feat(stdlibs/std)!: change TestSetPrevRealm to TestSetRealm (#2164)

This PR removes the `TestSetPrevRealm` and `TestSetPrevAddr`, added in
#890, in favour of a new API `TestSetRealm`, which is more flexible in
its behaviour.

The function works by setting the result of `CurrentRealm()` for the
frame in which the `TestSetRealm` function is called. Consequently,
calling `PrevRealm` in any function called within will yield the value
passed to `TestSetRealm`.

`TestSetRealm` allows to transparently set "user" and "code" realms, by
using two new costructors in the testing stdlibs, `std.NewUserRealm` and
`std.NewCodeRealm`, allowing emulation of both kinds of callers.

The call is not `TestSetPrevRealm` as it does not permanently "set" the
value returned by PrevRealm, as if in a mock; it simply changes the
Realm of the current frame, allowing "deep" calls to PrevRealm() to
correctly return the value of the previous realm.


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

- [ ] Added new tests, or not needed, or not feasible
- [ ] Provided an example (e.g. screenshot) to aid review or the PR is
self-explanatory
- [ ] Updated the official documentation or not needed
- [ ] No breaking changes were made, or a `BREAKING CHANGE: xxx` message
was included in the description
- [ ] 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>

gnovm/pkg/gnolang/machine.go

@@ -2058,19 +2058,19 @@ func (m *Machine) String() string {
 		builder.WriteString(fmt.Sprintf("          #%d %v\n", i, m.Values[i]))
 	}
 
-	builder.WriteString(`Exprs: `)
+	builder.WriteString("    Exprs:\n")
 
 	for i := len(m.Exprs) - 1; i >= 0; i-- {
 		builder.WriteString(fmt.Sprintf("          #%d %v\n", i, m.Exprs[i]))
 	}
 
-	builder.WriteString(`Stmts: `)
+	builder.WriteString("    Stmts:\n")
 
 	for i := len(m.Stmts) - 1; i >= 0; i-- {
 		builder.WriteString(fmt.Sprintf("          #%d %v\n", i, m.Stmts[i]))
 	}
 
-	builder.WriteString(`Blocks: `)
+	builder.WriteString("    Blocks:\n")
 
 	for b := m.LastBlock(); b != nil; {
 		gen := builder.Len()/3 + 1
@@ -2107,7 +2107,7 @@ func (m *Machine) String() string {
 		}
 	}
 
-	builder.WriteString(`Blocks (other): `)
+	builder.WriteString("    Blocks (other):\n")
 
 	for i := len(m.Blocks) - 2; i >= 0; i-- {
 		b := m.Blocks[i]
@@ -2119,17 +2119,17 @@ func (m *Machine) String() string {
 		if _, ok := b.Source.(*PackageNode); ok {
 			break // done, skip *PackageNode.
 		} else {
-			builder.WriteString(fmt.Sprintf("          #%d %s", i,
+			builder.WriteString(fmt.Sprintf("          #%d %s\n", i,
 				b.StringIndented("            ")))
 			if b.Source != nil {
 				sb := b.GetSource(m.Store).GetStaticBlock().GetBlock()
-				builder.WriteString(fmt.Sprintf(" (static) #%d %s", i,
+				builder.WriteString(fmt.Sprintf(" (static) #%d %s\n", i,
 					sb.StringIndented("            ")))
 			}
 		}
 	}
 
-	builder.WriteString(`Frames: `)
+	builder.WriteString("    Frames:\n")
 
 	for i := len(m.Frames) - 1; i >= 0; i-- {
 		builder.WriteString(fmt.Sprintf("          #%d %s\n", i, m.Frames[i]))
@@ -2139,7 +2139,7 @@ func (m *Machine) String() string {
 		builder.WriteString(fmt.Sprintf("    Realm:\n      %s\n", m.Realm.Path))
 	}
 
