[Fix] Recreate missing system schema (#4068)

## Changes

Addresses
#4066.
Makes read function more in line with rest of module to ignore non
`enabled` schemas.

## Tests
<!-- 
How is this tested? Please see the checklist below and also describe any
other relevant tests
-->

- [x] `make test` run locally
- [ ] ~relevant change in `docs/` folder~
- [ ] covered with integration tests in `internal/acceptance`
- [x] relevant acceptance tests are passing
- [ ] ~using Go SDK~

---------

Co-authored-by: wai Lau <[email protected]>
Co-authored-by: Alex Ott <[email protected]>

catalog/resource_system_schema.go

@@ -93,10 +93,21 @@ func ResourceSystemSchema() common.Resource {
 					if err != nil {
 						return err
 					}
+					// only track enabled/legacy schemas
+					if schema.State != catalog.SystemSchemaInfoStateEnableCompleted &&
+						schema.State != catalog.SystemSchemaInfoStateEnableInitialized &&
+						schema.State != catalog.SystemSchemaInfoStateUnavailable {
+						log.Printf("[WARN] %s is not enabled, ignoring it", schemaName)
+						d.SetId("")
+						return nil
+					}
+
 					d.Set("full_name", fmt.Sprintf("system.%s", schemaName))
 					return nil
 				}
 			}
+			log.Printf("[WARN] %s does not exist, ignoring it", schemaName)
+			d.SetId("")
 			return nil
 		},
 		Update: createOrUpdate,

catalog/resource_system_schema_test.go

@@ -239,6 +239,74 @@ func TestSystemSchemaRead_Error(t *testing.T) {
 	assert.Equal(t, "abc|access", d.Id(), "Id should not be empty for error reads")
 }
 
+func TestSystemSchemaRead_NotEnabled(t *testing.T) {
+	d, err := qa.ResourceFixture{
+		Fixtures: []qa.HTTPFixture{
+			{
+				Method:   http.MethodGet,
+				Resource: "/api/2.1/unity-catalog/metastore_summary",
+				Response: catalog.GetMetastoreSummaryResponse{
+					MetastoreId: "abc",
+				},
+			},
+			{
+				Method:   http.MethodGet,
+				Resource: "/api/2.1/unity-catalog/metastores/abc/systemschemas?",
+				Response: catalog.ListSystemSchemasResponse{
+					Schemas: []catalog.SystemSchemaInfo{
+						{
+							Schema: "access",
+							State:  catalog.SystemSchemaInfoStateAvailable,
+						},
+						{
+							Schema: "billing",
+							State:  catalog.SystemSchemaInfoStateEnableCompleted,
+						},
+					},
+				},
+			},
+		},
+		Resource: ResourceSystemSchema(),
+		Read:     true,
+		Removed:  true,
+		ID:       "abc|access",
+	}.Apply(t)
+	assert.NoError(t, err)
+	assert.Equal(t, "", d.Id(), "Id should be empty if a schema is not enabled")
+}
+
+func TestSystemSchemaRead_NotExists(t *testing.T) {
+	d, err := qa.ResourceFixture{
+		Fixtures: []qa.HTTPFixture{
+			{
+				Method:   http.MethodGet,
+				Resource: "/api/2.1/unity-catalog/metastore_summary",
+				Response: catalog.GetMetastoreSummaryResponse{
+					MetastoreId: "abc",
+				},
+			},
+			{
+				Method:   http.MethodGet,
+				Resource: "/api/2.1/unity-catalog/metastores/abc/systemschemas?",
+				Response: catalog.ListSystemSchemasResponse{
+					Schemas: []catalog.SystemSchemaInfo{
+						{
+							Schema: "billing",
+							State:  catalog.SystemSchemaInfoStateEnableCompleted,
+						},
+					},
+				},
+			},
+		},
+		Resource: ResourceSystemSchema(),
+		Read:     true,
+		Removed:  true,
+		ID:       "abc|access",
+	}.Apply(t)
+	assert.NoError(t, err)
+	assert.Equal(t, "", d.Id(), "Id should be empty if a schema does not exist")
+}
+
 func TestSystemSchemaDelete(t *testing.T) {
 	d, err := qa.ResourceFixture{
 		Fixtures: []qa.HTTPFixture{