Check if feed pair exists while adding asset in pallet asset index

[clearloop]

Issue summary

The call add_asset in pallet asset-index adds assets directly without checking if the matched feed pair exists which make the following calls like deposit could not execute

Other information and links

• AssetPriceFeed not found in the call deposit of pallet asset-index #93

• PINT/pallets/price-feed/src/tests.rs

  Line 90 in 4fcfc4f

  fn price_pair_should_be_available() {

[mattsse]

The add_asset is an admin/council only function which mints the given amount of PINT token.

The asset/pint rate is essentially determined by the admin here. We could probably use this initial rate until a price feed exists for this asset?

[clearloop]

The add_asset is an admin/council only function which mints the given amount of PINT token.

Understand this design, except the price feed probem, the other problem is, with EnsureRoot in our runtime configuration,

• PINT/runtime/src/lib.rs

  Line 540 in 4fcfc4f

  type AdminOrigin = frame_system::EnsureRoot<AccountId>;

We could not run this extrinsic in production, because there is a line trying to unwrap the origin:

• PINT/pallets/asset-index/src/lib.rs

  Line 173 in 4fcfc4f

  T::AdminOrigin::ensure_origin(origin.clone())?;

and unwrapping RawOrigin::Root will cause BadOrigin, we can modify the EnsureRoot to EnsureSigned for tests or set up an admin account now

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We could probably use this initial rate until a price feed exists for this asset?

I agree with this idea, I can implement this in #91 or we create another PR?

And this implementation will solve the problem I meet in #93 rn , configuring an initial rate in runtime, then I don't need to create a feed in the benchmarks of one specific pallet.

[mattsse]

This should be its own PR, because it requires some changes within either the price pair or asset index pallet I think,
I guess best way to go would be to add this initial rate as fallback when no price feed could be feed.
So this would mean on add_asset the PINT/asset pair is determined based on the given extrinsic arguments and inserted/updated as PricePair somewhere.