docs: add TestSetRealm reference docs (#2369)

<!-- please provide a detailed description of the changes made in this
pull request. -->

## Description

This PR adds `TestSetRealm` docs, as well as related docs. It also fixes
up a few minor details.

Closes: #2273 

<details><summary>Contributors' checklist...</summary>

- [x] Added new tests, or not needed, or not feasible
- [x] Provided an example (e.g. screenshot) to aid review or the PR is
self-explanatory
- [x] Updated the official documentation or not needed
- [x] No breaking changes were made, or a `BREAKING CHANGE: xxx` message
was included in the description
- [x] Added references to related issues and PRs
- [ ] Provided any useful hints for running manual tests
- [ ] Added new benchmarks to [generated
graphs](https://gnoland.github.io/benchmarks), if any. More info
[here](https://github.com/gnolang/gno/blob/master/.benchmarks/README.md).
</details>

---------

Co-authored-by: Morgan <[email protected]>

docs/reference/stdlibs/std/testing.md

@@ -10,11 +10,15 @@ func TestSetOrigCaller(addr Address)
 func TestSetOrigPkgAddr(addr Address)
 func TestSetOrigSend(sent, spent Coins)
 func TestIssueCoins(addr Address, coins Coins)
+func TestSetRealm(realm Realm)
+func NewUserRealm(address Address)
+func NewCodeRealm(pkgPath string)
 ```
 
 ---
 
 ## TestSkipHeights
+
 ```go
 func TestSkipHeights(count int64)
 ```
@@ -29,30 +33,34 @@ std.TestSkipHeights(100)
 ---
 
 ## TestSetOrigCaller
+
 ```go
 func TestSetOrigCaller(addr Address)
 ```
 Sets the current caller of the transaction to **addr**.
 
 #### Usage
 ```go
-std.TestSetOrigCaller("g1jg8mtutu9khhfwc4nxmuhcpftf0pajdhfvsqf5")
+std.TestSetOrigCaller(std.Address("g1jg8mtutu9khhfwc4nxmuhcpftf0pajdhfvsqf5"))
 ```
 ---
 
 ## TestSetOrigPkgAddr
+
 ```go
 func TestSetOrigPkgAddr(addr Address)
 ```
-Sets the current realm/package address to **addr**.
+Sets the call entry realm address to **addr**.
 
 #### Usage
 ```go
-std.TestSetOrigPkgAddr("g1ecely4gjy0yl6s9kt409ll330q9hk2lj9ls3ec")
+std.TestSetOrigPkgAddr(std.Address("g1ecely4gjy0yl6s9kt409ll330q9hk2lj9ls3ec"))
 ```
+
 ---
 
 ## TestSetOrigSend
+
 ```go
 func TestSetOrigSend(sent, spent Coins)
 ```
@@ -65,17 +73,78 @@ std.TestSetOrigSend(sent, spent Coins)
 ---
 
 ## TestIssueCoins
+
 ```go
 func TestIssueCoins(addr Address, coins Coins)
 ```
+
 Issues testing context **coins** to **addr**.
+
 #### Usage
+
 ```go
 issue := std.Coins{{"coin1", 100}, {"coin2", 200}}
-addr := "g1ecely4gjy0yl6s9kt409ll330q9hk2lj9ls3ec"
+addr := std.Address("g1ecely4gjy0yl6s9kt409ll330q9hk2lj9ls3ec")
 std.TestIssueCoins(addr, issue)
 ```
 
+---
+
+## TestSetRealm
+
+```go
+func TestSetRealm(rlm Realm)
+```
+
+Sets the realm for the current frame. After calling `TestSetRealm()`, calling 
+[`CurrentRealm()`](chain.md#currentrealm) in the same test function will yield the value of `rlm`, and 
+any `PrevRealm()` called from a function used after TestSetRealm will yield `rlm`.
+
+Should be used in combination with [`NewUserRealm`](#newuserrealm) &
+[`NewCodeRealm`](#newcoderealm).
+
+#### Usage
+```go
+addr := std.Address("g1ecely4gjy0yl6s9kt409ll330q9hk2lj9ls3ec")
+std.TestSetRealm(std.NewUserRealm(""))
+// or 
+std.TestSetRealm(std.NewCodeRealm("gno.land/r/demo/users"))
+```
+
+---
+
+## NewUserRealm
+
+```go
+func NewUserRealm(address Address) Realm
+```
+
+Creates a new user realm for testing purposes.
+
+#### Usage
+```go
+addr := std.Address("g1ecely4gjy0yl6s9kt409ll330q9hk2lj9ls3ec")
+userRealm := std.NewUserRealm(addr)
+```
+
+---
+
+## NewCodeRealm
+
+```go
+func NewCodeRealm(pkgPath string)
+```
+
+Creates a new code realm for testing purposes.
+
+#### Usage
+```go
+path := "gno.land/r/demo/boards"
+codeRealm := std.NewCodeRealm(path)
+```
+
+
+
 
 
 

gnovm/tests/stdlibs/std/std.gno

@@ -9,7 +9,7 @@ func TestSetOrigCaller(addr Address)  { testSetOrigCaller(string(addr)) }
 func TestSetOrigPkgAddr(addr Address) { testSetOrigPkgAddr(string(addr)) }
 
 // TestSetRealm sets the realm for the current frame.
-// After calling TestSetRealm, calling CurrentRealm() will yield the value of
+// After calling TestSetRealm, calling CurrentRealm() in the test function will yield the value of
 // rlm, while if a realm function is called, using PrevRealm() will yield rlm.
 func TestSetRealm(rlm Realm) {
 	testSetRealm(string(rlm.addr), rlm.pkgPath)