feat: add observed Instance extension support checks

internal/domain/instance/extensions_test.go

@@ -0,0 +1,107 @@
+/*
+Copyright 2026.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package instance_test
+
+import (
+	"slices"
+	"testing"
+
+	"git.ddupan.top/panxiao81/postgresql-tenant-operator/internal/domain/instance"
+)
+
+const (
+	testUUID    = "uuid-ossp"
+	testTrigram = "pg_trgm"
+	testVector  = "vector"
+	testChanged = "changed"
+)
+
+// Acceptance: docs/domain-instance.md, extension support is based on observations,
+// not a name regexp or an administrator allowlist.
+func TestExtensionSupportDecisions(t *testing.T) {
+	available := instance.ObserveExtensionSupport([]string{testTrigram, testUUID})
+	cases := []struct {
+		name        string
+		support     instance.ExtensionSupport
+		requested   []string
+		want        instance.ExtensionDecision
+		unsupported []string
+	}{
+		{"unobserved", instance.ExtensionSupport{}, []string{testTrigram}, instance.ExtensionSupportUnobserved, nil},
+		{"observed empty", instance.ObserveExtensionSupport(nil), []string{testTrigram}, instance.ExtensionsUnsupported, []string{testTrigram}},
+		{"empty request", instance.ExtensionSupport{}, nil, instance.ExtensionsAccepted, nil},
+		{"supported", available, []string{testUUID, testTrigram, testTrigram}, instance.ExtensionsAccepted, nil},
+		{"unsupported", available, []string{testVector, "hstore", testVector, testTrigram},
+			instance.ExtensionsUnsupported, []string{"hstore", testVector}},
+		{"exact names", available, []string{"PG_TRGM"}, instance.ExtensionsUnsupported, []string{"PG_TRGM"}},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			result := tc.support.Check(instance.NewExtensionSet(tc.requested))
+			if result.Decision != tc.want || !slices.Equal(result.Unsupported, tc.unsupported) {
+				t.Fatalf("Check() = %v, want %v / %v", result, tc.want, tc.unsupported)
+			}
+		})
+	}
+}
+
+func TestExtensionSetCopiesAndCanonicalizesNames(t *testing.T) {
+	input := []string{testUUID, testTrigram, testUUID}
+	set := instance.NewExtensionSet(input)
+	input[0] = testChanged
+	names := set.Names()
+	want := []string{testTrigram, testUUID}
+	if !slices.Equal(names, want) {
+		t.Fatalf("Names() = %v, want %v", names, want)
+	}
+	names[0] = testChanged
+	if !slices.Equal(set.Names(), want) {
+		t.Fatal("returned slice mutated set")
+	}
+	if len((instance.ExtensionSet{}).Names()) != 0 {
+		t.Fatal("zero set must be empty")
+	}
+	// Names are preserved exactly; actual server support, not a local regexp, is decisive.
+	unusual := []string{"Vendor.Extension", testUUID}
+	if result := instance.ObserveExtensionSupport(unusual).Check(instance.NewExtensionSet(unusual)); result.Decision != instance.ExtensionsAccepted {
+		t.Fatal("imposed a local name restriction")
+	}
+}
+
+func TestExtensionSupportCopiesObservationAndResults(t *testing.T) {
+	input := []string{testTrigram}
+	support := instance.ObserveExtensionSupport(input)
+	input[0] = testVector
+	requested := instance.NewExtensionSet([]string{testTrigram, testVector})
+	result := support.Check(requested)
+	if !slices.Equal(result.Unsupported, []string{testVector}) {
+		t.Fatal("input mutation changed observation")
+	}
+	result.Unsupported[0] = testChanged
+	again := support.Check(requested)
+	if !slices.Equal(again.Unsupported, []string{testVector}) {
+		t.Fatal("result mutation changed subsequent decision")
+	}
+	// Replacing an observation does not mutate the old value or produce uninstall actions.
+	empty := instance.ObserveExtensionSupport(nil)
+	if empty.Check(requested).Decision != instance.ExtensionsUnsupported {
+		t.Fatal("empty observation ignored")
+	}
+	if support.Check(instance.NewExtensionSet([]string{testTrigram})).Decision != instance.ExtensionsAccepted {
+		t.Fatal("new observation mutated old value")
+	}
+}