From 1c566615603587b578680e30ffea80b4b81483a9 Mon Sep 17 00:00:00 2001
From: wispem-wantex <wispem-wantex@playfulpachyderm.com>
Date: Sat, 31 Jan 2026 20:35:03 -0800
Subject: [PATCH] codegen: add foreign key error check test

---
 ops/gas_init_test.sh                          |   6 +-
 pkg/codegen/modelgenerate/generate_model.go   |   2 +-
 .../modelgenerate/generate_testfile.go        | 160 ++++++++++++++++--
 pkg/db/errors_test_helper.go                  |  21 +++
 4 files changed, 172 insertions(+), 17 deletions(-)
 create mode 100644 pkg/db/errors_test_helper.go

diff --git a/ops/gas_init_test.sh b/ops/gas_init_test.sh
index f94ac45..65ddf96 100755
--- a/ops/gas_init_test.sh
+++ b/ops/gas_init_test.sh
@@ -9,7 +9,8 @@ set -e
 set -x
 
 PS4='+(${BASH_SOURCE}:${LINENO}): '
-cd "$(dirname "${BASH_SOURCE[0]}")/.."
+proj_root=$(readlink -f "$(dirname "${BASH_SOURCE[0]}")/..")
+cd "$proj_root"
 
 # Compile `gas`
 gas="/tmp/gas"
@@ -29,6 +30,9 @@ EOF
 
 cd $test_project
 
+# Add "replace" directive"
+echo "replace git.offline-twitter.com/offline-labs/gas-stack => $proj_root" >> go.mod
+
 # Create a new table in the schema
 cat >> pkg/db/schema.sql <<EOF
 create table item_flavor (rowid integer primary key, name text not null) strict;
diff --git a/pkg/codegen/modelgenerate/generate_model.go b/pkg/codegen/modelgenerate/generate_model.go
index fdfbb47..2ee7d86 100644
--- a/pkg/codegen/modelgenerate/generate_model.go
+++ b/pkg/codegen/modelgenerate/generate_model.go
@@ -214,7 +214,7 @@ func GenerateSaveItemFunc(tbl schema.Table) *ast.FuncDecl {
 													&ast.CallExpr{
 														Fun: ast.NewIdent("NewForeignKeyError"),
 														Args: []ast.Expr{
-															ast.NewIdent(`"Type"`),
+															&ast.BasicLit{Kind: token.STRING, Value: fmt.Sprintf("%q", structFieldName)},
 															ast.NewIdent(fmt.Sprintf("%q", col.ForeignKeyTargetTable)),
 															structField,
 														},
diff --git a/pkg/codegen/modelgenerate/generate_testfile.go b/pkg/codegen/modelgenerate/generate_testfile.go
index 9fc9b75..f4d839e 100644
--- a/pkg/codegen/modelgenerate/generate_testfile.go
+++ b/pkg/codegen/modelgenerate/generate_testfile.go
@@ -83,6 +83,30 @@ func GenerateModelTestAST(tbl schema.Table, gomodName string) *ast.File {
 		},
 	}
 
+	// func MakeItem() Item { return Item{} }
+	makeItemFunc := &ast.FuncDecl{
+		Name: ast.NewIdent("Make" + tbl.GoTypeName),
+		Type: &ast.FuncType{
+			Params: &ast.FieldList{},
+			Results: &ast.FieldList{
+				List: []*ast.Field{
+					{Type: ast.NewIdent(tbl.GoTypeName)},
+				},
+			},
+		},
+		Body: &ast.BlockStmt{
+			List: []ast.Stmt{
+				&ast.ReturnStmt{
+					Results: []ast.Expr{
+						&ast.CompositeLit{
+							Type: ast.NewIdent(tbl.GoTypeName),
+						},
+					},
+				},
+			},
+		},
+	}
+
 	testObj := ast.NewIdent("item")
 	testObj2 := ast.NewIdent("item2")
 	fieldName := ast.NewIdent("Description")
@@ -209,7 +233,7 @@ func GenerateModelTestAST(tbl schema.Table, gomodName string) *ast.File {
 					Args: []ast.Expr{
 						ast.NewIdent("t"),
 						ast.NewIdent("err"),
-						&ast.SelectorExpr{X: ast.NewIdent("db"), Sel: ast.NewIdent("ErrNotInDB")},
+						ast.NewIdent("ErrNotInDB"),
 					},
 				}},
 			},
@@ -237,9 +261,126 @@ func GenerateModelTestAST(tbl schema.Table, gomodName string) *ast.File {
 		},
 	}
 
