[management] fix posture check flip evaluation for affected peers calc (#7347)

shared/management/networkmap/nmdata/posture.go

@@ -45,6 +45,22 @@ func PassesChecks(checks []Check, peer *Peer) bool {
 	return true
 }
 
+// PostureVerdictChanged reports whether any check in the bundles gives a different
+// verdict for newPeer than for oldPeer. Checks are replayed one by one, so a change
+// that moves a field but stays on the same side of a threshold does not count. An
+// evaluation error is a deny, like in PassesChecks.
+func PostureVerdictChanged(checks []*PostureChecks, oldPeer, newPeer *Peer) bool {
+	for _, pc := range checks {
+		for _, c := range pc.GetChecks() {
+			single := []Check{c}
+			if PassesChecks(single, oldPeer) != PassesChecks(single, newPeer) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 // GetChecks returns the initialized checks in the same order as posture.Checks.GetChecks.
 func (pc *PostureChecks) GetChecks() []Check {
 	var checks []Check

shared/management/networkmap/nmdata/posture_test.go

@@ -0,0 +1,54 @@
+package nmdata
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func bundle(def ChecksDefinition) []*PostureChecks {
+	return []*PostureChecks{{Checks: def}}
+}
+
+func TestPostureVerdictChanged_ErrorCountsAsDeny(t *testing.T) {
+	c := bundle(ChecksDefinition{NBVersionCheck: &NBVersionCheck{MinVersion: "1.2.0"}})
+
+	tests := []struct {
+		name           string
+		oldVer, newVer string
+		want           bool
+	}{
+		{"both above min, no flip", "1.3.0", "1.4.0", false},
+		{"crosses up below->above", "1.1.0", "1.3.0", true},
+		{"unparsable old only -> flip", "garbage", "1.3.0", true},
+		{"unparsable both -> no flip", "garbage", "junk", false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			oldPeer := &Peer{Meta: PeerSystemMeta{WtVersion: tt.oldVer}}
+			newPeer := &Peer{Meta: PeerSystemMeta{WtVersion: tt.newVer}}
+			assert.Equal(t, tt.want, PostureVerdictChanged(c, oldPeer, newPeer))
+		})
+	}
+}
+
+func TestPostureVerdictChanged_ReplaysEachCheck(t *testing.T) {
+	// Old fails the version check, new fails the kernel check: the bundle denies on
+	// both sides, yet every single check flipped, so the posture must be re-evaluated.
+	c := bundle(ChecksDefinition{
+		NBVersionCheck: &NBVersionCheck{MinVersion: "1.0.0"},
+		OSVersionCheck: &OSVersionCheck{Linux: &MinKernelVersionCheck{MinKernelVersion: "5.0.0"}},
+	})
+	oldPeer := &Peer{Meta: PeerSystemMeta{WtVersion: "0.9.0", GoOS: "linux", KernelVersion: "6.0.0"}}
+	newPeer := &Peer{Meta: PeerSystemMeta{WtVersion: "1.1.0", GoOS: "linux", KernelVersion: "4.0.0"}}
+
+	assert.False(t, c[0].Passes(oldPeer))
+	assert.False(t, c[0].Passes(newPeer))
+	assert.True(t, PostureVerdictChanged(c, oldPeer, newPeer))
+}
+
+func TestPostureVerdictChanged_NoChecks(t *testing.T) {
+	oldPeer := &Peer{Meta: PeerSystemMeta{WtVersion: "1.0.0"}}
+	newPeer := &Peer{Meta: PeerSystemMeta{WtVersion: "2.0.0"}}
+	assert.False(t, PostureVerdictChanged(nil, oldPeer, newPeer))
+}