x/evidence doc general audit & cleanup (#8277)

* Update x/evidence doc

* Update x/evidence spec

x/evidence/doc.go

@@ -20,13 +20,11 @@ A full setup of the evidence module may look something as follows:
 	  evidence.AppModuleBasic{},
 	)
 
-	// First, create the keeper's subspace for parameters and the keeper itself.
+	// First, create the keeper
-	evidenceParamspace := app.ParamsKeeper.Subspace(evidence.ModuleName)
 	evidenceKeeper := evidence.NewKeeper(
-	  app.cdc, keys[evidence.StoreKey], evidenceParamspace, evidence.DefaultCodespace,
+	  appCodec, keys[evidence.StoreKey], &app.StakingKeeper, app.SlashingKeeper,
 	)
 
-
 	// Second, create the evidence Handler and register all desired routes.
 	evidenceRouter := evidence.NewRouter().
 	  AddRoute(evidenceRoute, evidenceHandler).
@@ -34,9 +32,11 @@ A full setup of the evidence module may look something as follows:
 
 	evidenceKeeper.SetRouter(evidenceRouter)
 
+	app.EvidenceKeeper = *evidenceKeeper
+
 	app.mm = module.NewManager(
 	  // ...
-	  evidence.NewAppModule(evidenceKeeper),
+	  evidence.NewAppModule(app.EvidenceKeeper),
 	)
 
 	// Remaining application bootstrapping...

x/evidence/spec/01_concepts.md

@@ -16,6 +16,8 @@ has also been created to define a contract for evidence against malicious valida
 // Evidence defines the contract which concrete evidence types of misbehavior
 // must implement.
 type Evidence interface {
+	proto.Message
+
 	Route() string
 	Type() string
 	String() string
@@ -71,5 +73,5 @@ capabilities such as slashing and jailing a validator.
 // for executing all corresponding business logic necessary for verifying the
 // evidence as valid. In addition, the Handler may execute any necessary
 // slashing and potential jailing.
-type Handler func(Context, Evidence) error
+type Handler func(sdk.Context, Evidence) error
 ```

x/evidence/spec/03_messages.md

@@ -27,17 +27,24 @@ as follows:
 ```go
 func SubmitEvidence(ctx Context, evidence Evidence) error {
   if _, ok := GetEvidence(ctx, evidence.Hash()); ok {
-    return ErrEvidenceExists(codespace, evidence.Hash().String())
+    return sdkerrors.Wrap(types.ErrEvidenceExists, evidence.Hash().String())
   }
   if !router.HasRoute(evidence.Route()) {
-    return ErrNoEvidenceHandlerExists(codespace, evidence.Route())
+    return sdkerrors.Wrap(types.ErrNoEvidenceHandlerExists, evidence.Route())
   }
 
   handler := router.GetRoute(evidence.Route())
   if err := handler(ctx, evidence); err != nil {
-    return ErrInvalidEvidence(codespace, err.Error())
+    return sdkerrors.Wrap(types.ErrInvalidEvidence, err.Error())
   }
 
+  ctx.EventManager().EmitEvent(
+		sdk.NewEvent(
+			types.EventTypeSubmitEvidence,
+			sdk.NewAttribute(types.AttributeKeyEvidenceHash, evidence.Hash().String()),
+		),
+	)
+
   SetEvidence(ctx, evidence)
   return nil
 }
@@ -45,4 +52,4 @@ func SubmitEvidence(ctx Context, evidence Evidence) error {
 
 First, there must not already exist valid submitted `Evidence` of the exact same
 type. Secondly, the `Evidence` is routed to the `Handler` and executed. Finally,
-if there is no error in handling the `Evidence`, it is persisted to state.
+if there is no error in handling the `Evidence`, an event is emitted and it is persisted to state.