Add MimeMessage builder and unit tests

Author: stevebauman

src/Support/MimeMessage.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace DirectoryTree\ImapEngine\Support;
+
+use DirectoryTree\ImapEngine\BodyStructurePart;
+
+class MimeMessage
+{
+    /**
+     * Build a minimal MIME message from body structure metadata and raw content.
+     */
+    public static function make(BodyStructurePart $part, string $content): string
+    {
+        $headers = ["Content-Type: {$part->contentType()}"];
+
+        if ($charset = $part->charset()) {
+            $headers[0] .= "; charset=\"{$charset}\"";
+        }
+
+        if ($encoding = $part->encoding()) {
+            $headers[] = "Content-Transfer-Encoding: {$encoding}";
+        }
+
+        return implode("\r\n", $headers)."\r\n\r\n".$content;
+    }
+}

tests/Unit/MimeMessageTest.php

@@ -0,0 +1,85 @@
+<?php
+
+use DirectoryTree\ImapEngine\BodyStructurePart;
+use DirectoryTree\ImapEngine\Support\MimeMessage;
+
+test('it builds mime message with content type', function () {
+    $part = new BodyStructurePart(
+        partNumber: '1',
+        type: 'text',
+        subtype: 'plain',
+    );
+
+    $mime = MimeMessage::make($part, 'Hello World!');
+
+    expect($mime)->toBe("Content-Type: text/plain\r\n\r\nHello World!");
+});
+
+test('it builds mime message with charset', function () {
+    $part = new BodyStructurePart(
+        partNumber: '1',
+        type: 'text',
+        subtype: 'plain',
+        parameters: ['charset' => 'utf-8'],
+    );
+
+    $mime = MimeMessage::make($part, 'Hello World!');
+
+    expect($mime)->toBe("Content-Type: text/plain; charset=\"utf-8\"\r\n\r\nHello World!");
+});
+
+test('it builds mime message with transfer encoding', function () {
+    $part = new BodyStructurePart(
+        partNumber: '1',
+        type: 'text',
+        subtype: 'plain',
+        encoding: 'base64',
+    );
+
+    $mime = MimeMessage::make($part, 'SGVsbG8gV29ybGQh');
+
+    expect($mime)->toBe("Content-Type: text/plain\r\nContent-Transfer-Encoding: base64\r\n\r\nSGVsbG8gV29ybGQh");
+});
+
+test('it builds mime message with charset and transfer encoding', function () {
+    $part = new BodyStructurePart(
+        partNumber: '1',
+        type: 'text',
+        subtype: 'plain',
+        parameters: ['charset' => 'utf-8'],
+        encoding: 'quoted-printable',
+    );
+
+    $mime = MimeMessage::make($part, 'Hello=20World!');
+
+    expect($mime)->toBe("Content-Type: text/plain; charset=\"utf-8\"\r\nContent-Transfer-Encoding: quoted-printable\r\n\r\nHello=20World!");
+});
+
+test('it builds mime message for html content', function () {
+    $part = new BodyStructurePart(
+        partNumber: '1',
+        type: 'text',
+        subtype: 'html',
+        parameters: ['charset' => 'utf-8'],
+        encoding: '7bit',
+    );
+
+    $mime = MimeMessage::make($part, '<p>Hello World!</p>');
+
+    expect($mime)->toBe("Content-Type: text/html; charset=\"utf-8\"\r\nContent-Transfer-Encoding: 7bit\r\n\r\n<p>Hello World!</p>");
+});
+
+test('it builds mime message with iso-8859-1 charset', function () {
+    $part = new BodyStructurePart(
+        partNumber: '1',
+        type: 'text',
+        subtype: 'plain',
+        parameters: ['charset' => 'iso-8859-1'],
+        encoding: 'quoted-printable',
+    );
+
+    $mime = MimeMessage::make($part, 'Caf=E9');
+
+    expect($mime)->toBe("Content-Type: text/plain; charset=\"iso-8859-1\"\r\nContent-Transfer-Encoding: quoted-printable\r\n\r\nCaf=E9");
+});
+