Add test_setData() for PlotDataItem class

pyqtgraph/graphicsItems/tests/test_PlotDataItem.py

@@ -23,3 +23,29 @@ def test_fft():
     x, y = pd.getData()
     assert abs(x[np.argmax(y)] - np.log10(f)) < 0.01
 
+def test_setData():
+    pdi = pg.PlotDataItem()
+
+    #test empty data
+    pdi.setData([])
+
+    #test y data
+    y = list(np.random.normal(size=100))
+    pdi.setData(y)
+    assert len(pdi.xData) == 100
+    assert len(pdi.yData) == 100
+
+    #test x, y data
+    y += list(np.random.normal(size=50))
+    x = np.linspace(5, 10, 150)
+
+    pdi.setData(x, y)
+    assert len(pdi.xData) == 150
+    assert len(pdi.yData) == 150
+
+    #test dict of x, y list
+    y += list(np.random.normal(size=50))
+    x = list(np.linspace(5, 10, 200))
+    pdi.setData({'x': x, 'y': y})
+    assert len(pdi.xData) == 200
+    assert len(pdi.yData) == 200