make test: improve documentation and PEP8 compliance

Change-Id: Ib4f0353aab6112fcc3c3d8f0bcbed5bc4b567b9b
Signed-off-by: Klement Sekera <ksekera@cisco.com>

1 files changed, 276 insertions, 9 deletions

diff --git a/test/doc/index.rst b/test/doc/index.rst
index 8cbe961f..f51d5058 100644
--- a/test/doc/index.rst
+++ b/test/doc/index.rst
@@ -4,6 +4,7 @@
 .. _SkipTest: https://docs.python.org/2/library/unittest.html#unittest.SkipTest
 .. _virtualenv: http://docs.python-guide.org/en/latest/dev/virtualenvs/
 .. _scapy: http://www.secdev.org/projects/scapy/
+.. _logging: https://docs.python.org/2/library/logging.html
 
 .. |vtf| replace:: VPP Test Framework
 
@@ -39,7 +40,7 @@ Function flow when running a test case is:
 3. *test_<name>*:
    This is the guts of the test case. It should execute the test scenario
    and use the various assert functions from the unittest framework to check
-   necessary.
+   necessary. Multiple test_<name> methods can exist in a test case.
 4. `tearDown <VppTestCase.tearDown>`:
    The tearDown function is called after each test function with the purpose
    of doing partial cleanup.
@@ -47,16 +48,56 @@ Function flow when running a test case is:
    Method called once after running all of the test functions to perform
    the final cleanup.
 
+Logging
+#######
+
+Each test case has a logger automatically created for it, stored in
+'logger' property, based on logging_. Use the logger's standard methods
+debug(), info(), error(), ... to emit log messages to the logger.
+
+All the log messages go always into a log file in temporary directory
+(see below).
+
+To control the messages printed to console, specify the V= parameter.
+
+.. code-block:: shell
+
+   make test         # minimum verbosity
+   make test V=1     # moderate verbosity
+   make test V=2     # maximum verbosity
+
 Test temporary directory and VPP life cycle
 ###########################################
 
 Test separation is achieved by separating the test files and vpp instances.
 Each test creates a temporary directory and it's name is used to create
 a shared memory prefix which is used to run a VPP instance.
+The temporary directory name contains the testcase class name for easy
+reference, so for testcase named 'TestVxlan' the directory could be named
+e.g. vpp-unittest-TestVxlan-UNUP3j.
 This way, there is no conflict between any other VPP instances running
 on the box and the test VPP. Any temporary files created by the test case
 are stored in this temporary test directory.
 
+The test temporary directory holds the following interesting files:
+
+* log.txt - this contains the logger output on max verbosity
+* pg*_in.pcap - last injected packet stream into VPP, named after the interface,
+  so for pg0, the file will be named pg0_in.pcap
+* pg*_out.pcap - last capture file created by VPP for interface, similarly,
+  named after the interface, so for e.g. pg1, the file will be named
+  pg1_out.pcap
+* history files - whenever the capture is restarted or a new stream is added,
+  the existing files are rotated and renamed, soo all the pcap files
+  are always saved for later debugging if needed
+* core - if vpp dumps a core, it'll be stored in the temporary directory
+* vpp_stdout.txt - file containing output which vpp printed to stdout
+* vpp_stderr.txt - file containing output which vpp printed to stderr
+
+*NOTE*: existing temporary directories named vpp-unittest-* are automatically
+removed when invoking 'make test*' or 'make retest*' to keep the temporary
+directory clean.
+
 Virtual environment
 ###################
 
@@ -82,6 +123,37 @@ thus:
   So e.g. `remote_mac <VppInterface.remote_mac>` address is the MAC address
   assigned to the virtual host connected to the VPP.
 
+Automatically generated addresses
+#################################
+
+To send packets, one needs to typically provide some addresses, otherwise
+the packets will be dropped. The interface objects in |vtf| automatically
+provide addresses based on (typically) their indexes, which ensures
+there are no conflicts and eases debugging by making the addressing scheme
+consistent.
+
+The developer of a test case typically doesn't need to work with the actual
+numbers, rather using the properties of the objects. The addresses typically
+come in two flavors: '<address>' and '<address>n' - note the 'n' suffix.
+The former address is a Python string, while the latter is translated using
+socket.inet_pton to raw format in network byte order - this format is suitable
+for passing as an argument to VPP APIs.
+
+e.g. for the IPv4 address assigned to the VPP interface:
+
+* local_ip4 - Local IPv4 address on VPP interface (string)
+* local_ip4n - Local IPv4 address - raw, suitable as API parameter.
+
+These addresses need to be configured in VPP to be usable using e.g.
+`config_ip4` API. Please see the documentation to `VppInterface` for more
+details.
+
+By default, there is one remote address of each kind created for L3:
+remote_ip4 and remote_ip6. If the test needs more addresses, because it's
+simulating more remote hosts, they can be generated using
+`generate_remote_hosts` API and the entries for them inserted into the ARP
+table using `configure_ipv4_neighbors` API.
+
 Packet flow in the |vtf|
 ########################
 
@@ -93,6 +165,10 @@ using packet-generator interfaces, represented by the `VppPGInterface` class.
 Packets are written into a temporary .pcap file, which is then read by the VPP
 and the packets are injected into the VPP world.
 
