Test cases for systemd-networkd

[haraldh]

Would be cool to introduce the test cases like for NM:

test/TEST-21-NFS-NM/Makefile
test/TEST-31-ISCSI-NM/Makefile
test/TEST-36-ISCSI-MULTI-NM/Makefile
test/TEST-41-NBD-NM/Makefile
test/TEST-51-MULTINIC-NM/Makefile
test/TEST-61-BONDBRIDGEVLANIFCFG-NM/Makefile

with networkd... relevant code changes:

diff --git a/test/TEST-20-NFS/test.sh b/test/TEST-20-NFS/test.sh
index 5a46f3d5..868f62b8 100755
--- a/test/TEST-20-NFS/test.sh
+++ b/test/TEST-20-NFS/test.sh
@@ -2,10 +2,13 @@
 
 if [[ $NM ]]; then
     USE_NETWORK="network-manager"
-    OMIT_NETWORK="network-legacy"
+    OMIT_NETWORK="network-legacy systemd-networkd"
+elif [[ $SNWD ]]; then
+    USE_NETWORK="systemd-networkd"
+    OMIT_NETWORK="network-legacy network-manager"
 else
     USE_NETWORK="network-legacy"
-    OMIT_NETWORK="network-manager"
+    OMIT_NETWORK="network-manager systemd-networkd"
 fi

also for

test/TEST-30-ISCSI/test.sh
test/TEST-35-ISCSI-MULTI/test.sh
test/TEST-40-NBD/test.sh
test/TEST-50-MULTINIC/test.sh
test/TEST-60-BONDBRIDGEVLANIFCFG/test.sh

Maybe refactor things into test/test-functions

Originally posted by @haraldh in #1348 (comment)

[stale]

This issue is being marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. If this is still an issue in the latest release of Dracut and you would like to keep it open please comment on this issue within the next 7 days. Thank you for your contributions.

[LaszloGombos]

Related - #2089

[LaszloGombos]

Related - #2117

[LaszloGombos]

Testing now possible but many tests are failing - #2141