diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cliff-ref-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cloverleaf-ref-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/cosine_peak-ref-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/exponential-ref-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gauss-ref-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/gentle-ref-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/saddle-ref-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/sphere-ref-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/steep-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/steep-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/steep-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/steep-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/steep-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/steep-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/steep-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/steep-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/steep-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/steep-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/steep-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/steep-ref-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/trig-lin-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/trig-lin-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/trig-lin-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/trig-lin-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/trig-nn-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/trig-nn-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/trig-nn-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/trig-nn-img.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/trig-ref-con.png b/lib/matplotlib/tests/baseline_images/test_delaunay/trig-ref-con.png
diff --git a/lib/matplotlib/tests/baseline_images/test_delaunay/trig-ref-img.png b/lib/matplotlib/tests/baseline_images/test_delaunay/trig-ref-img.png
diff --git a/lib/matplotlib/tests/test_delaunay.py b/lib/matplotlib/tests/test_delaunay.py
@@ -0,0 +1,188 @@
+import numpy as np
+from matplotlib.testing.decorators import image_comparison, knownfailureif
+from matplotlib.delaunay.triangulate import Triangulation
+from matplotlib import pyplot as plt
+import matplotlib as mpl
+
+def constant(x, y):
+    return np.ones(x.shape, x.dtype)
+constant.title = 'Constant'
+
+def xramp(x, y):
+    return x
+xramp.title = 'X Ramp'
+
+def yramp(x, y):
+    return y
+yramp.title = 'Y Ramp'
+
+def exponential(x, y):
+    x = x*9
+    y = y*9
+    x1 = x+1.0
+    x2 = x-2.0
+    x4 = x-4.0
+    x7 = x-7.0
+    y1 = x+1.0
+    y2 = y-2.0
+    y3 = y-3.0
+    y7 = y-7.0
+    f = (0.75 * np.exp(-(x2*x2+y2*y2)/4.0) +
+         0.75 * np.exp(-x1*x1/49.0 - y1/10.0) +
+         0.5 * np.exp(-(x7*x7 + y3*y3)/4.0) -
+         0.2 * np.exp(-x4*x4 -y7*y7))
+    return f
+exponential.title = 'Exponential and Some Gaussians'
+
+def cliff(x, y):
+    f = np.tanh(9.0*(y-x) + 1.0)/9.0
+    return f
+cliff.title = 'Cliff'
+
+def saddle(x, y):
+    f = (1.25 + np.cos(5.4*y))/(6.0 + 6.0*(3*x-1.0)**2)
+    return f
+saddle.title = 'Saddle'
+
+def gentle(x, y):
+    f = np.exp(-5.0625*((x-0.5)**2+(y-0.5)**2))/3.0
+    return f
+gentle.title = 'Gentle Peak'
+
+def steep(x, y):
+    f = np.exp(-20.25*((x-0.5)**2+(y-0.5)**2))/3.0
+    return f
+steep.title = 'Steep Peak'
+
+def sphere(x, y):
+    circle = 64-81*((x-0.5)**2 + (y-0.5)**2)
+    f = np.where(circle >= 0, np.sqrt(np.clip(circle,0,100)) - 0.5, 0.0)
+    return f
+sphere.title = 'Sphere'
+
+def trig(x, y):
+    f = 2.0*np.cos(10.0*x)*np.sin(10.0*y) + np.sin(10.0*x*y)
+    return f
+trig.title = 'Cosines and Sines'
+
+def gauss(x, y):
+    x = 5.0-10.0*x
+    y = 5.0-10.0*y
+    g1 = np.exp(-x*x/2)
+    g2 = np.exp(-y*y/2)
+    f = g1 + 0.75*g2*(1 + g1)
+    return f
+gauss.title = 'Gaussian Peak and Gaussian Ridges'
+
+def cloverleaf(x, y):
+    ex = np.exp((10.0-20.0*x)/3.0)
+    ey = np.exp((10.0-20.0*y)/3.0)
+    logitx = 1.0/(1.0+ex)
+    logity = 1.0/(1.0+ey)
+    f = (((20.0/3.0)**3 * ex*ey)**2 * (logitx*logity)**5 *
+        (ex-2.0*logitx)*(ey-2.0*logity))
+    return f
+cloverleaf.title = 'Cloverleaf'
+
+def cosine_peak(x, y):
+    circle = np.hypot(80*x-40.0, 90*y-45.)
