realMachine: a change carrying a lock no release has installed runs with the toolchain installed last, and says so, so a lock change is not refused by its own check (issue 1891, ADR 0533 §3)

modules/mesh-build-node/cmd/mesh-build-node/build_integration_test.go

@@ -12,6 +12,7 @@ import (
 	"path/filepath"
 	"slices"
 	"testing"
+	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/forgekey"
 )
@@ -125,9 +126,10 @@ func TestAPackageWhoseTestsImportItsBuildPassesTheUnitLevel(t *testing.T) {
 	}
 }
 
-// installedToolchain is the toolchain directory under toolchains that this node's Node build module installed from
-// the lock at lockPath, byte for byte; "" when there is none (or the directory cannot be read: no Node build module
-// here). A toolchain of another lock is never taken: the tests prove the lock they carry.
+// installedToolchain is the toolchain directory under toolchains that this node's Node build module installed: the
+// one installed from the lock at lockPath, byte for byte, or, when the change carries a lock no delivered release has
+// installed yet, the one installed last, said in the test's log (ADR 0533 §3: a new lock is proven by the module that
+// installs it on its first node). "" when none is there or the directory cannot be read: no Node build module here.
 func installedToolchain(t *testing.T, toolchains, lockPath string) string {
 	t.Helper()
 	want, err := os.ReadFile(lockPath)
@@ -138,17 +140,29 @@ func installedToolchain(t *testing.T, toolchains, lockPath string) string {
 	if err != nil {
 		return ""
 	}
+	last, lastAt := "", time.Time{}
 	for _, e := range entries {
 		dir := filepath.Join(toolchains, e.Name())
-		if _, err := os.Stat(filepath.Join(dir, installedMark)); err != nil {
+		mark, err := os.Stat(filepath.Join(dir, installedMark))
+		if err != nil {
 			continue
 		}
-		if got, err := os.ReadFile(filepath.Join(dir, "package-lock.json")); err == nil && bytes.Equal(got, want) {
-			t.Logf("the toolchain is this node's installed %s", dir)
+		got, err := os.ReadFile(filepath.Join(dir, "package-lock.json"))
+		if err != nil {
+			continue
+		}
+		if bytes.Equal(got, want) {
+			t.Logf("the toolchain is this node's installed %s, of this change's lock", dir)
 			return dir
 		}
+		if mark.ModTime().After(lastAt) {
+			last, lastAt = dir, mark.ModTime()
+		}
 	}
-	return ""
+	if last != "" {
+		t.Logf("NOT THIS LOCK: no toolchain of this change's lock is installed here; the tests run with the one installed last, %s", last)
+	}
+	return last
 }
 
 // copyToolchain copies the installed toolchain from into to whole, files and folders with their modes, so the test's