-	builder.WriteString(`Exceptions: `)
+	builder.WriteString("    Exceptions:\n")
 
 	for _, ex := range m.Exceptions {
 		builder.WriteString(fmt.Sprintf("      %s\n", ex.Sprint(m)))

gnovm/stdlibs/std/banker.go

@@ -37,14 +37,14 @@ const (
 var reDenom = regexp.MustCompile("[a-z][a-z0-9]{2,15}")
 
 func X_bankerGetCoins(m *gno.Machine, bt uint8, addr string) (denoms []string, amounts []int64) {
-	coins := m.Context.(ExecContext).Banker.GetCoins(crypto.Bech32Address(addr))
+	coins := GetContext(m).Banker.GetCoins(crypto.Bech32Address(addr))
 	return ExpandCoins(coins)
 }
 
 func X_bankerSendCoins(m *gno.Machine, bt uint8, fromS, toS string, denoms []string, amounts []int64) {
 	// bt != BankerTypeReadonly (checked in gno)
 
-	ctx := m.Context.(ExecContext)
+	ctx := GetContext(m)
 	amt := CompactCoins(denoms, amounts)
 	from, to := crypto.Bech32Address(fromS), crypto.Bech32Address(toS)
 
@@ -87,7 +87,7 @@ func X_bankerSendCoins(m *gno.Machine, bt uint8, fromS, toS string, denoms []str
 }
 
 func X_bankerTotalCoin(m *gno.Machine, bt uint8, denom string) int64 {
-	return m.Context.(ExecContext).Banker.TotalCoin(denom)
+	return GetContext(m).Banker.TotalCoin(denom)
 }
 
 func X_bankerIssueCoin(m *gno.Machine, bt uint8, addr string, denom string, amount int64) {
@@ -104,7 +104,7 @@ func X_bankerIssueCoin(m *gno.Machine, bt uint8, addr string, denom string, amou
 	// ibc_denom := 'ibc/' + hash('path' + 'base_denom')
 	// gno_realm_denom := '/' + 'pkg_path' + ':' + 'base_denom'
 	newDenom := "/" + m.Realm.Path + ":" + denom
-	m.Context.(ExecContext).Banker.IssueCoin(crypto.Bech32Address(addr), newDenom, amount)
+	GetContext(m).Banker.IssueCoin(crypto.Bech32Address(addr), newDenom, amount)
 }
 
 func X_bankerRemoveCoin(m *gno.Machine, bt uint8, addr string, denom string, amount int64) {
@@ -117,5 +117,5 @@ func X_bankerRemoveCoin(m *gno.Machine, bt uint8, addr string, denom string, amo
 	}
 
 	newDenom := "/" + m.Realm.Path + ":" + denom
-	m.Context.(ExecContext).Banker.RemoveCoin(crypto.Bech32Address(addr), newDenom, amount)
+	GetContext(m).Banker.RemoveCoin(crypto.Bech32Address(addr), newDenom, amount)
 }

gnovm/stdlibs/std/context.go

@@ -1,6 +1,7 @@
 package std
 
 import (
+	gno "github.com/gnolang/gno/gnovm/pkg/gnolang"
 	"github.com/gnolang/gno/tm2/pkg/crypto"
 	"github.com/gnolang/gno/tm2/pkg/sdk"
 	"github.com/gnolang/gno/tm2/pkg/std"
@@ -19,3 +20,28 @@ type ExecContext struct {
 	Banker        BankerInterface
 	EventLogger   *sdk.EventLogger
 }
+
+// GetContext returns the execution context.
+// This is used to allow extending the exec context using interfaces,
+// for instance when testing.
+func (e ExecContext) GetExecContext() ExecContext {
+	return e
+}
+
+var _ ExecContexter = ExecContext{}
+
+// ExecContexter is a type capable of returning the parent [ExecContext]. When
+// using these standard libraries, m.Context should always implement this
+// interface. This can be obtained by embedding [ExecContext].
+type ExecContexter interface {
+	GetExecContext() ExecContext
+}
+
+// NOTE: In order to make this work by simply embedding ExecContext in another
+// context (like TestExecContext), the method needs to be something other than
+// the field name.
+
+// GetContext returns the context from the Gno machine.
+func GetContext(m *gno.Machine) ExecContext {
+	return m.Context.(ExecContexter).GetExecContext()
+}

