test(agentcompat): add agent runtime harness

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/agent/readiness_version_test.go

@@ -0,0 +1,36 @@
+//go:build linux
+
+package agent
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestHostVersionEvidence_IsNotObserved_whenReportedVersionIsEmpty(t *testing.T) {
+	// Given
+	host := json.RawMessage(`{"version":""}`)
+
+	// When
+	version, observed, err := decodeHostVersionEvidence(host)
+
+	// Then
+	require.NoError(t, err)
+	require.Empty(t, version)
+	require.False(t, observed)
+}
+
+func TestHostVersionEvidence_IsObserved_whenReportedVersionIsNonempty(t *testing.T) {
+	// Given
+	host := json.RawMessage(`{"version":"v2.1.0"}`)
+
+	// When
+	version, observed, err := decodeHostVersionEvidence(host)
+
+	// Then
+	require.NoError(t, err)
+	require.Equal(t, "v2.1.0", version)
+	require.True(t, observed)
+}