feat(mssql): add MSSQL writer for generating DDL from database schema

- Implement MSSQL writer to generate SQL scripts for creating schemas, tables, and constraints.
- Support for identity columns, indexes, and extended properties.
- Add tests for column definitions, table creation, primary keys, foreign keys, and comments.
- Include testing guide and sample schema for integration tests.

pkg/writers/mssql/writer_test.go

@@ -0,0 +1,205 @@
+package mssql
+
+import (
+	"bytes"
+	"testing"
+
+	"git.warky.dev/wdevs/relspecgo/pkg/models"
+	"git.warky.dev/wdevs/relspecgo/pkg/writers"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestGenerateColumnDefinition tests column definition generation
+func TestGenerateColumnDefinition(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	tests := []struct {
+		name     string
+		column   *models.Column
+		expected string
+	}{
+		{
+			name: "INT NOT NULL",
+			column: &models.Column{
+				Name:     "id",
+				Type:     "int",
+				NotNull:  true,
+				Sequence: 1,
+			},
+			expected: "[id] INT NOT NULL",
+		},
+		{
+			name: "VARCHAR with length",
+			column: &models.Column{
+				Name:     "name",
+				Type:     "string",
+				Length:   100,
+				NotNull:  true,
+				Sequence: 2,
+			},
+			expected: "[name] NVARCHAR(100) NOT NULL",
+		},
+		{
+			name: "DATETIME2 with default",
+			column: &models.Column{
+				Name:     "created_at",
+				Type:     "timestamp",
+				NotNull:  true,
+				Default:  "GETDATE()",
+				Sequence: 3,
+			},
+			expected: "[created_at] DATETIME2 NOT NULL DEFAULT GETDATE()",
+		},
+		{
+			name: "IDENTITY column",
+			column: &models.Column{
+				Name:          "id",
+				Type:          "int",
+				AutoIncrement: true,
+				NotNull:       true,
+				Sequence:      1,
+			},
+			expected: "[id] INT IDENTITY(1,1) NOT NULL",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := writer.generateColumnDefinition(tt.column)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+// TestWriteCreateTable tests CREATE TABLE statement generation
+func TestWriteCreateTable(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	// Create a test schema with a table
+	schema := models.InitSchema("dbo")
+	table := models.InitTable("users", "dbo")
+
+	col1 := models.InitColumn("id", "users", "dbo")
+	col1.Type = "int"
+	col1.AutoIncrement = true
+	col1.NotNull = true
+	col1.Sequence = 1
+
+	col2 := models.InitColumn("email", "users", "dbo")
+	col2.Type = "string"
+	col2.Length = 255
+	col2.NotNull = true
+	col2.Sequence = 2
+
+	table.Columns["id"] = col1
+	table.Columns["email"] = col2
+
+	// Write to buffer
+	buf := &bytes.Buffer{}
+	writer.writer = buf
+
+	err := writer.writeCreateTable(schema, table)
+	assert.NoError(t, err)
+
+	output := buf.String()
+	assert.Contains(t, output, "CREATE TABLE [dbo].[users]")
+	assert.Contains(t, output, "[id] INT IDENTITY(1,1) NOT NULL")
+	assert.Contains(t, output, "[email] NVARCHAR(255) NOT NULL")
+}
+
+// TestWritePrimaryKey tests PRIMARY KEY constraint generation
+func TestWritePrimaryKey(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	schema := models.InitSchema("dbo")
+	table := models.InitTable("users", "dbo")
+
+	// Add primary key constraint
+	pk := models.InitConstraint("PK_users_id", models.PrimaryKeyConstraint)
+	pk.Columns = []string{"id"}
+	table.Constraints[pk.Name] = pk
+
+	// Add column
+	col := models.InitColumn("id", "users", "dbo")
+	col.Type = "int"
+	col.Sequence = 1
+	table.Columns["id"] = col
+
+	// Write to buffer
+	buf := &bytes.Buffer{}
+	writer.writer = buf
+
+	err := writer.writePrimaryKey(schema, table)
+	assert.NoError(t, err)
+
+	output := buf.String()
+	assert.Contains(t, output, "ALTER TABLE [dbo].[users]")
+	assert.Contains(t, output, "PRIMARY KEY")
+	assert.Contains(t, output, "[id]")
+}
+
+// TestWriteForeignKey tests FOREIGN KEY constraint generation
+func TestWriteForeignKey(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	schema := models.InitSchema("dbo")
+	table := models.InitTable("orders", "dbo")
+
+	// Add foreign key constraint
+	fk := models.InitConstraint("FK_orders_users", models.ForeignKeyConstraint)
+	fk.Columns = []string{"user_id"}
+	fk.ReferencedSchema = "dbo"
+	fk.ReferencedTable = "users"
+	fk.ReferencedColumns = []string{"id"}
+	fk.OnDelete = "CASCADE"
+	fk.OnUpdate = "NO ACTION"
+	table.Constraints[fk.Name] = fk
+
+	// Add column
+	col := models.InitColumn("user_id", "orders", "dbo")
+	col.Type = "int"
+	col.Sequence = 1
+	table.Columns["user_id"] = col
+
+	// Write to buffer
+	buf := &bytes.Buffer{}
+	writer.writer = buf
+
+	err := writer.writeForeignKeys(schema, table)
+	assert.NoError(t, err)
+
+	output := buf.String()
+	assert.Contains(t, output, "ALTER TABLE [dbo].[orders]")
+	assert.Contains(t, output, "FK_orders_users")
+	assert.Contains(t, output, "FOREIGN KEY")
+	assert.Contains(t, output, "CASCADE")
+	assert.Contains(t, output, "NO ACTION")
+}
+
+// TestWriteComments tests extended property generation for comments
+func TestWriteComments(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	schema := models.InitSchema("dbo")
+	table := models.InitTable("users", "dbo")
+	table.Description = "User accounts table"
+
+	col := models.InitColumn("id", "users", "dbo")
+	col.Type = "int"
+	col.Description = "Primary key"
+	col.Sequence = 1
+	table.Columns["id"] = col
+
+	// Write to buffer
+	buf := &bytes.Buffer{}
+	writer.writer = buf
+
+	err := writer.writeComments(schema, table)
+	assert.NoError(t, err)
+
+	output := buf.String()
+	assert.Contains(t, output, "sp_addextendedproperty")
+	assert.Contains(t, output, "MS_Description")
+	assert.Contains(t, output, "User accounts table")
+	assert.Contains(t, output, "Primary key")
+}