refactor: make migration process more intelligent, add test coverage
This commit is contained in:
260
pkg/db/migration_test.go
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260
pkg/db/migration_test.go
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package db_test
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import (
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"testing"
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"github.com/jmoiron/sqlx"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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"git.offline-twitter.com/offline-labs/gas-stack/pkg/db"
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"git.offline-twitter.com/offline-labs/gas-stack/pkg/must"
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)
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// migrationTestSchema has a foreign key (`children.parent_id` => `parents.rowid`) along with one
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// valid parent/child pair, so that migrations can be written which either preserve or break
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// referential integrity.
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var migrationTestSchema = `
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create table db_version (version integer primary key) strict, without rowid;
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insert into db_version values (0);
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create table parents (
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rowid integer primary key,
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name text not null
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);
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insert into parents (rowid, name) values (1, 'p1');
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create table children (
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rowid integer primary key,
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parent_id integer not null references parents(rowid)
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);
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insert into children (rowid, parent_id) values (1, 1);
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`
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func newMigrationTestDB() *sqlx.DB {
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return must.Get(db.Init(&migrationTestSchema, &[]db.Migration{}).Create(":memory:"))
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}
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func assertForeignKeysAreGood(t *testing.T, conn *sqlx.DB) {
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t.Helper()
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// FKs should be enabled and intact at all times
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var fkEnabled bool
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require.NoError(t, conn.Get(&fkEnabled, `pragma foreign_keys`))
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assert.True(t, fkEnabled)
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assert.NoError(t, db.PragmaForeignKeyCheck(conn))
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// ...and enforcement should be in effect again, not merely reported as on
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_, err := conn.Exec(`insert into children (rowid, parent_id) values (99, 40235235234)`)
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assert.True(t, db.IsSqliteFkError(err), "expected a foreign key error, got: %v", err)
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}
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func TestMigrationApply(t *testing.T) {
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conn := newMigrationTestDB()
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testcases := []struct {
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Migration db.Migration
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ExpectedParents int
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ExpectedChildren int
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}{
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{
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Migration: db.Migration{
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ID: 1,
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Title: "add a second parent",
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SQL: `insert into parents (rowid, name) values (2, 'p2')`,
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},
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ExpectedParents: 2,
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ExpectedChildren: 1,
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},
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{
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Migration: db.Migration{ID: 2, SQL: `
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insert into children (rowid, parent_id) values (2, 2);
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insert into parents (rowid, name) values (3, 'p3');
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`},
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ExpectedParents: 3,
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ExpectedChildren: 2,
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},
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}
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for _, tc := range testcases {
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t.Run(tc.Migration.Title, func(t *testing.T) {
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require.NoError(t, tc.Migration.Apply(conn))
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// Check that it applied
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var parents int
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require.NoError(t, conn.Get(&parents, `select count(*) from parents`))
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assert.Equal(t, tc.ExpectedParents, parents)
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var children int
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require.NoError(t, conn.Get(&children, `select count(*) from children`))
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assert.Equal(t, tc.ExpectedChildren, children)
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// Should bump the DB version
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var version int
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require.NoError(t, conn.Get(&version, `select version from db_version`))
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assert.Equal(t, tc.Migration.ID, version, "db version should be bumped to the migration's ID")
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assertForeignKeysAreGood(t, conn)
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})
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}
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}
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// A migration whose SQL fails must leave no trace, including the statements which had already
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// succeeded before the failing one. Every migration below therefore starts by creating
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// `new_table`, which must never survive.
