Throw instead of warning.

Fixes #68

index.js

@@ -9,7 +9,6 @@ var temp = require("temp").track();
 var findAllDependencies = require("find-elm-dependencies").findAllDependencies;
 
 var defaultOptions     = {
-  emitWarning: console.warn,
   spawn:      spawn,
   cwd:        undefined,
   pathToElm:  undefined,
@@ -39,7 +38,7 @@ function prepareOptions(options, spawnFn) {
 
 function prepareProcessArgs(sources, options) {
   var preparedSources = prepareSources(sources);
-  var compilerArgs = compilerArgsFromOptions(options, options.emitWarning);
+  var compilerArgs = compilerArgsFromOptions(options);
 
   return ["make"].concat(preparedSources ? preparedSources.concat(compilerArgs) : compilerArgs);
 }
@@ -65,15 +64,21 @@ function runCompiler(sources, options, pathToElm) {
   return options.spawn(pathToElm, processArgs, processOpts);
 }
 
-function handleCompilerError(err, pathToElm) {
+function compilerErrorToString(err, pathToElm) {
   if ((typeof err === "object") && (typeof err.code === "string")) {
-    handleError(pathToElm, err);
+    switch (err.code) {
+      case "ENOENT":
+        return ("Could not find Elm compiler \"" + pathToElm + "\". Is it installed?")
+
+      case "EACCES":
+        return ("Elm compiler \"" + pathToElm + "\" did not have permission to run. Do you need to give it executable permissions?");
+
+      default:
+        return ("Error attempting to run Elm compiler \"" + pathToElm + "\":\n" + err);
+    }
   } else {
-    console.error("Exception thrown when attempting to run Elm compiler " + JSON.stringify(pathToElm) + ":\n");
+    return ("Exception thrown when attempting to run Elm compiler " + JSON.stringify(pathToElm) + ":\n");
   }
-  throw err;
-
-  process.exit(1);
 }
 
 function compileSync(sources, options) {
@@ -83,7 +88,7 @@ function compileSync(sources, options) {
   try {
     return runCompiler(sources, optionsWithDefaults, pathToElm);
   } catch (err) {
-    handleCompilerError(err, pathToElm);
+    throw compilerErrorToString(err, pathToElm);
   }
 }
 
@@ -94,13 +99,9 @@ function compile(sources, options) {
 
   try {
     return runCompiler(sources, optionsWithDefaults, pathToElm)
-      .on('error', function(err) {
-        handleError(pathToElm, err);
-
-        process.exit(1);
-      });
+      .on('error', function(err) { throw(err); });
   } catch (err) {
-    handleCompilerError(err, pathToElm);
+    throw compilerErrorToString(err, pathToElm);
   }
 }
 
@@ -123,7 +124,13 @@ function compileToString(sources, options){
       options.output = info.path;
       options.processOpts = { stdio: 'pipe' }
 
-      var compiler = compile(sources, options);
+      var compiler;
+
+      try {
+        compiler = compile(sources, options);
+      } catch(compileError) {
+        return reject(compileError);
+      }
 
       compiler.stdout.setEncoding("utf8");
       compiler.stderr.setEncoding("utf8");
@@ -163,19 +170,9 @@ function compileToStringSync(sources, options) {
   return fs.readFileSync(file.path, {encoding: "utf8"});
 }
 
-function handleError(pathToElm, err) {
-  if (err.code === "ENOENT") {
-    console.error("Could not find Elm compiler \"" + pathToElm + "\". Is it installed?")
-  } else if (err.code === "EACCES") {
-    console.error("Elm compiler \"" + pathToElm + "\" did not have permission to run. Do you need to give it executable permissions?");
-  } else {
-    console.error("Error attempting to run Elm compiler \"" + pathToElm + "\":\n" + err);
-  }
-}
-
 // Converts an object of key/value pairs to an array of arguments suitable
 // to be passed to child_process.spawn for elm-make.
-function compilerArgsFromOptions(options, emitWarning) {
+function compilerArgsFromOptions(options) {
   return _.flatten(_.map(options, function(value, opt) {
     if (value) {
       switch(opt) {

test/compile.js

@@ -34,21 +34,18 @@ describe("#compile", function() {
     });
   });
 
-  it("invokes custom `emitWarning`", function (done) {
+  it("throws when given an unrecognized argument", function () {
     var opts = {
       foo: "bar",
-      emitWarning: chai.spy(),
       output: "/dev/null",
       verbose: true,
       cwd: fixturesDir
     };
-    var compileProcess = compiler.compile(prependFixturesDir("Parent.elm"), opts);
 
-    compileProcess.on("exit", function(exitCode) {
-      var desc = "Expected emitWarning to have been called";
-      expect(opts.emitWarning, desc).to.have.been.called();
-      done();
-    });
+    expect(function() {
+      var compileProcess = compiler.compile(prependFixturesDir("Parent.elm"), opts);
+
+    }).to.throw();
   });
 });
 
@@ -98,18 +95,21 @@ describe("#compileToString", function() {
     });
   });
 
-  it("invokes custom `emitWarning`", function () {
+  it("Rejects the Promise when given an unrecognized argument like `yes`", function () {
     var opts = {
       foo: "bar",
-      emitWarning: chai.spy(),
       verbose: true,
       cwd: fixturesDir
     };
+
     var compilePromise = compiler.compileToString(prependFixturesDir("Parent.elm"), opts);
 
-    return compilePromise.then(function(err) {
-      var desc = "Expected emitWarning to have been called";
-      expect(opts.emitWarning, desc).to.have.been.called();
+    return new Promise(function(resolve, reject) {
+      return compilePromise.then(function() {
+        reject("Expected the compilation promise to be rejected due to the unrecognized compiler argument.");
+      }).catch(function() {
+        resolve();
+      });
     });
   });
 

test/compileSync.js

@@ -26,17 +26,16 @@ describe("#compileSync", function() {
     expect(exitCode, desc).to.equal(1);
   });
 
-  it("invokes custom `emitWarning`", function () {
+  it("throws when given an unrecognized argument like `yes`", function () {
     var opts = {
-      foo: "bar",
-      emitWarning: chai.spy(),
+      yes: true,
       output: "/dev/null",
       verbose: true,
       cwd: fixturesDir
     };
-    var compileProcess = compiler.compileSync(prependFixturesDir("Parent.elm"), opts);
 
-    var desc = "Expected emitWarning to have been called";
-    expect(opts.emitWarning, desc).to.have.been.called();
+    expect(function() {
+      var compileProcess = compiler.compileSync(prependFixturesDir("Parent.elm"), opts);
+    }).to.throw();
   });
 });