test: Improve unit tests to verify basic functionality

Also a more complete ping test that parses all output to the CLI.

These tests expand the hifi-specific ones to not just cover whether
a topology can be created with options, but whether those options
are properly implemented within some tolerance, like CPU limits,
link bandwidth, delays, and even drops.

mininet/test/test_hifi.py

@@ -7,6 +7,8 @@ import unittest
 
 from mininet.net import Mininet
 from mininet.node import OVSKernelSwitch
+from mininet.node import CPULimitedHost
+from mininet.link import TCLink
 from mininet.topo import Topo
 from mininet.log import setLogLevel
 
@@ -18,7 +20,11 @@ N = 2
 
 class SingleSwitchOptionsTopo(Topo):
     "Single switch connected to n hosts."
-    def __init__(self, n=2, hopts={}, lopts={}):
+    def __init__(self, n=2, hopts=None, lopts=None):
+        if not hopts:
+            hopts = {}
+        if not lopts:
+            lopts = {}
         Topo.__init__(self, hopts=hopts, lopts=lopts)
         switch = self.addSwitch('s1')
         for h in range(n):
@@ -31,31 +37,89 @@ class testOptionsTopo( unittest.TestCase ):
 
     def runOptionsTopoTest( self, n, hopts=None, lopts=None ):
         "Generic topology-with-options test runner."
-        mn = Mininet( SingleSwitchOptionsTopo( n=n, hopts=hopts ) )
+        mn = Mininet( topo=SingleSwitchOptionsTopo( n=n, hopts=hopts,
+                                                    lopts=lopts ),
+                      host=CPULimitedHost, link=TCLink )
         dropped = mn.run( mn.ping )
         self.assertEqual( dropped, 0 )
 
+    def assertWithinTolerance(self, measured, expected, tolerance_frac):
+        """Check that a given value is within a tolerance of expected
+        tolerance_frac: less-than-1.0 value; 0.8 would yield 20% tolerance.
+        """
+        self.assertTrue( float(measured) >= float(expected) * tolerance_frac )
+        self.assertTrue( float(measured) >= float(expected) * tolerance_frac )
+
     def testCPULimits( self ):
-        hopts = { 'cpu': 0.5 / N }
-        self.runOptionsTopoTest(N, hopts=hopts)
+        "Verify topology creation with CPU limits set for both schedulers."
+        CPU_FRACTION = 0.1
+        CPU_TOLERANCE = 0.8  # CPU fraction below which test should fail
+        hopts = { 'cpu': CPU_FRACTION }
+        #self.runOptionsTopoTest( N, hopts=hopts )
+
+        mn = Mininet( SingleSwitchOptionsTopo( n=N, hopts=hopts ),
+                      host=CPULimitedHost )
+        mn.start()
+        results = mn.runCpuLimitTest( cpu=CPU_FRACTION )
+        mn.stop()
+        for cpu in results:
+            self.assertWithinTolerance( cpu, CPU_FRACTION, CPU_TOLERANCE )
 
     def testLinkBandwidth( self ):
-        lopts = { 'bw': 10, 'use_htb': True }
-        self.runOptionsTopoTest(N, lopts=lopts)
+        "Verify that link bandwidths are accurate within a bound."
+        BW = 5  # Mbps
+        BW_TOLERANCE = 0.8  # BW fraction below which test should fail
+        # Verify ability to create limited-link topo first;
+        lopts = { 'bw': BW, 'use_htb': True }
+        # Also verify correctness of limit limitng within a bound.
+        mn = Mininet( SingleSwitchOptionsTopo( n=N, lopts=lopts ),
+                      link=TCLink )
+        bw_strs = mn.run( mn.iperf )
+        for bw_str in bw_strs:
+            bw = float( bw_str.split(' ')[0] )
+            self.assertWithinTolerance( bw, BW, BW_TOLERANCE )
 
     def testLinkDelay( self ):
-        lopts = { 'delay': '5ms', 'use_htb': True }
-        self.runOptionsTopoTest(N, lopts=lopts)
+        "Verify that link delays are accurate within a bound."
+        DELAY_MS = 15
+        DELAY_TOLERANCE = 0.8  # Delay fraction below which test should fail
+        lopts = { 'delay': '%sms' % DELAY_MS, 'use_htb': True }
+        mn = Mininet( SingleSwitchOptionsTopo( n=N, lopts=lopts ),
+                      link=TCLink )
+        ping_delays = mn.run( mn.pingFull )
+        test_outputs = ping_delays[0]
+        # Ignore unused variables below
+        # pylint: disable-msg=W0612
+        node, dest, ping_outputs = test_outputs
+        sent, received, rttmin, rttavg, rttmax, rttdev = ping_outputs
+        self.assertEqual( sent, received )
+        # pylint: enable-msg=W0612
+        for rttval in [rttmin, rttavg, rttmax]:
+            # Multiply delay by 4 to cover there & back on two links
+            self.assertWithinTolerance( rttval, DELAY_MS * 4.0,
+                                        DELAY_TOLERANCE)
 
     def testLinkLoss( self ):
-        lopts = { 'loss': 10, 'use_htb': True }
-        self.runOptionsTopoTest(N, lopts=lopts)
+        "Verify that we see packet drops with a high configured loss rate."
+        LOSS_PERCENT = 99
+        REPS = 1
+        lopts = { 'loss': LOSS_PERCENT, 'use_htb': True }
+        mn = Mininet( topo=SingleSwitchOptionsTopo( n=N, lopts=lopts ),
+                      host=CPULimitedHost, link=TCLink )
+        # Drops are probabilistic, but the chance of no dropped packets is
+        # 1 in 100 million with 4 hops for a link w/99% loss.
+        dropped_total = 0
+        mn.start()
+        for _ in range(REPS):
+            dropped_total += mn.ping(timeout='1')
+        mn.stop()
+        self.assertTrue(dropped_total > 0)
 
-    def testAllOptions( self ):
-        lopts = { 'bw': 10, 'delay': '5ms', 'loss': 10, 'use_htb': True }
+    def testMostOptions( self ):
+        "Verify topology creation with most link options and CPU limits."
+        lopts = { 'bw': 10, 'delay': '5ms', 'use_htb': True }
         hopts = { 'cpu': 0.5 / N }
-        self.runOptionsTopoTest(N, hopts=hopts, lopts=lopts)
-
+        self.runOptionsTopoTest( N, hopts=hopts, lopts=lopts )
 
 
 if __name__ == '__main__':