feat(Viewer): restore Viewer#importDefinitions

This was removed in f8f9334, but it occurred that
the method is used productively  by some of the clients.
This commit restores the method as part of public API.

Use `Viewer#importDefinitions` to import previously
parsed definitions. Now it is also possible to pass
the diagram or diagram id to be rendered during
graphical import.

lib/Viewer.js

@@ -212,9 +212,7 @@ Viewer.prototype.importXML = function(xml, bpmnDiagram, done) {
       return done(err, parseWarnings);
     }
 
-    self._setDefinitions(definitions);
-
-    self.open(bpmnDiagram, function(err, importWarnings) {
+    self.importDefinitions(definitions, bpmnDiagram, function(err, importWarnings) {
       var allWarnings = [].concat(parseWarnings, importWarnings || []);
 
       self._emit('import.done', { error: err, warnings: allWarnings });
@@ -224,6 +222,40 @@ Viewer.prototype.importXML = function(xml, bpmnDiagram, done) {
   });
 };
 
+/**
+ * Import parsed definitions and render a BPMN 2.0 diagram.
+ *
+ * Once finished the viewer reports back the result to the
+ * provided callback function with (err, warnings).
+ *
+ * ## Life-Cycle Events
+ *
+ * During import the viewer will fire life-cycle events:
+ *
+ *   * import.render.start (graphical import start)
+ *   * import.render.complete (graphical import finished)
+ *
+ * You can use these events to hook into the life-cycle.
+ *
+ * @param {ModdleElement<Definitions>} definitions parsed BPMN 2.0 definitions
+ * @param {ModdleElement<BPMNDiagram>|String} [bpmnDiagram] BPMN diagram or id of diagram to render (if not provided, the first one will be rendered)
+ * @param {Function} [done] invoked with (err, warnings=[])
+ */
+Viewer.prototype.importDefinitions = function(definitions, bpmnDiagram, done) {
+
+  if (isFunction(bpmnDiagram)) {
+    done = bpmnDiagram;
+    bpmnDiagram = null;
+  }
+
+  // done is optional
+  done = done || function() {};
+
+  this._setDefinitions(definitions);
+
+  return this.open(bpmnDiagram, done);
+};
+
 /**
  * Open diagram of previously imported XML.
  *

test/spec/ViewerSpec.js

@@ -769,6 +769,187 @@ describe('Viewer', function() {
   });
 
 
+  describe('#importDefinitions', function() {
+
+    describe('single diagram', function() {
+
+      var xml = require('../fixtures/bpmn/simple.bpmn'),
+          viewer,
+          definitions;
+
+      beforeEach(function(done) {
+        createViewer(xml, null, function(error, _, tmpViewer) {
+          if (error) {
+            return done(error);
+          }
+
+          definitions = tmpViewer.getDefinitions();
+
+          tmpViewer.destroy();
+
+          done();
+        });
+      });
+
+      beforeEach(function() {
+        viewer = new Viewer({ container: container });
+      });
+
+      afterEach(function() {
+        viewer.destroy();
+      });
+
+
+      it('should emit <import.*> events', function(done) {
+
+        // given
+        var events = [];
+
+        viewer.on([
+          'import.parse.start',
+          'import.parse.complete',
+          'import.render.start',
+          'import.render.complete',
+          'import.done'
+        ], function(e) {
+          // log event type + event arguments
+          events.push([
+            e.type,
+            Object.keys(e).filter(function(key) {
+              return key !== 'type';
+            })
+          ]);
+        });
+
+        // when
+        viewer.importDefinitions(definitions, function(err) {
+
+          // then
+          expect(events).to.eql([
+            [ 'import.render.start', [ 'definitions' ] ],
+            [ 'import.render.complete', [ 'error', 'warnings' ] ]
+          ]);
+
+          done(err);
+        });
+      });
+
+
+      it('should work without callback', function(done) {
+
+        // given
+        viewer.on('import.render.complete', function(context) {
+          // then
+          done(context.error);
+        });
+
+        // when
+        viewer.importDefinitions(definitions);
+      });
+
+    });
+
+
+    describe('multiple BPMNDiagram elements', function() {
+
+      var multipleXML = require('../fixtures/bpmn/multiple-diagrams.bpmn'),
+          viewer,
+          definitions;
+
+      beforeEach(function(done) {
+        createViewer(multipleXML, null, function(error, _, tmpViewer) {
+          if (error) {
+            return done(error);
+          }
+
+          definitions = tmpViewer.getDefinitions();
+
+          tmpViewer.destroy();
+
+          done();
+        });
+      });
+
+      beforeEach(function() {
+        viewer = new Viewer({ container: container });
+      });
+
+      afterEach(function() {
+        viewer.destroy();
+      });
+
+
+      it('should import default without bpmnDiagram specified', function(done) {
+
+        // when
+        viewer.importDefinitions(definitions, function(err) {
+
+          // then
+          done(err);
+        });
+      });
+
+
+      it('should import bpmnDiagram specified by id', function(done) {
+
+        // when
+        viewer.importDefinitions(definitions, 'BpmnDiagram_2', function(err) {
+
+          // then
+          done(err);
+        });
+      });
+
+
+      it('should handle diagram not found', function(done) {
+
+        // when
+        viewer.importDefinitions(definitions, 'Diagram_IDontExist', function(err) {
+
+          // then
+          expect(err).to.exist;
+          expect(err.message).to.eql('BPMNDiagram <Diagram_IDontExist> not found');
+
+          done();
+        });
+      });
+
+
+      describe('without callback', function() {
+
+        it('should open default', function(done) {
+
+          // given
+          viewer.on('import.render.complete', function(event) {
+
+            // then
+            done(event.error);
+          });
+
+          // when
+          viewer.importDefinitions(definitions);
+        });
+
+
+        it('should open specified BPMNDiagram', function(done) {
+
+          // given
+          viewer.on('import.render.complete', function(event) {
+
+            // then
+            done(event.error);
+          });
+
+          // when
+          viewer.importDefinitions(definitions, 'BpmnDiagram_2');
+        });
+
+      });
+
+    });
+  });
+
+
   describe('#open', function() {
 
     var multipleXMLSimple = require('../fixtures/bpmn/multiple-diagrams.bpmn'),