Minitest: Handle N7k F3-features w/o compat LCs (#463)

* test_vpc needs rescue for incompat intf

* Handle N7k F3-features w/o compat LCs

* The vrf_af route_target tests were failing because feature nv overlay failed - because our n7k does not have an F3 linecard:

```
 1) There are some features that refuse to load unless the VDC is
    limited to F3 only, but they will actually load if the config is
    present, despite the fact that there are no physical F3s.
 2) We have some tests that need these features but don't need interfaces.
```

* Solution: Enable the vdc config for F3 but don't fail if the physical LC is not present
  * Prior to this solution I had created a couple of methods to find an appropriate interface based on the feature-to-LC requirements. This works but is only useful for features that also require an interface (unlike the vrf_af test). Eventually I would like to remove the other one-off methods (e.g. `fabricpath_testenv_setup`, `vxlan_linecard?`, etc) that do similar functions and convert the callers to use this common one instead. Since there are no current callers for it I just commented it out.

* Tested on n7k (no F3 card) and N9K.

* /if-else/case/

lib/cisco_node_utils/cmd_ref/vdc.yaml

@@ -16,6 +16,10 @@ all_vdcs:
   get_context: ~
   get_value: '/^vdc (\S+) id/'
 
+allocate_interface:
+  get_value: '/^allocate interface (.*)/'
+  default_value: ~
+
 allocate_interface_unallocated:
   kind: boolean
   set_value: 'allocate interface unallocated-interfaces'

lib/cisco_node_utils/vdc.rb

@@ -65,6 +65,12 @@ def ==(other)
     #                      PROPERTIES                      #
     ########################################################
 
+    def allocate_interface
+      # TBD: This property is only partially implemented because it is currently
+      # only used for minitest & beaker.
+      config_get('vdc', 'allocate_interface', vdc: @vdc)
+    end
+
     def limit_resource_module_type
       str = config_get('vdc', 'limit_resource_module_type', vdc: @vdc)
       str.strip! unless str.nil?

tests/ciscotest.rb

@@ -233,6 +233,86 @@ def interface_cleanup(intf_name)
     config(*cfg)
   end
 
+  # TBD: -- The following methods are a WIP --
+  #
+  # def find_compatible_intf(feature, opt=:raise_skip)
+  #   # Some platforms require specific linecards before allowing a feature to
+  #   # be enabled. This method will find a compatible interface or optionally
+  #   # raise a skip.
+  #   # TBD: This wants to become a common "compatible interface" checker to
+  #   # eventually replace all of the single-use methods.
+  #   intf = compatible_intf(feature)
+  #   if intf.nil? && opt[/raise_skip/]
+  #     skip("Unable to find compatible interface for 'feature #{feature}'")
+  #   end
+  #   intf
+  # end
+
+  # def compatible_intf(feature)
+  #   # The feat hash contains module restrictions for a given feature.
+  #   #  :mods - (optional) The module ids used in the 'limit-resource' config
+  #   #  :pids - A regex pattern for the line module product IDs (ref: 'sh mod')
+  #   feat = {}
+  #   if node.product_id[/N7K/]
+  #     feat = {
+  #       # nv overlay raises error unless solely F3
+  #       'nv overlay' => { mods: 'f3', pids: 'N7[K7]-F3' }
+  #     }
+  #   end
+  #   patterns = feat[feature]
+  #   return interfaces[0] if patterns.nil? #  No restrictions for this platform
+
+  #   # Check if module is present and usable; i.e. 'ok'
+  #   pids = patterns[:pids]
+  #   sh_mod_string = @device.cmd("show mod | i '^[0-9]+.*#{pids}.*ok'")
+  #   sh_mod = sh_mod_string[/^(\d+)\s.*#{pids}/]
+  #   slot = sh_mod.nil? ? nil : Regexp.last_match[1]
+  #   return nil if slot.nil?
+  #   intf = "ethernet#{slot}/1"
+
+  #   # Check/Set VDC config. VDC platforms restrict module usage per vdc.
+  #   mods = patterns[:mods]
+  #   return intf if mods.nil? || !node.product_id[/N7K/]
+  #   vdc = Vdc.new(Vdc.default_vdc_name)
+  #   unless mods == vdc.limit_resource_module_type
+  #     # Update the allowed module types in this vdc
+  #     vdc.limit_resource_module_type = mods
+  #   end
+
+  #   # Return the first interface found in 'allocate interface' config, or nil
+  #   vdc.allocate_interface[%r{Ethernet#{slot}\/(\d+)}]
+  # end
+
+  def vdc_limit_f3_no_intf_needed(action=:set)
+    # This is a special-use method for N7Ks that don't have a physical F3.
+    #  1) There are some features that refuse to load unless the VDC is
+    #     limited to F3 only, but they will actually load if the config is
+    #     present, despite the fact that there are no physical F3s.
+    #  2) We have some tests that need these features but don't need interfaces.
+    #
+    # action = :set (enable limit F3 config), :clear (default limit config)
+    #
+    # The limit config should be removed after testing if the device does not
+    # have an actual F3.
+    return unless node.product_id[/N7K/]
+    vdc = Vdc.new(Vdc.default_vdc_name)
+    case action
+    when :set
+      return if vdc.limit_resource_module_type == 'f3'
+      vdc.limit_resource_module_type = 'f3'
+
+    when :clear
+      # Remove the config if there are no physical F3 cards
+      pids = 'N7[K7]-F3'
+      sh_mod_string = @device.cmd("show mod | i '^[0-9]+.*#{pids}'")
+      sh_mod = sh_mod_string[/^(\d+)\s.*#{pids}/]
+      if sh_mod.nil?
+        # It's safe to remove the config
+        vdc.limit_resource_module_type = ''
+      end
+    end
+  end
+
   # setup fabricpath env if possible and populate the interfaces array
   # otherwise cause a global skip
   def fabricpath_testenv_setup

tests/test_vrf_af.rb

@@ -111,15 +111,12 @@ def route_policy(af)
   end
 
   def test_route_target
+    vdc_limit_f3_no_intf_needed(:set)
     [%w(ipv4 unicast), %w(ipv6 unicast)].each { |af| route_target(af) }
+    vdc_limit_f3_no_intf_needed(:clear)
   end
 
   def route_target(af)
-    #
-    # TBD: The evpn parts of this test need to check for compatible linecards to
-    # skip the evpn portions. Don't use vxlan_linecard? as that will cause all
-    # tests to be skipped.
-    #
     # Common tester for route-target properties. Tests evpn and non-evpn.
     #   route_target_both_auto
     #   route_target_both_auto_evpn