+	shouldIncludeTestFkCheck := false
+	testFkChecking := &ast.FuncDecl{
+		Name: ast.NewIdent("Test" + tbl.GoTypeName + "FkChecking"),
+		Type: &ast.FuncType{
+			Params: &ast.FieldList{
+				List: []*ast.Field{
+					{
+						Names: []*ast.Ident{ast.NewIdent("t")},
+						Type: &ast.StarExpr{
+							X: &ast.SelectorExpr{
+								X:   ast.NewIdent("testing"),
+								Sel: ast.NewIdent("T"),
+							},
+						},
+					},
+				},
+			},
+		},
+		Body: &ast.BlockStmt{
+			List: func() []ast.Stmt {
+				// post := MakePost()
+				stmts := []ast.Stmt{
+					&ast.AssignStmt{
+						Lhs: []ast.Expr{ast.NewIdent(tbl.VarName)},
+						Tok: token.DEFINE,
+						Rhs: []ast.Expr{
+							&ast.CallExpr{
+								Fun: ast.NewIdent("Make" + tbl.GoTypeName),
+							},
+						},
+					},
+				}
+				for _, col := range tbl.Columns {
+					if col.IsForeignKey {
+						shouldIncludeTestFkCheck = true
+						stmts = append(stmts, []ast.Stmt{
+
+							// post.QuotedPostID = 94354538969386985
+							&ast.AssignStmt{
+								Lhs: []ast.Expr{
+									&ast.SelectorExpr{
+										X:   ast.NewIdent(tbl.VarName),
+										Sel: ast.NewIdent(fkFieldName(col)),
+									},
+								},
+								Tok: token.ASSIGN,
+								Rhs: []ast.Expr{
+									&ast.BasicLit{
+										Kind:  token.INT,
+										Value: "94354538969386985",
+									},
+								},
+							},
+
+							// err := db.SavePost(&post)
+							&ast.AssignStmt{
+								Lhs: []ast.Expr{ast.NewIdent("err")},
+								Tok: token.DEFINE,
+								Rhs: []ast.Expr{
+									&ast.CallExpr{
+										Fun: &ast.SelectorExpr{
+											X:   ast.NewIdent("TestDB"),
+											Sel: ast.NewIdent("Save" + tbl.GoTypeName),
+										},
+										Args: []ast.Expr{
+											&ast.UnaryExpr{
+												Op: token.AND,
+												X:  ast.NewIdent(tbl.VarName),
+											},
+										},
+									},
+								},
+							},
+
+							// assertForeignKeyError(t, err, "QuotedPostID", post.QuotedPostID)
+							&ast.ExprStmt{
+								X: &ast.CallExpr{
+									Fun: ast.NewIdent("AssertForeignKeyError"),
+									Args: []ast.Expr{
+										ast.NewIdent("t"),
+										ast.NewIdent("err"),
+										&ast.BasicLit{
+											Kind:  token.STRING,
+											Value: fmt.Sprintf("%q", fkFieldName(col)),
+										},
+										&ast.SelectorExpr{
+											X:   ast.NewIdent(tbl.VarName),
+											Sel: ast.NewIdent(fkFieldName(col)),
+										},
+									},
+								},
+							},
+						}...)
+					}
+				}
+				return stmts
+			}(),
+		},
+	}
+
+	testList := []ast.Decl{
+		// var TestDB *DB
+		testDBDecl,
+		makeItemFunc,
+
+		// func init() { TestDB = MakeDB("tmp") }
+		initFuncDecl,
+
+		// func MakeDB(dbName string) *DB { db := Must(Create(fmt.Sprintf("file:%s?mode=memory&cache=shared", dbName))); return db }
+		makeDBHelperDecl,
+
+		testCreateUpdateDelete,
+		testGetAll,
+	}
+	if shouldIncludeTestFkCheck {
+		testList = append(testList, testFkChecking)
+	}
 	return &ast.File{
 		Name: ast.NewIdent(testpackageName),
-		Decls: []ast.Decl{
+		Decls: append([]ast.Decl{
 			&ast.GenDecl{
 				Tok: token.IMPORT,
 				Specs: []ast.Spec{
@@ -247,7 +388,7 @@ func GenerateModelTestAST(tbl schema.Table, gomodName string) *ast.File {
 					&ast.ImportSpec{Path: &ast.BasicLit{Kind: token.STRING, Value: `"testing"`}},
 					&ast.ImportSpec{
 						Path: &ast.BasicLit{Kind: token.STRING, Value: `"git.offline-twitter.com/offline-labs/gas-stack/pkg/db"`},
-						Name: ast.NewIdent("db"),
+						Name: ast.NewIdent("."),
 					},
 					&ast.ImportSpec{
 						Path: &ast.BasicLit{Kind: token.STRING, Value: `"git.offline-twitter.com/offline-labs/gas-stack/pkg/flowutils"`},
@@ -261,17 +402,6 @@ func GenerateModelTestAST(tbl schema.Table, gomodName string) *ast.File {
 					&ast.ImportSpec{Path: &ast.BasicLit{Kind: token.STRING, Value: `"github.com/stretchr/testify/require"`}},
 				},
 			},
-			// var TestDB *DB
-			testDBDecl,
-
-			// func init() { TestDB = MakeDB("tmp") }
-			initFuncDecl,
-
-			// func MakeDB(dbName string) *DB { db := Must(Create(fmt.Sprintf("file:%s?mode=memory&cache=shared", dbName))); return db }
-			makeDBHelperDecl,
-
-			testCreateUpdateDelete,
-			testGetAll,
-		},
+		}, testList...),
 	}
 }
diff --git a/pkg/db/errors_test_helper.go b/pkg/db/errors_test_helper.go
new file mode 100644
index 0000000..a8512e6
--- /dev/null
+++ b/pkg/db/errors_test_helper.go
@@ -0,0 +1,21 @@
+package db
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func AssertForeignKeyError[T ForeignKey](t *testing.T, err error, field string, val T) {
+	t.Helper()
+
+	var fkErr ForeignKeyError[T]
+	require.Error(t, err)
+	require.ErrorIs(t, err, ErrForeignKeyViolation)
+	// ErrorAs produces terrible error messages if it's a ForeignKeyError with a different type
+	// parameter (i.e., if it was a different field that failed).
+	require.ErrorAs(t, err, &fkErr, "expected error field: %q", field)
+	assert.Equal(t, field, fkErr.Field)
+	assert.Equal(t, val, fkErr.FkValue)
+}