codegen: add generator for soft-deletion

pkg/codegen/modelgenerate/generate_testfile.go

@@ -69,9 +69,11 @@ func SampleValue(c pkgschema.Column, offset int) ast.Expr {
 // UpdateTestFields returns the columns for which the test generator should assign its own
 // sample values, in the MakeXyz() factory and in the create/update test: the same columns
 // that GenerateSaveItemFunc's "update" branch writes to, minus foreign keys (which can't be
-// given plausible values here) and the auto-managed "created_at"/"updated_at" columns.
+// given plausible values here), the auto-managed "created_at"/"updated_at" columns, and the
+// soft-delete columns (which SoftDeleteXyz() manages).
 func UpdateTestFields(tbl pkgschema.Table) (ret []pkgschema.Column) {
 	hasCreatedAt, hasUpdatedAt := tbl.HasAutoTimestamps()
+	hasSoftDelete := tbl.HasSoftDelete()
 	for _, c := range tbl.Columns {
 		if c.Name == "rowid" || c.IsPrimaryKey || c.IsForeignKey {
 			continue
@@ -82,6 +84,9 @@ func UpdateTestFields(tbl pkgschema.Table) (ret []pkgschema.Column) {
 		if c.Name == "updated_at" && hasUpdatedAt {
 			continue
 		}
+		if hasSoftDelete && (c.Name == "is_deleted" || c.Name == "deleted_at") {
+			continue
+		}
 		ret = append(ret, c)
 	}
 	return