test(gnovm): "*_filetest.gno" instructions

Add tests for Output, Error and Realm instructions

The change introduces a new test dependency
github.com/rogpeppe/go-internal/testscripts, which allows to create
tests bases on txtar files. This is very handy for this kind of tests,
because:
- you can easily creates a set of files that can be used for a command
  (here the `gno test` command)
- you can assert stderr and stdout expectations in a very readable and
  maintainable way
- you can compare files using the `cmp` command, which is very useful to
  assert of the `-update-golden-tests` behavior.

These tests were added to help work on gnolang#1015, which will potentially
alter the behavior of "*filetest.gno" instructions updates.

gnovm/tests/file_test.go

@@ -2,13 +2,18 @@ package tests
 
 import (
 	"flag"
+	"fmt"
 	"io/fs"
 	"os"
+	"os/exec"
 	"path"
 	"path/filepath"
 	"strings"
 	"testing"
 
+	"github.com/rogpeppe/go-internal/testscript"
+	"github.com/stretchr/testify/require"
+
 	gno "github.com/gnolang/gno/gnovm/pkg/gnolang"
 )
 
@@ -100,3 +105,30 @@ func runFileTest(t *testing.T, path string, opts ...RunFileTestOption) {
 		t.Fatalf("got error: %v", err)
 	}
 }
+
+func TestRunFileTest(t *testing.T) {
+	// Get root location of github.com/gnolang/gno
+	goModPath, err := exec.Command("go", "env", "GOMOD").CombinedOutput()
+	require.NoError(t, err)
+	rootDir := path.Dir(string(goModPath))
+	// Build a fresh gno binary in a temp directory
+	gnoBin := path.Join(t.TempDir(), "gno")
+	err = exec.Command("go", "build", "-o", gnoBin, path.Join(rootDir, "gnovm", "cmd", "gno")).Run()
+	fmt.Println(exec.Command("go", "build", path.Join(rootDir, "gnovm", "cmd", "gno"), "-o", gnoBin))
+	require.NoError(t, err)
+	// Define script params
+	params := testscript.Params{
+		Setup: func(env *testscript.Env) error {
+			// Envs to have access to gno binary and path in test scripts
+			env.Vars = append(env.Vars,
+				"ROOTDIR="+rootDir,
+				"GNO="+gnoBin,
+			)
+			return nil
+		},
+		// Location of test scripts
+		Dir: "testdata",
+	}
+	// Run test scripts
+	testscript.Run(t, params)
+}

gnovm/tests/testdata/error_correct.txt

@@ -0,0 +1,18 @@
+# Test Error instruction correct
+
+exec $GNO test -verbose -root-dir=$ROOTDIR .
+
+stdout 'Machine\.RunMain\(\) panic: oups'
+stderr '=== RUN   file/x_filetest.gno'
+stderr '--- PASS: file/x_filetest.gno \(\d\.\d\ds\)'
+stderr 'ok      \./\. 	\d\.\d\ds'
+
+-- x_filetest.gno --
+package main
+
+func main() {
+	panic("oups")
+}
+
+// Error:
+// oups

gnovm/tests/testdata/error_incorrect.txt

@@ -0,0 +1,17 @@
+# Test Error instruction incorrect
+
+! exec $GNO test -verbose -root-dir=$ROOTDIR .
+
+stdout 'Machine\.RunMain\(\) panic: oups'
+stderr '=== RUN   file/x_filetest.gno'
+stderr 'panic: fail on x_filetest.gno: got "oups", want: "xxx"'
+
+-- x_filetest.gno --
+package main
+
+func main() {
+	panic("oups")
+}
+
+// Error:
+// xxx

gnovm/tests/testdata/error_sync.txt

@@ -0,0 +1,29 @@
+# Test Error instruction updated
+# NOTE: unlike Output and Realm instruction updates, Error update is not driven
+# by the '-update-golden-tests' flag. The Error is only updated when it is
+# empty.
+
+! exec $GNO test -verbose -root-dir=$ROOTDIR .
+
+cmp x_filetest.gno x_filetest.gno.golden
+
+-- x_filetest.gno --
+package main
+
+func main() {
+	panic("oups")
+}
+
+// Error:
+
+-- x_filetest.gno.golden --
+package main
+
+func main() {
+	panic("oups")
+}
+
+// Error:
+// oups
+// *** CHECK THE ERR MESSAGES ABOVE, MAKE SURE IT'S WHAT YOU EXPECTED, DELETE THIS LINE AND RUN TEST AGAIN ***
+

gnovm/tests/testdata/output_correct.txt

@@ -0,0 +1,20 @@
+# Test Output instruction correct
+
+exec $GNO test -verbose -root-dir=$ROOTDIR .
+
+! stdout .+
+stderr '=== RUN   file/x_filetest.gno'
+stderr '--- PASS: file/x_filetest.gno \(\d\.\d\ds\)'
+stderr 'ok      \./\. 	\d\.\d\ds'
+
+-- x_filetest.gno --
+package main
+
+func main() {
+	println("hey")
+	println("hru?")
+}
+
+// Output:
+// hey
+// hru?

