Skip duplicate configurations.

This should resolve #289.

This also detects a bad configuration where multiple blocks attempt to write
to the same destination with different sources.

Author: Aaron Boushley

lib/configwriter.js

@@ -49,6 +49,7 @@ var ConfigWriter = module.exports = function (flow, dirs) {
   this.staging = dirs.staging;
   this.steps = {};
   this.postprocessors = [];
+  this.destinations = {};
 
   // We need to create all the needed config writers, given them their output directory
   // E.g, if we do have the flow concat | uglifyjs, the output dir will be .tmp/concat and dist
@@ -158,6 +159,9 @@ ConfigWriter.prototype.process = function (file, config) {
     }
 
     self.forEachStep(block.type, function (writer, last) {
+      var blockConfig;
+      var fileSet;
+      var dest;
 
       // If this is the last writer of the pipe, we need to output
       // in the destination directory
@@ -167,7 +171,26 @@ ConfigWriter.prototype.process = function (file, config) {
       config[writer.name].generated = config[writer.name].generated || {};
       context.options = config[writer.name];
       // config[writer.name].generated = _.extend(config[writer.name].generated, writer.createConfig(context, block));
-      config[writer.name].generated = deepMerge(config[writer.name].generated, writer.createConfig(context, block));
+      blockConfig = writer.createConfig(context, block);
+      if (blockConfig.files) {
+        fileSet = blockConfig.files;
+        blockConfig.files = [];
+        fileSet.forEach(function (filesInfo) {
+          dest = filesInfo.dest;
+          if (!self.destinations[dest]) {
+            self.destinations[dest] = filesInfo;
+            blockConfig.files.push(filesInfo);
+          } else if (!_.isEqual(self.destinations[dest], filesInfo)) {
+            throw new Error('Different sources attempting to write to the same destination:\n ' + JSON.stringify(self.destinations[dest], null, '    ') + '\n  ' + JSON.stringify(blockConfig, null, '    '));
+          }
+        });
+
+        if (blockConfig.files.length) {
+          config[writer.name].generated = deepMerge(config[writer.name].generated, blockConfig);
+        }
+      } else {
+        config[writer.name].generated = deepMerge(config[writer.name].generated, blockConfig);
+      }
       context.inDir = context.outDir;
       context.inFiles = context.outFiles;
       context.outFiles = [];

test/test-config-writer.js

@@ -266,6 +266,122 @@ describe('ConfigWriter', function () {
     it('should allow for an empty flow');
     it('should allow for a filename as input');
 
+    it('should deduplicate blocks', function () {
+      var flow = new Flow({
+        steps: {
+          js: ['concat', 'uglifyjs']
+        }
+      });
+      var doubleBlocks = [blocks[0], blocks[0]];
+      var file = helpers.createFile('foo', 'app', doubleBlocks);
+      var c = new ConfigWriter(flow, {
+        input: 'app',
+        dest: 'dist',
+        staging: '.tmp'
+      });
+      var config = c.process(file);
+      var expected = helpers.normalize({
+        concat: {
+          generated: {
+            files: [{
+              dest: '.tmp/concat/scripts/site.js',
+              src: ['app/foo.js', 'app/bar.js', 'app/baz.js']
+            }]
+          }
+        },
+        uglify: {
+          generated: {
+            files: [{
+              dest: 'dist/scripts/site.js',
+              src: ['.tmp/concat/scripts/site.js']
+            }]
+          }
+        }
+      });
+
+      assert.deepEqual(config, expected);
+    });
+    it('should deduplicate blocks across files', function () {
+      var flow = new Flow({
+        steps: {
+          js: ['concat', 'uglifyjs']
+        }
+      });
+      var file = helpers.createFile('foo', 'app', blocks);
+      var c = new ConfigWriter(flow, {
+        input: 'app',
+        dest: 'dist',
+        staging: '.tmp'
+      });
+      var firstConfig = c.process(file);
+      var repeatConfig = c.process(file);
+      var expectedFirst = helpers.normalize({
+        concat: {
+          generated: {
+            files: [{
+              dest: '.tmp/concat/scripts/site.js',
+              src: ['app/foo.js', 'app/bar.js', 'app/baz.js']
+            }]
+          }
+        },
+        uglify: {
+          generated: {
+            files: [{
+              dest: 'dist/scripts/site.js',
+              src: ['.tmp/concat/scripts/site.js']
+            }]
+          }
+        }
+      });
+      var expectedRepeat = helpers.normalize({
+        concat: {
+          generated: {}
+        },
+        uglify: {
+          generated: {}
+        }
+      });
+
+      assert.deepEqual(firstConfig, expectedFirst);
+      assert.deepEqual(repeatConfig, expectedRepeat);
+    });
+    it('should throw with conflicting blocks', function () {
+      var flow = new Flow({
+        steps: {
+          js: ['concat', 'uglifyjs']
+        }
+      });
+      var conflictBlock = {
+        type: 'js',
+        dest: 'scripts/site.js',
+        searchPath: [],
+        indent: '    ',
+        src: [
+          'foo.js',
+          'bar.js',
+          'baz.js',
+          'fail.js'
+        ],
+        raw: [
+          '    <!-- build:js scripts/site.js -->',
+          '    <script src="foo.js"></script>',
+          '    <script src="bar.js"></script>',
+          '    <script src="baz.js"></script>',
+          '    <script src="fail.js"></script>',
+          '    <!-- endbuild -->'
+        ]
+      };
+      var file = helpers.createFile('foo', 'app', [blocks[0], conflictBlock]);
+      var c = new ConfigWriter(flow, {
+        input: 'app',
+        dest: 'dist',
+        staging: '.tmp'
+      });
+      assert.throws(function () {
+        c.process(file);
+      });
+    });
+
     describe('stepWriters', function () {
       it('should return all writers if called without block type', function () {
         var flow = new Flow({