+To add a list of packets to an interface, call the `add_stream` method on that
+interface. Once everything is prepared, call `pg_start` method to start
+the packet generator on the VPP side.
+
 VPP -> test framework
 ~~~~~~~~~~~~~~~~~~~~~
 
@@ -100,6 +176,72 @@ Similarly, VPP doesn't send any packets to |vtf| directly. Instead, packet
 capture feature is used to capture and write traffic to a temporary .pcap file,
 which is then read and analyzed by the |vtf|.
 
+The following APIs are available to the test case for reading pcap files.
+
+* `get_capture`: this API is suitable for bulk & batch style of test, where
+  a list of packets is prepared & sent, then the received packets are read
+  and verified. The API needs the number of packets which are expected to
+  be captured (ignoring filtered packets - see below) to know when the pcap
+  file is completely written by the VPP. If using packet infos for verifying
+  packets, then the counts of the packet infos can be automatically used
+  by `get_capture` to get the proper count (in this case the default value
+  None can be supplied as expected_count or ommitted altogether).
+* `wait_for_packet`: this API is suitable for interactive style of test,
+  e.g. when doing session management, three-way handsakes, etc. This API waits
+  for and returns a single packet, keeping the capture file in place
+  and remembering context. Repeated invocations return following packets
+  (or raise Exception if timeout is reached) from the same capture file
+  (= packets arriving on the same interface).
+
+*NOTE*: it is not recommended to mix these APIs unless you understand how they
+work internally. None of these APIs rotate the pcap capture file, so calling
+e.g. `get_capture` after `wait_for_packet` will return already read packets.
+It is safe to switch from one API to another after calling `enable_capture`
+as that API rotates the capture file.
+
+Automatic filtering of packets:
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Both APIs (`get_capture` and `wait_for_packet`) by default filter the packet
+capture, removing known uninteresting packets from it - these are IPv6 Router
+Advertisments and IPv6 Router Alerts. These packets are unsolicitated
+and from the point of |vtf| are random. If a test wants to receive these
+packets, it should specify either None or a custom filtering function
+as the value to the 'filter_out_fn' argument.
+
+Common API flow for sending/receiving packets:
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+We will describe a simple scenario, where packets are sent from pg0 to pg1
+interface, assuming that the interfaces were created using
+`create_pg_interfaces` API.
+
+1. Create a list of packets for pg0::
+
+     packet_count = 10
+     packets = create_packets(src=self.pg0, dst=self.pg1,
+                              count=packet_count)
+
+2. Add that list of packets to the source interface::
+
+     self.pg0.add_stream(packets)
+
+3. Enable capture on the destination interface::
+
+     self.pg1.enable_capture()
+
+4. Start the packet generator::
+
+     self.pg_start()
+
+5. Wait for capture file to appear and read it::
+
+     capture = self.pg1.get_capture(expected_count=packet_count)
+
+6. Verify packets match sent packets::
+
+     self.verify_capture(send=packets, captured=capture)
+
 Test framework objects
 ######################
 
@@ -113,8 +255,8 @@ common tasks easily in the test cases.
 * `VppSubInterface`: VPP sub-interface abstract class, containing common
   functionality for e.g. `VppDot1QSubint` and `VppDot1ADSubint` classes
 
-How VPP API/CLI is called
-#########################
+How VPP APIs/CLIs are called
+############################
 
 Vpp provides python bindings in a python module called vpp-papi, which the test
 framework installs in the virtual environment. A shim layer represented by
@@ -137,19 +279,144 @@ purposes:
    more readable. E.g. ip_add_del_route API takes ~25 parameters, of which
    in the common case, only 3 are needed.
 
+Utility methods
+###############
+
+Some interesting utility methods are:
+
+* `ppp`: 'Pretty Print Packet' - returns a string containing the same output
+  as Scapy's packet.show() would print
+* `ppc`: 'Pretty Print Capture' - returns a string containing printout of
+  a capture (with configurable limit on the number of packets printed from it)
+  using `ppp`
+
+*NOTE*: Do not use Scapy's packet.show() in the tests, because it prints
+the output to stdout. All output should go to the logger associated with
+the test case.
+
 Example: how to add a new test
 ##############################
 
-In this example, we will describe how to add a new test case which tests VPP...
+In this example, we will describe how to add a new test case which tests
+basic IPv4 forwarding.
+
+1. Add a new file called test_ip4_fwd.py in the test directory, starting
+   with a few imports::
+
+     from framework import VppTestCase
+     from scapy.layers.l2 import Ether
+     from scapy.packet import Raw
+     from scapy.layers.inet import IP, UDP
+     from random import randint
+
+2. Create a class inherited from the VppTestCase::
+
+     class IP4FwdTestCase(VppTestCase):
