sankey: arangement defaults to freeform if node.(x|y) is specified

Author: antoinerg

src/traces/sankey/defaults.js

@@ -84,7 +84,12 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     coerce('orientation');
     coerce('valueformat');
     coerce('valuesuffix');
-    coerce('arrangement');
+
+    var dfltArrangement;
+    if(nodeOut.x.length && nodeOut.y.length) {
+        dfltArrangement = 'freeform';
+    }
+    coerce('arrangement', dfltArrangement);
 
     Lib.coerceFont(coerce, 'textfont', Lib.extendFlat({}, layout.font));
 

test/jasmine/tests/sankey_test.js

@@ -250,6 +250,32 @@ describe('sankey tests', function() {
             expect(Array.isArray(fullTrace.link.label)).toBe(true, 'must be an array');
             expect(fullTrace.link.label).toEqual(['a', 'b'], 'an array of the supplied values');
         });
+
+        it('defaults to `snap` arrangement', function() {
+            var fullTrace = _supply({
+                link: {
+                    source: [0],
+                    target: [1],
+                    value: [1]
+                }
+            });
+            expect(fullTrace.arrangement).toBe('snap');
+        });
+
+        it('defaults to `freeform` arrangement if node.(x|y) is specified', function() {
+            var fullTrace = _supply({
+                node: {
+                    x: [0, 0.5],
+                    y: [0, 0.5]
+                },
+                link: {
+                    source: [0],
+                    target: [1],
+                    value: [1]
+                }
+            });
+            expect(fullTrace.arrangement).toBe('freeform');
+        });
     });
 
     describe('sankey calc', function() {