test: improvements and fixes

[evilrobot-01]

Some improvements and fixes whilst reviewing #240.

See commit log for further details.

PS - sincere apologies about the last two commits, which were triggered by the fact that this PR tree has not been rebased on main. Rather than reformatting everything, to reformat again in the coming days, I think it made sense to bring in the nightly formatting and apply the fixes accordingly. We would have to tackle it imminently in any case. You should be able to select a range of commits when reviewing to exclude the last two.

[peterwht]

Nice clean commits.

[chungquantin]

Looks clean overall, left a few comments for my concerns.

[chungquantin]

LGTM!

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 89.78328% with 33 lines in your changes missing coverage. Please review.

Project coverage is 45.24%. Comparing base (e36c833) to head (1bd5060).

Files with missing lines	Patch %	Lines
extension/src/functions.rs	93.75%	0 Missing and 7 partials ⚠️
pallets/api/src/extension.rs	0.00%	6 Missing ⚠️
primitives/src/lib.rs	0.00%	6 Missing ⚠️
extension/src/tests.rs	92.06%	0 Missing and 5 partials ⚠️
extension/src/lib.rs	96.38%	0 Missing and 3 partials ⚠️
node/src/command.rs	0.00%	2 Missing ⚠️
runtime/devnet/src/config/xcm.rs	0.00%	2 Missing ⚠️
runtime/testnet/src/config/xcm.rs	0.00%	2 Missing ⚠️

@@                       Coverage Diff                        @@
##           chungquantin/extension-tests     #262      +/-   ##
================================================================
+ Coverage                         41.83%   45.24%   +3.40%     
================================================================
  Files                                39       40       +1     
  Lines                              3468     3698     +230     
  Branches                           3468     3698     +230     
================================================================
+ Hits                               1451     1673     +222     
- Misses                             1969     1971       +2     
- Partials                             48       54       +6     

Files with missing lines	Coverage Δ
extension/src/decoding.rs	96.95% <100.00%> (-0.48%)	⬇️
extension/src/matching.rs	100.00% <100.00%> (ø)
extension/src/mock.rs	95.12% <100.00%> (+0.03%)	⬆️
pallets/api/src/fungibles/mod.rs	82.96% <100.00%> (ø)
runtime/devnet/src/config/api/mod.rs	0.00% <ø> (ø)
runtime/devnet/src/config/api/versioning.rs	61.19% <100.00%> (+0.29%)	⬆️
runtime/devnet/src/config/proxy.rs	0.00% <ø> (ø)
runtime/devnet/src/lib.rs	17.31% <ø> (ø)
runtime/testnet/src/config/proxy.rs	0.00% <ø> (ø)
runtime/testnet/src/extensions.rs	0.00% <ø> (ø)
... and 9 more