+         """ IPv4 simple forwarding test case """
+
+2. Add a setUpClass function containing the setup needed for our test to run::
+
+         @classmethod
+         def setUpClass(self):
+             super(IP4FwdTestCase, self).setUpClass()
+             self.create_pg_interfaces(range(2))  #  create pg0 and pg1
+             for i in self.pg_interfaces:
+                 i.admin_up()  # put the interface up
+                 i.config_ip4()  # configure IPv4 address on the interface
+                 i.resolve_arp()  # resolve ARP, so that we know VPP MAC
+
+3. Create a helper method to create the packets to send::
+
+         def create_stream(self, src_if, dst_if, count):
+             packets = []
+             for i in range(count):
+                 # create packet info stored in the test case instance
+                 info = self.create_packet_info(src_if, dst_if)
+                 # convert the info into packet payload
+                 payload = self.info_to_payload(info)
+                 # create the packet itself
+                 p = (Ether(dst=src_if.local_mac, src=src_if.remote_mac) /
+                      IP(src=src_if.remote_ip4, dst=dst_if.remote_ip4) /
+                      UDP(sport=randint(1000, 2000), dport=5678) /
+                      Raw(payload))
+                 # store a copy of the packet in the packet info
+                 info.data = p.copy()
+                 # append the packet to the list
+                 packets.append(p)
+
+             # return the created packet list
+             return packets
+
+4. Create a helper method to verify the capture::
+
+         def verify_capture(self, src_if, dst_if, capture):
+             packet_info = None
+             for packet in capture:
+                 try:
+                     ip = packet[IP]
+                     udp = packet[UDP]
+                     # convert the payload to packet info object
+                     payload_info = self.payload_to_info(str(packet[Raw]))
+                     # make sure the indexes match
+                     self.assert_equal(payload_info.src, src_if.sw_if_index,
+                                       "source sw_if_index")
+                     self.assert_equal(payload_info.dst, dst_if.sw_if_index,
+                                       "destination sw_if_index")
+                     packet_info = self.get_next_packet_info_for_interface2(
+                                       src_if.sw_if_index,
+                                       dst_if.sw_if_index,
+                                       packet_info)
+                     # make sure we didn't run out of saved packets
+                     self.assertIsNotNone(packet_info)
+                     self.assert_equal(payload_info.index, packet_info.index,
+                                       "packet info index")
+                     saved_packet = packet_info.data  # fetch the saved packet
+                     # assert the values match
+                     self.assert_equal(ip.src, saved_packet[IP].src,
+                                       "IP source address")
+                     # ... more assertions here
+                     self.assert_equal(udp.sport, saved_packet[UDP].sport,
+                                       "UDP source port")
+                 except:
+                     self.logger.error(ppp("Unexpected or invalid packet:",
+                                       packet))
+                     raise
+             remaining_packet = self.get_next_packet_info_for_interface2(
+                        src_if.sw_if_index,
+                        dst_if.sw_if_index,
+                        packet_info)
+             self.assertIsNone(remaining_packet,
+                               "Interface %s: Packet expected from interface "
+                               "%s didn't arrive" % (dst_if.name, src_if.name))
+
+5. Add the test code to test_basic function::
+
+         def test_basic(self):
+             count = 10
+             # create the packet stream
+             packets = self.create_stream(self.pg0, self.pg1, count)
+             # add the stream to the source interface
+             self.pg0.add_stream(packets)
+             # enable capture on both interfaces
+             self.pg0.enable_capture()
+             self.pg1.enable_capture()
+             # start the packet generator
+             self.pg_start()
+             # get capture - the proper count of packets was saved by
+             # create_packet_info() based on dst_if parameter
+             capture = self.pg1.get_capture()
+             # assert nothing captured on pg0 (always do this last, so that
+             # some time has already passed since pg_start())
+             self.pg0.assert_nothing_captured()
+             # verify capture
+             self.verify_capture(self.pg0, self.pg1, capture)
+
+6. Run the test by issuing 'make test'.
 
-1. Add a new file called...
-2. Add a setUpClass function containing...
-3. Add the test code in test...
-4. Run the test...
 
 |vtf| module documentation
 ##########################
- 
+
 .. toctree::
    :maxdepth: 2
    :glob: