feat: add simple address validity check (gnolang#1303)

## Description

This PR adds a simple `Valid()` check to the Address type. It is there
to prevent most human errors, and doesn't actually validate the math
behind bech32 (for now) - it relies only on the length of the address.

Running `gno test .` will run the unit test for the `Valid()` function.
Closes: gnolang#1298 

<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>

---------

Signed-off-by: moul <94029+moul@users.noreply.github.com>
Co-authored-by: moul <94029+moul@users.noreply.github.com>

examples/gno.land/p/demo/grc/grc1155/util.gno

@@ -7,7 +7,7 @@ import (
 const zeroAddress std.Address = ""
 
 func isValidAddress(addr std.Address) bool {
-	if addr.String() == "" {
+	if !addr.IsValid() {
 		return false
 	}
 	return true

examples/gno.land/p/demo/grc/grc20/util.gno

@@ -5,7 +5,7 @@ import "std"
 const zeroAddress = std.Address("")
 
 func checkIsValidAddress(addr std.Address) error {
-	if addr.String() == "" {
+	if !addr.IsValid() {
 		return ErrInvalidAddress
 	}
 	return nil

examples/gno.land/p/demo/grc/grc721/util.gno

@@ -7,7 +7,7 @@ import (
 var zeroAddress = std.Address("")
 
 func isValidAddress(addr std.Address) error {
-	if addr.String() == "" {
+	if !addr.IsValid() {
 		return ErrInvalidAddress
 	}
 	return nil

gnovm/stdlibs/std/crypto.gno

@@ -6,6 +6,11 @@ func (a Address) String() string {
 	return string(a)
 }
 
+// IsValid checks if the address is of specific length. Doesn't check prefix or checksum for the address
+func (a Address) IsValid() bool {
+	return len(a) == RawAddressSize*2 // hex length
+}
+
 const RawAddressSize = 20
 
 type RawAddress [RawAddressSize]byte

gnovm/stdlibs/std/crypto_test.gno

@@ -0,0 +1,30 @@
+package std
+
+import (
+	"testing"
+)
+
+func TestValid(t *testing.T) {
+	type test struct {
+		inputAddress Address
+		expected     bool
+	}
+
+	testCases := []test{
+		{inputAddress: "g1f4v282mwyhu29afke4vq5r2xzcm6z3ftnugcnv", expected: true},
+		{inputAddress: "g127jydsh6cms3lrtdenydxsckh23a8d6emqcvfa", expected: true},
+		{inputAddress: "g1u7y667z64x2h7vc6fmpcprgey4ck233jaww9zq", expected: true},
+		{inputAddress: "g14da4n9hcynyzz83q607uu8keuh9hwlv42ra6fa", expected: true},
+		{inputAddress: "", expected: false},
+		{inputAddress: "000000000000", expected: false},
+		{inputAddress: "0000000000000000000000000000000000000000000000000000000000000000000000", expected: false},
+	}
+
+	for _, tc := range testCases {
+		result := tc.inputAddress.IsValid()
+
+		if result != tc.expected {
+			t.Fatalf("Expected: %t, got: %t", tc.expected, result)
+		}
+	}
+}

gnovm/stdlibs/stdshim/crypto.gno

@@ -6,6 +6,11 @@ func (a Address) String() string {
 	return string(a)
 }
 
+// IsValid checks if the address is of specific length. Doesn't check prefix or checksum for the address
+func (a Address) IsValid() bool {
+	return len(a) == RawAddressSize*2 // hex length
+}
+
 const RawAddressSize = 20
 
 type RawAddress [RawAddressSize]byte

go.mod

@@ -61,7 +61,7 @@ require (
 	github.com/kr/text v0.2.0 // indirect
 	github.com/lib/pq v1.10.7 // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
-	github.com/nxadm/tail v1.4.8 // indirect
+	github.com/nxadm/tail v1.4.11 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/rivo/uniseg v0.4.3 // indirect
 	go.opencensus.io v0.22.5 // indirect