gnovm/tests/testdata/output_incorrect.txt

@@ -0,0 +1,23 @@
+# Test Output instruction incorrect
+
+! exec $GNO test -verbose -root-dir=$ROOTDIR .
+
+! stdout .+
+stderr '=== RUN   file/x_filetest.gno'
+stderr 'panic: fail on x_filetest.gno: diff:'
+stderr '--- Expected'
+stderr '\+\+\+ Actual'
+stderr '@@ -1,2 \+1 @@'
+stderr 'hey'
+stderr '-hru?'
+
+-- x_filetest.gno --
+package main
+
+func main() {
+	println("hey")
+}
+
+// Output:
+// hey
+// hru?

gnovm/tests/testdata/output_sync.txt

@@ -0,0 +1,29 @@
+# Test Output instruction updated
+
+exec $GNO test -verbose -root-dir=$ROOTDIR . -update-golden-tests
+
+cmp x_filetest.gno x_filetest.gno.golden
+
+-- x_filetest.gno --
+package main
+
+func main() {
+	println("hey")
+	println("hru?")
+}
+
+// Output:
+// hey
+
+-- x_filetest.gno.golden --
+package main
+
+func main() {
+	println("hey")
+	println("hru?")
+}
+
+// Output:
+// hey
+// hru?
+

gnovm/tests/testdata/realm_correct.txt

@@ -0,0 +1,85 @@
+# Test Realm instruction correct
+
+exec $GNO test -verbose -root-dir=$ROOTDIR .
+
+! stdout .+
+stderr '=== RUN   file/x_filetest.gno'
+stderr '--- PASS: file/x_filetest.gno \(\d\.\d\ds\)'
+stderr 'ok      \./\. 	\d\.\d\ds'
+
+-- x_filetest.gno --
+// PKGPATH: gno.land/r/x
+package x
+
+var x int
+
+func main() {
+	x = 1
+}
+
+// Realm:
+// switchrealm["gno.land/r/x"]
+// u[58cde29876a8d185e30c727361981efb068f4726:2]={
+//     "Blank": {},
+//     "ObjectInfo": {
+//         "ID": "58cde29876a8d185e30c727361981efb068f4726:2",
+//         "IsEscaped": true,
+//         "ModTime": "3",
+//         "RefCount": "2"
+//     },
+//     "Parent": null,
+//     "Source": {
+//         "@type": "/gno.RefNode",
+//         "BlockNode": null,
+//         "Location": {
+//             "File": "",
+//             "Line": "0",
+//             "Nonce": "0",
+//             "PkgPath": "gno.land/r/x"
+//         }
+//     },
+//     "Values": [
+//         {
+//             "T": {
+//                 "@type": "/gno.FuncType",
+//                 "Params": [],
+//                 "Results": []
+//             },
+//             "V": {
+//                 "@type": "/gno.FuncValue",
+//                 "Closure": {
+//                     "@type": "/gno.RefValue",
+//                     "Escaped": true,
+//                     "ObjectID": "58cde29876a8d185e30c727361981efb068f4726:3"
+//                 },
+//                 "FileName": "main.gno",
+//                 "IsMethod": false,
+//                 "Name": "main",
+//                 "PkgPath": "gno.land/r/x",
+//                 "Source": {
+//                     "@type": "/gno.RefNode",
+//                     "BlockNode": null,
+//                     "Location": {
+//                         "File": "main.gno",
+//                         "Line": "6",
+//                         "Nonce": "0",
+//                         "PkgPath": "gno.land/r/x"
+//                     }
+//                 },
+//                 "Type": {
+//                     "@type": "/gno.FuncType",
+//                     "Params": [],
+//                     "Results": []
+//                 }
+//             }
+//         },
+//         {
+//             "N": "AQAAAAAAAAA=",
+//             "T": {
+//                 "@type": "/gno.PrimitiveType",
+//                 "value": "32"
+//             }
+//         }
+//     ]
+// }
+

gnovm/tests/testdata/realm_incorrect.txt

@@ -0,0 +1,26 @@
+# Test Realm instruction incorrect
+
+! exec $GNO test -verbose -root-dir=$ROOTDIR .
+
+! stdout .+
+stderr '=== RUN   file/x_filetest.gno'
+stderr 'panic: fail on x_filetest.gno: diff:'
+stderr '--- Expected'
+stderr '\+\+\+ Actual'
+stderr '@@ -1 \+1,64 @@'
+stderr '-xxx'
+stderr '\+switchrealm\["gno.land/r/x"\]'
+
+-- x_filetest.gno --
+// PKGPATH: gno.land/r/x
+package x
+
+var x int
+
+func main() {
+	x = 1
+}
+
+// Realm:
+// xxxx
+