gnovm/stdlibs/std/emit_event.go

@@ -26,7 +26,7 @@ func X_emit(m *gno.Machine, typ string, attrs []string) {
 		Func:       fnIdent,
 		Attributes: eventAttrs,
 	}
-	ctx := m.Context.(ExecContext)
+	ctx := GetContext(m)
 	ctx.EventLogger.EmitEvent(evt)
 }
 

gnovm/stdlibs/std/native.go

@@ -24,11 +24,11 @@ func IsOriginCall(m *gno.Machine) bool {
 }
 
 func GetChainID(m *gno.Machine) string {
-	return m.Context.(ExecContext).ChainID
+	return GetContext(m).ChainID
 }
 
 func GetHeight(m *gno.Machine) int64 {
-	return m.Context.(ExecContext).Height
+	return GetContext(m).Height
 }
 
 // getPrevFunctionNameFromTarget returns the last called function name (identifier) from the call stack.
@@ -63,16 +63,16 @@ func findPrevFuncName(m *gno.Machine, targetIndex int) string {
 }
 
 func X_origSend(m *gno.Machine) (denoms []string, amounts []int64) {
-	os := m.Context.(ExecContext).OrigSend
+	os := GetContext(m).OrigSend
 	return ExpandCoins(os)
 }
 
 func X_origCaller(m *gno.Machine) string {
-	return string(m.Context.(ExecContext).OrigCaller)
+	return string(GetContext(m).OrigCaller)
 }
 
 func X_origPkgAddr(m *gno.Machine) string {
-	return string(m.Context.(ExecContext).OrigPkgAddr)
+	return string(GetContext(m).OrigPkgAddr)
 }
 
 func X_callerAt(m *gno.Machine, n int) string {
@@ -91,22 +91,24 @@ func X_callerAt(m *gno.Machine, n int) string {
 	}
 	if n == m.NumFrames() {
 		// This makes it consistent with GetOrigCaller.
-		ctx := m.Context.(ExecContext)
+		ctx := GetContext(m)
 		return string(ctx.OrigCaller)
 	}
 	return string(m.MustLastCallFrame(n).LastPackage.GetPkgAddr().Bech32())
 }
 
 func X_getRealm(m *gno.Machine, height int) (address, pkgPath string) {
+	// NOTE: keep in sync with test/stdlibs/std.getRealm
+
 	var (
-		ctx           = m.Context.(ExecContext)
+		ctx           = GetContext(m)
 		currentCaller crypto.Bech32Address
 		// Keeps track of the number of times currentCaller
 		// has changed.
 		changes int
 	)
 
-	for i := m.NumFrames() - 1; i > 0; i-- {
+	for i := m.NumFrames() - 1; i >= 0; i-- {
 		fr := m.Frames[i]
 		if fr.LastPackage == nil || !fr.LastPackage.IsRealm() {
 			continue

gnovm/stdlibs/stdlibs.go

@@ -9,6 +9,10 @@ import (
 
 type ExecContext = libsstd.ExecContext
 
+func GetContext(m *gno.Machine) ExecContext {
+	return libsstd.GetContext(m)
+}
+
 func NativeStore(pkgPath string, name gno.Name) func(*gno.Machine) {
 	for _, nf := range nativeFuncs {
 		if nf.gnoPkg == pkgPath && name == nf.gnoFunc {

gnovm/stdlibs/time/time.go

@@ -12,6 +12,6 @@ func X_now(m *gno.Machine) (sec int64, nsec int32, mono int64) {
 		return 0, 0, 0
 	}
 
-	ctx := m.Context.(std.ExecContext)
+	ctx := std.GetContext(m)
 	return ctx.Timestamp, int32(ctx.TimestampNano), ctx.Timestamp*int64(time.Second) + ctx.TimestampNano
 }

gnovm/tests/file.go

@@ -15,6 +15,7 @@ import (
 
 	gno "github.com/gnolang/gno/gnovm/pkg/gnolang"
 	"github.com/gnolang/gno/gnovm/stdlibs"
+	teststd "github.com/gnolang/gno/gnovm/tests/stdlibs/std"
 	"github.com/gnolang/gno/tm2/pkg/crypto"
 	osm "github.com/gnolang/gno/tm2/pkg/os"
 	"github.com/gnolang/gno/tm2/pkg/sdk"
@@ -46,7 +47,7 @@ func testMachineCustom(store gno.Store, pkgPath string, stdout io.Writer, maxAll
 	return m
 }
 
