refactor(agent,scrt,cw): common implementation of Chain#ready

- deduplicate
- maybe in this case it's possible to give Chain a .then() method
that resolves to this + this.api, effectively giving an async constructor?

agent/agent-chain.ts

@@ -190,6 +190,30 @@ export abstract class Chain {
   /** Return self. */
   get chain () { return this }
 
+  api?: unknown
+
+  abstract getApi (): unknown
+
+  get ready () {
+    if (this.isDevnet && !this.devnet) {
+      throw new Error("the chain is marked as a devnet but is missing the devnet handle")
+    }
+    type This = this
+    type ThisWithApi = This & { api: NonNullable<This["api"]> }
+    const init = new Promise<ThisWithApi>(async (resolve, reject)=>{
+      if (this.isDevnet) {
+        await this.devnet!.start()
+      }
+      if (!this.api) {
+        if (!this.url) throw new Error("the chain's url property is not set")
+        this.api = await Promise.resolve(this.getApi())
+      }
+      return resolve(this as ThisWithApi)
+    })
+    Object.defineProperty(this, 'ready', { get () { return init } })
+    return init
+  }
+
   /** Wait for the block height to increment. */
   get nextBlock (): Promise<number> {
     return this.height.then(async startingHeight=>{
@@ -296,6 +320,11 @@ export class StubChain extends Chain {
 
   defaultDenom = 'stub'
 
+  getApi (): {} {
+    this.log.warn('chain.getApi: this function is stub; use a subclass of Chain')
+    return Promise.resolve({})
+  }
+
   /** Get the current block height. */
   get height (): Promise<number> {
     this.log.warn('chain.height: this getter is stub; use a subclass of Chain')

connect/cw/cw-base.ts

@@ -34,27 +34,10 @@ class CWChain extends Chain {
   defaultDenom = ''
 
   /** Query-only API handle. */
-  api?: CosmWasmClient
+  declare api?: CosmWasmClient
 
-  /** One-shot async initialization of chain.
-    * Populates the `api` property with a CosmWasmClient. */
-  get ready (): Promise<this & { api: CosmWasmClient }> {
-    if (this.isDevnet && !this.devnet) {
-      throw new Error("the chain is marked as a devnet but is missing the devnet handle")
-    }
-    const init = new Promise<this & { api: CosmWasmClient }>(async (resolve, reject)=>{
-      if (this.isDevnet) {
-        await this.devnet!.start()
-      }
-      if (!this.api) {
-        if (!this.url) throw new CWError("the chain's url property is not set")
-        const api = await CosmWasmClient.connect(this.url)
-        this.api = api
-      }
-      return resolve(this as this & { api: CosmWasmClient })
-    })
-    Object.defineProperty(this, 'ready', { get () { return init } })
-    return init
+  async getApi (): Promise<CosmWasmClient> {
+    return await CosmWasmClient.connect(this.url)
   }
 
   get block (): Promise<Block> {

connect/scrt/scrt-chain.ts

@@ -35,33 +35,7 @@ class ScrtChain extends Chain {
   Agent: AgentClass<ScrtAgent> = ScrtChain.Agent
 
   /** A fresh instance of the anonymous read-only API client. Memoize yourself. */
-  api?: SecretNetworkClient
-
-  constructor (options: Partial<ScrtChain> = {
-    url:  ScrtChain.Config.defaultMainnetUrl,
-    mode: Chain.Mode.Mainnet
-  }) {
-    super(options)
-    this.log.label = `${this.id}`
-  }
-
-  get ready (): Promise<this & { api: SecretNetworkClient }> {
-    if (this.isDevnet && !this.devnet) {
-      throw new Error("the chain is marked as a devnet but is missing the devnet handle")
-    }
-    const init = new Promise<this & { api: SecretNetworkClient }>(async (resolve, reject)=>{
-      if (this.isDevnet) {
-        await this.devnet!.start()
-      }
-      if (!this.api) {
-        if (!this.url) throw new Error("the chain's url property is not set")
-        this.api = this.getApi()
-      }
-      return resolve(this as this & { api: SecretNetworkClient })
-    })
-    Object.defineProperty(this, 'ready', { get () { return init } })
-    return init
-  }
+  declare api?: SecretNetworkClient
 
   /** @returns a fresh instance of the anonymous read-only API client. */
   getApi (options: Partial<CreateClientOptions> = {}): SecretNetworkClient {
@@ -185,13 +159,18 @@ export type { TxResponse }
 /** Represents a connection to the Secret Network,
   * authenticated as a specific address. */
 class ScrtAgent extends Agent {
+
   log = new Console('ScrtAgent')
+
   /** Downcast chain property to Scrt only. */
   declare chain: ScrtChain
+
   /** Batch class used by this agent. */
   Batch: BatchClass<ScrtBatch> = ScrtAgent.Batch
+
   /** Whether to simulate each execution first to get a more accurate gas estimate. */
   simulateForGas: boolean = false
+
   /** Default fees for this agent. */
   fees = ScrtChain.defaultFees
 
@@ -208,10 +187,10 @@ class ScrtAgent extends Agent {
   }
 
   get ready (): Promise<this & { api: SecretNetworkClient }> {
-    // Require chain reference to be populated.
-    if (!this.chain) throw new Error.Missing.Chain()
     // If an API instance is already available (e.g. provided to constructor), just use that.
     if (this.api) return Promise.resolve(this as this & { api: SecretNetworkClient })
+    // Require chain reference to be populated.
+    if (!this.chain) throw new Error.Missing.Chain()
     // Begin asynchronous init.
     const init = new Promise<this & { api: SecretNetworkClient }>(async (
       resolve, reject

connect/scrt/scrt-mocknet.ts

@@ -234,6 +234,10 @@ export class Mocknet extends Chain {
       )
     }
   }
+
+  getApi () {
+    return Promise.resolve({})
+  }
 }
 
 class MocknetAgent extends Agent {