.exe' : '';
+      const elmExe = require.resolve('elm/bin/elm' + ext);
+      shell.mkdir('-p', dummyBinPath);
+      shell.cp(elmExe, path.join(dummyBinPath, 'different-elm' + ext));
+    });
+
     it("Should fail if the given compiler can't be executed", () => {
       const runResult = execElmTest([
         'elm-test',
@@ -275,7 +284,27 @@ describe('flags', () => {
 
       assert.ok(Number.isInteger(runResult.status));
       assert.notEqual(runResult.status, 0);
-    }).timeout(5000); // This sometimes needs more time to run on Travis.
+    }).timeout(5000);
+
+    it('Should work with different elm on PATH', () => {
+      const runResult = execElmTest([
+        'elm-test',
+        '--compiler=different-elm',
+        path.join('tests', 'Passing', 'One.elm'),
+      ]);
+
+      assert.equal(runResult.status, 0);
+    });
+
+    it('Should work with local different elm', () => {
+      const runResult = execElmTest([
+        'elm-test',
+        '--compiler=./dummy-bin/different-elm',
+        path.join('tests', 'Passing', 'One.elm'),
+      ]);
+
+      assert.equal(runResult.status, 0);
+    }).timeout(5000);
   });
 
   describe('--watch', () => {

tests/util.js

@@ -3,13 +3,18 @@ const path = require('path');
 const fixturesDir = path.join(__dirname, 'fixtures');
 
 const elmHome = path.join(fixturesDir, 'elm-home');
-
+const dummyBinPath = path.join(fixturesDir, 'dummy-bin');
+const newPath = process.env.PATH + path.delimiter + dummyBinPath;
 const spawnOpts = {
   silent: true,
-  env: Object.assign({ ELM_HOME: elmHome }, process.env),
+  env: Object.assign({ ELM_HOME: elmHome }, process.env, {
+    PATH: newPath,
+    Path: newPath,
+  }),
 };
 
 module.exports = {
   fixturesDir,
   spawnOpts,
+  dummyBinPath,
 };