-func testContext(pkgPath string, send std.Coins) stdlibs.ExecContext {
+func testContext(pkgPath string, send std.Coins) *teststd.TestExecContext {
 	// FIXME: create a better package to manage this, with custom constructors
 	pkgAddr := gno.DerivePkgAddr(pkgPath) // the addr of the pkgPath called.
 	caller := gno.DerivePkgAddr("user1.gno")
@@ -65,7 +66,10 @@ func testContext(pkgPath string, send std.Coins) stdlibs.ExecContext {
 		Banker:        banker,
 		EventLogger:   sdk.NewEventLogger(),
 	}
-	return ctx
+	return &teststd.TestExecContext{
+		ExecContext: ctx,
+		RealmFrames: make(map[*gno.Frame]teststd.RealmOverride),
+	}
 }
 
 type runFileTestOptions struct {

gnovm/tests/files/zrealm_crossrealm13.gno

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"std"
+)
+
+func main() {
+	PrintRealm()
+	println(pad("CurrentRealm:"), std.CurrentRealm())
+	println(pad("PrevRealm:"), std.PrevRealm())
+	std.TestSetRealm(std.NewUserRealm("g1user"))
+	PrintRealm()
+	println(pad("CurrentRealm:"), std.CurrentRealm())
+	println(pad("PrevRealm:"), std.PrevRealm())
+	std.TestSetRealm(std.NewCodeRealm("gno.land/r/demo/users"))
+	PrintRealm()
+	println(pad("CurrentRealm:"), std.CurrentRealm())
+	println(pad("PrevRealm:"), std.PrevRealm())
+}
+
+func pad(s string) string {
+	for len(s) < 26 {
+		s += " "
+	}
+	return s
+}
+
+func PrintRealm() {
+	println(pad("PrintRealm: CurrentRealm:"), std.CurrentRealm())
+	println(pad("PrintRealm: PrevRealm:"), std.PrevRealm())
+}
+
+// Because this is the context of a package, using PrintRealm()
+// should not change the output of the main function.
+
+// Output:
+// PrintRealm: CurrentRealm:  (struct{("g1wymu47drhr0kuq2098m792lytgtj2nyx77yrsm" std.Address),("" string)} std.Realm)
+// PrintRealm: PrevRealm:     (struct{("g1wymu47drhr0kuq2098m792lytgtj2nyx77yrsm" std.Address),("" string)} std.Realm)
+// CurrentRealm:              (struct{("g1wymu47drhr0kuq2098m792lytgtj2nyx77yrsm" std.Address),("" string)} std.Realm)
+// PrevRealm:                 (struct{("g1wymu47drhr0kuq2098m792lytgtj2nyx77yrsm" std.Address),("" string)} std.Realm)
+// PrintRealm: CurrentRealm:  (struct{("g1user" std.Address),("" string)} std.Realm)
+// PrintRealm: PrevRealm:     (struct{("g1wymu47drhr0kuq2098m792lytgtj2nyx77yrsm" std.Address),("" string)} std.Realm)
+// CurrentRealm:              (struct{("g1user" std.Address),("" string)} std.Realm)
+// PrevRealm:                 (struct{("g1wymu47drhr0kuq2098m792lytgtj2nyx77yrsm" std.Address),("" string)} std.Realm)
+// PrintRealm: CurrentRealm:  (struct{("g17m4ga9t9dxn8uf06p3cahdavzfexe33ecg8v2s" std.Address),("gno.land/r/demo/users" string)} std.Realm)
+// PrintRealm: PrevRealm:     (struct{("g1wymu47drhr0kuq2098m792lytgtj2nyx77yrsm" std.Address),("" string)} std.Realm)
+// CurrentRealm:              (struct{("g17m4ga9t9dxn8uf06p3cahdavzfexe33ecg8v2s" std.Address),("gno.land/r/demo/users" string)} std.Realm)
+// PrevRealm:                 (struct{("g1wymu47drhr0kuq2098m792lytgtj2nyx77yrsm" std.Address),("" string)} std.Realm)