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func TestMigrationFailureRollsBack(t *testing.T) {
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conn := newMigrationTestDB()
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nothingHappens := func(t *testing.T) {
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t.Helper()
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// Everything should be rolled back, including the statements which ran before the failing one
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var newTables int
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require.NoError(t, conn.Get(&newTables, `select count(*) from sqlite_master where type = 'table' and name = 'new_table'`))
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assert.Equal(t, 0, newTables, "the migration's earlier statements should be rolled back too")
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var version int
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require.NoError(t, conn.Get(&version, `select version from db_version`))
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assert.Equal(t, 0, version)
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var parents int
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require.NoError(t, conn.Get(&parents, `select count(*) from parents`))
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assert.Equal(t, 1, parents)
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var children int
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require.NoError(t, conn.Get(&children, `select count(*) from children`))
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assert.Equal(t, 1, children)
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}
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testcases2 := []db.Migration{
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{
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ID: 1,
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Title: "syntax error",
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SQL: `
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create table new_table (rowid integer primary key);
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this is not valid sql;
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`,
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},
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{
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ID: 1,
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Title: "unknown table",
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SQL: `
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create table new_table (rowid integer primary key);
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insert into no_such_table (rowid) values (1);
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`,
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},
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{
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ID: 1,
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Title: "constraint violation",
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SQL: `
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create table new_table (rowid integer primary key);
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insert into parents (rowid, name) values (1, 'duplicate rowid');
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`,
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},
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{
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ID: 1,
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Title: "failure after a successful write",
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SQL: `
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create table new_table (rowid integer primary key);
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insert into parents (rowid, name) values (2, 'p2');
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insert into parents (rowid, name) values (1, 'duplicate rowid');
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`,
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},
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}
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for _, tc := range testcases2 {
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t.Run(tc.Title, func(t *testing.T) {
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assert.Panics(t, func() { _ = tc.Apply(conn) })
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nothingHappens(t)
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assertForeignKeysAreGood(t, conn)
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})
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}
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// ---------
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// Foreign key failures should trigger a rollback too
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// ---------
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testcases := []db.Migration{
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{
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ID: 1,
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Title: "child pointing at a nonexistent parent",
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SQL: `
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create table new_table (rowid integer primary key);
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insert into children (rowid, parent_id) values (2, 404);
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`,
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},
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{
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ID: 1,
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Title: "parent deleted out from under an existing child",
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SQL: `
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create table new_table (rowid integer primary key);
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delete from parents where rowid = 1;
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`,
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},
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}
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for _, tc := range testcases {
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t.Run(tc.Title, func(t *testing.T) {
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// Should notify with the correct detail about the error
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func() {
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defer func() {
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err := recover()
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require.NotNil(t, err)
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switch err := err.(type) {
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case error:
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var violations db.PragmaFKViolations
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require.ErrorAs(t, err, &violations)
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require.Len(t, violations, 1)
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assert.Equal(t, "children", violations[0].SrcTable)
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assert.Equal(t, "parents", violations[0].DstTable)
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default:
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panic(err) // Something weird happened
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}
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}()
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_ = tc.Apply(conn)
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}()
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// ...as well as the usual
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nothingHappens(t)
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assertForeignKeysAreGood(t, conn)
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})
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}
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}
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// Migrations are sequential: a migration may only be applied to a DB sitting at the immediately
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// preceding version.
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func TestMigrationApplyRejectsOutOfOrderMigrations(t *testing.T) {
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const sql = `insert into parents (name) values ('p2')`
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t.Run("migration from the future", func(t *testing.T) {
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conn := newMigrationTestDB()
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err := db.Migration{ID: 2, SQL: sql}.Apply(conn)
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require.ErrorIs(t, err, db.ErrMigrationOrder)
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var version int
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require.NoError(t, conn.Get(&version, `select version from db_version`))
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assert.Equal(t, 0, version)
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var parents int
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require.NoError(t, conn.Get(&parents, `select count(*) from parents`))
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assert.Equal(t, 1, parents, "the migration's SQL should not have run")
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assertForeignKeysAreGood(t, conn)
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})
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t.Run("migration applied twice", func(t *testing.T) {
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conn := newMigrationTestDB()
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m := db.Migration{ID: 1, SQL: sql}
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require.NoError(t, m.Apply(conn))
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err := m.Apply(conn)
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require.ErrorIs(t, err, db.ErrMigrationOrder)
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var version int
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require.NoError(t, conn.Get(&version, `select version from db_version`))
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assert.Equal(t, 1, version)
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var parents int
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require.NoError(t, conn.Get(&parents, `select count(*) from parents`))
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assert.Equal(t, 2, parents, "the migration's SQL should not have run again")
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assertForeignKeysAreGood(t, conn)
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})
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}
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