Fixing "Failed to get Recent Blockhash" Error in Solana Development with Anchor Framework

I took a break from exploring development in Solana, and the first thing I hit when I recently resumed again was failing tests when using the Anchor framework.

Running anchor run test leads to this error:

  1) calculator
  Is initialized!:
  Error: failed to get recent blockhash: FetchError:
  request to http://localhost:8899/ failed, reason:
  connect ECONNREFUSED ::1:8899
  at Connection.getLatestBlockhash
  (node_modules/@solana/web3.js/src/connection.ts:4555:13)
  at processTicksAndRejections
  (node:internal/process/task_queues:95:5)
  at AnchorProvider.sendAndConfirm
  (node_modules/@coral-xyz/anchor/src/provider.ts:147:9)
  at MethodsBuilder.rpc [as _rpcFn]
  (node_modules/@coral-xyz/anchor/src/program/namespace/rpc.ts:29:16)

The important part of the error message is:

Error: failed to get recent blockhash: FetchError:
request to http://localhost:8899/ failed, reason:
connect ECONNREFUSED ::1:8899
      at Connection.getLatestBlockhash

Googling the error, I found this suggestion here which says to "Try using node 16 instead of 17 if you're on 17".

I tried this and sure this works. But it does not feel right. node's current version is 20.x, dropping down to version 16 does not feel like the most appropriate way to solve this problem.

So why is the issue happening in the first place? Maybe if we understand that, we can come up with a better solution.

A Short Note on Types in Rust

Types, loosely defined, are about capabilities. What are the capabilities available on a value of a certain type? Programmers experienced with strong and statically typed languages will probably have a more visceral appreciation of this, but even programmers of weakly and dynamically typed languages like JavaScript, encounter the reality of types and their capabilities; only that they do so at runtime.

For example, a JavaScript developer might type out the following code:

> "3".toExponential()

But this will fail at runtime because the "3" is of the String type and it does not have the capability to be shown as exponential. The following, on the other hand, will work seamlessly:

> (3).toExponential()
'3e+0'

Because 3 is of the number type and the number type has the capability to be formatted in exponential form.

Rust extends the idea of types to now include capabilities that relate to memory management. These capabilities ensure memory safety in Rust.