Add identity templating helper to sdk/framework (#8088)

* Add identity templating helper to sdk/framework

* Cleanup a bit

* Fix length issue when groups/aliases are filtered due to ns

* review feedback

sdk/framework/identity_test.go

@@ -0,0 +1,100 @@
+package framework
+
+import (
+	"testing"
+
+	"github.com/hashicorp/vault/sdk/logical"
+)
+
+func TestIdentityTemplating(t *testing.T) {
+	sysView := &logical.StaticSystemView{
+		EntityVal: &logical.Entity{
+			ID:   "test-id",
+			Name: "test",
+			Aliases: []*logical.Alias{
+				{
+					ID:            "alias-id",
+					Name:          "test alias",
+					MountAccessor: "test_mount",
+					MountType:     "secret",
+					Metadata: map[string]string{
+						"alias-metadata": "alias-metadata-value",
+					},
+				},
+			},
+			Metadata: map[string]string{
+				"entity-metadata": "entity-metadata-value",
+			},
+		},
+		GroupsVal: []*logical.Group{
+			{
+				ID:   "group1-id",
+				Name: "group1",
+				Metadata: map[string]string{
+					"group-metadata": "group-metadata-value",
+				},
+			},
+		},
+	}
+
+	tCases := []struct {
+		tpl      string
+		expected string
+	}{
+		{
+			tpl:      "{{identity.entity.id}}",
+			expected: "test-id",
+		},
+		{
+			tpl:      "{{identity.entity.name}}",
+			expected: "test",
+		},
+		{
+			tpl:      "{{identity.entity.metadata.entity-metadata}}",
+			expected: "entity-metadata-value",
+		},
+		{
+			tpl:      "{{identity.entity.aliases.test_mount.id}}",
+			expected: "alias-id",
+		},
+		{
+			tpl:      "{{identity.entity.aliases.test_mount.id}}",
+			expected: "alias-id",
+		},
+		{
+			tpl:      "{{identity.entity.aliases.test_mount.name}}",
+			expected: "test alias",
+		},
+		{
+			tpl:      "{{identity.entity.aliases.test_mount.metadata.alias-metadata}}",
+			expected: "alias-metadata-value",
+		},
+		{
+			tpl:      "{{identity.groups.ids.group1-id.name}}",
+			expected: "group1",
+		},
+		{
+			tpl:      "{{identity.groups.names.group1.id}}",
+			expected: "group1-id",
+		},
+		{
+			tpl:      "{{identity.groups.names.group1.metadata.group-metadata}}",
+			expected: "group-metadata-value",
+		},
+		{
+			tpl:      "{{identity.groups.ids.group1-id.metadata.group-metadata}}",
+			expected: "group-metadata-value",
+		},
+	}
+
+	for _, tCase := range tCases {
+		out, err := PopulateIdentityTemplate(tCase.tpl, "test", sysView)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if out != tCase.expected {
+			t.Fatalf("got %q, expected %q", out, tCase.expected)
+		}
+	}
+}