Add tests for tables/columns with comments

Cover the cases:
* a column with a comment is added via a create table migration
* a column with a comment is added via an add column migration.
* A new table is added with a comment on the table itself.

pkg/migrations/op_add_column_test.go

@@ -47,6 +47,7 @@ func TestAddColumn(t *testing.T) {
 							Type:     "integer",
 							Nullable: false,
 							Default:  ptr("0"),
+							Comment:  ptr("the age of the user"),
 						},
 					},
 				},
@@ -751,3 +752,59 @@ func TestAddColumnWithCheckConstraint(t *testing.T) {
 		},
 	}})
 }
+
+func TestAddColumnWithComment(t *testing.T) {
+	t.Parallel()
+
+	ExecuteTests(t, TestCases{{
+		name: "add column",
+		migrations: []migrations.Migration{
+			{
+				Name: "01_add_table",
+				Operations: migrations.Operations{
+					&migrations.OpCreateTable{
+						Name: "users",
+						Columns: []migrations.Column{
+							{
+								Name: "id",
+								Type: "serial",
+								Pk:   true,
+							},
+							{
+								Name:   "name",
+								Type:   "varchar(255)",
+								Unique: true,
+							},
+						},
+					},
+				},
+			},
+			{
+				Name: "02_add_column",
+				Operations: migrations.Operations{
+					&migrations.OpAddColumn{
+						Table: "users",
+						Column: migrations.Column{
+							Name:     "age",
+							Type:     "integer",
+							Nullable: false,
+							Default:  ptr("0"),
+							Comment:  ptr("the age of the user"),
+						},
+					},
+				},
+			},
+		},
+		afterStart: func(t *testing.T, db *sql.DB) {
+			// The comment has been added to the underlying column.
+			columnName := migrations.TemporaryName("age")
+			ColumnMustHaveComment(t, db, "public", "users", columnName, "the age of the user")
+		},
+		afterRollback: func(t *testing.T, db *sql.DB) {
+		},
+		afterComplete: func(t *testing.T, db *sql.DB) {
+			// The comment is still present on the underlying column.
+			ColumnMustHaveComment(t, db, "public", "users", "age", "the age of the user")
+		},
+	}})
+}

pkg/migrations/op_common_test.go

@@ -146,6 +146,20 @@ func ColumnMustHaveType(t *testing.T, db *sql.DB, schema, table, column, expecte
 	}
 }
 
+func ColumnMustHaveComment(t *testing.T, db *sql.DB, schema, table, column, expectedComment string) {
+	t.Helper()
+	if !columnHasComment(t, db, schema, table, column, expectedComment) {
+		t.Fatalf("Expected column %q to have comment %q", column, expectedComment)
+	}
+}
+
+func TableMustHaveComment(t *testing.T, db *sql.DB, schema, table, expectedComment string) {
+	t.Helper()
+	if !tableHasComment(t, db, schema, table, expectedComment) {
+		t.Fatalf("Expected table %q to have comment %q", table, expectedComment)
+	}
+}
+
 func TableMustHaveColumnCount(t *testing.T, db *sql.DB, schema, table string, n int) {
 	t.Helper()
 	if !tableMustHaveColumnCount(t, db, schema, table, n) {
@@ -400,6 +414,40 @@ func columnHasType(t *testing.T, db *sql.DB, schema, table, column, expectedType
 	return expectedType == actualType
 }
 
+func columnHasComment(t *testing.T, db *sql.DB, schema, table, column, expectedComment string) bool {
+	t.Helper()
+
+	var actualComment string
+	err := db.QueryRow(fmt.Sprintf(`
+    SELECT col_description(
+      %[1]s::regclass,
+      (SELECT attnum FROM pg_attribute WHERE attname=%[2]s and attrelid=%[1]s::regclass)
+    )`,
+		pq.QuoteLiteral(fmt.Sprintf("%s.%s", schema, table)),
+		pq.QuoteLiteral(column)),
+	).Scan(&actualComment)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return expectedComment == actualComment
+}
+
+func tableHasComment(t *testing.T, db *sql.DB, schema, table, expectedComment string) bool {
+	t.Helper()
+
+	var actualComment string
+	err := db.QueryRow(fmt.Sprintf(`
+    SELECT obj_description(%[1]s::regclass, 'pg_class')`,
+		pq.QuoteLiteral(fmt.Sprintf("%s.%s", schema, table))),
+	).Scan(&actualComment)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return expectedComment == actualComment
+}
+
 func MustInsert(t *testing.T, db *sql.DB, schema, version, table string, record map[string]string) {
 	t.Helper()
 

pkg/migrations/op_create_table_test.go

@@ -230,6 +230,48 @@ func TestCreateTable(t *testing.T) {
 				})
 			},
 		},
+		{
+			name: "create table with column and table comments",
+			migrations: []migrations.Migration{
+				{
+					Name: "01_create_table",
+					Operations: migrations.Operations{
+						&migrations.OpCreateTable{
+							Name:    "users",
+							Comment: ptr("the users table"),
+							Columns: []migrations.Column{
+								{
+									Name: "id",
+									Type: "serial",
+									Pk:   true,
+								},
+								{
+									Name:    "name",
+									Type:    "varchar(255)",
+									Unique:  true,
+									Comment: ptr("the username"),
+								},
+							},
+						},
+					},
+				},
+			},
+			afterStart: func(t *testing.T, db *sql.DB) {
+				tableName := migrations.TemporaryName("users")
+				// The comment has been added to the underlying table.
+				TableMustHaveComment(t, db, "public", tableName, "the users table")
+				// The comment has been added to the underlying column.
+				ColumnMustHaveComment(t, db, "public", tableName, "name", "the username")
+			},
+			afterRollback: func(t *testing.T, db *sql.DB) {
+			},
+			afterComplete: func(t *testing.T, db *sql.DB) {
+				// The comment is still present on the underlying table.
+				TableMustHaveComment(t, db, "public", "users", "the users table")
+				// The comment is still present on the underlying column.
+				ColumnMustHaveComment(t, db, "public", "users", "name", "the username")
+			},
+		},
 	})
 }