+    f = np.exp(-0.04*circle) * np.cos(0.15*circle)
+    return f
+cosine_peak.title = 'Cosine Peak'
+
+allfuncs = [exponential, cliff, saddle, gentle, steep, sphere, trig, gauss, cloverleaf, cosine_peak]
+
+
+class LinearTester(object):
+    name = 'Linear'
+    def __init__(self, xrange=(0.0, 1.0), yrange=(0.0, 1.0), nrange=101, npoints=250):
+        self.xrange = xrange
+        self.yrange = yrange
+        self.nrange = nrange
+        self.npoints = npoints
+
+        rng = np.random.RandomState(1234567890)
+        self.x = rng.uniform(xrange[0], xrange[1], size=npoints)
+        self.y = rng.uniform(yrange[0], yrange[1], size=npoints)
+        self.tri = Triangulation(self.x, self.y)
+
+    def replace_data(self, dataset):
+        self.x = dataset.x
+        self.y = dataset.y
+        self.tri = Triangulation(self.x, self.y)
+
+    def interpolator(self, func):
+        z = func(self.x, self.y)
+        return self.tri.linear_extrapolator(z, bbox=self.xrange+self.yrange)
+
+    def plot(self, func, interp=True, plotter='imshow'):
+        if interp:
+            lpi = self.interpolator(func)
+            z = lpi[self.yrange[0]:self.yrange[1]:complex(0,self.nrange),
+                    self.xrange[0]:self.xrange[1]:complex(0,self.nrange)]
+        else:
+            y, x = np.mgrid[self.yrange[0]:self.yrange[1]:complex(0,self.nrange),
+                            self.xrange[0]:self.xrange[1]:complex(0,self.nrange)]
+            z = func(x, y)
+
+        z = np.where(np.isinf(z), 0.0, z)
+
+        extent = (self.xrange[0], self.xrange[1],
+            self.yrange[0], self.yrange[1])
+        fig = plt.figure()
+        plt.hot() # Some like it hot
+        if plotter == 'imshow':
+            plt.imshow(np.nan_to_num(z), interpolation='nearest', extent=extent, origin='lower')
+        elif plotter == 'contour':
+            Y, X = np.ogrid[self.yrange[0]:self.yrange[1]:complex(0,self.nrange),
+                self.xrange[0]:self.xrange[1]:complex(0,self.nrange)]
+            plt.contour(np.ravel(X), np.ravel(Y), z, 20)
+        x = self.x
+        y = self.y
+        lc = mpl.collections.LineCollection(np.array([((x[i], y[i]), (x[j], y[j]))
+            for i, j in self.tri.edge_db]), colors=[(0,0,0,0.2)])
+        ax = plt.gca()
+        ax.add_collection(lc)
+
+        if interp:
+            title = '%s Interpolant' % self.name
+        else:
+            title = 'Reference'
+        if hasattr(func, 'title'):
+            plt.title('%s: %s' % (func.title, title))
+        else:
+            plt.title(title)
+
+class NNTester(LinearTester):
+    name = 'Natural Neighbors'
+    def interpolator(self, func):
+        z = func(self.x, self.y)
+        return self.tri.nn_extrapolator(z, bbox=self.xrange+self.yrange)
+
+def make_all_testfuncs(allfuncs=allfuncs):
+    def make_test(func):
+        filenames = [
+            '%s-%s' % (func.func_name, x) for x in
+            ['ref-img', 'nn-img', 'lin-img', 'ref-con', 'nn-con', 'lin-con']]
+
+        # We only generate PNGs to save disk space -- we just assume
+        # that any backend differences are caught by other tests.
+        @image_comparison(filenames, extensions=['png'])
+        def reference_test():
+            nnt.plot(func, interp=False, plotter='imshow')
+            nnt.plot(func, interp=True, plotter='imshow')
+            lpt.plot(func, interp=True, plotter='imshow')
+            nnt.plot(func, interp=False, plotter='contour')
+            nnt.plot(func, interp=True, plotter='contour')
+            lpt.plot(func, interp=True, plotter='contour')
+
+        tester = reference_test
+        tester.__name__ = 'test_%s' % func.func_name
+        return tester
+
+    nnt = NNTester(npoints=1000)
+    lpt = LinearTester(npoints=1000)
+    for func in allfuncs:
+        globals()['test_%s' % func.func_name] = make_test(func)
+
+make_all_testfuncs()