add test for multipart parser

src/main.zig

@@ -314,3 +314,43 @@ fn fetchFile(response: *http.Response, request: http.Request, filename: []const
         try response.writer().writeAll(&file_write_buffer);
     }
 }
+
+pub const log_level: std.log.Level = .debug;
+test "multipart" {
+    const body =
+        "--1234\r\n" ++
+        "Content-Type: text/plain\r\n" ++
+        "Content-Disposition: form-data; name=file1; filename=ab.txt\r\n" ++
+        "\r\n" ++
+        "Hello!\n" ++
+        "--1234\r\n" ++
+        "Content-Type: application/json\r\n" ++
+        // TODO: add 'content-type' support to content-disposition as well
+        "Content-Disposition: form-data; name=file2; filename=data.json\r\n" ++
+        "\r\n" ++
+        "{\"status\": \"OK\"}\n" ++
+        "--1234--\r\n";
+
+    var buf: [512]u8 = undefined;
+    var multipart = try Multipart.init(
+        body,
+        "multipart/form-data; boundary=1234",
+        &buf,
+    );
+
+    var hzzp_buffer: [1024]u8 = undefined;
+    var part1 = (try multipart.next(&hzzp_buffer, std.testing.allocator)).?;
+    defer part1.deinit();
+
+    std.debug.warn(
+        "\npart={}\n",
+        .{part1},
+    );
+
+    std.testing.expectEqualSlices(u8, "text/plain", part1.content_type);
+    std.testing.expectEqualSlices(u8, "file1", part1.disposition.name);
+    std.testing.expectEqualSlices(u8, "ab.txt", part1.disposition.filename);
+    std.testing.expectEqualSlices(u8, "Hello!", part1.body);
+
+    // var part2 = (try multipart.next(&hzzp_buffer)).?;
+}