1 files changed, 55 insertions, 0 deletions
diff --git a/tests/niminaction/Chapter3/ChatApp/src/protocol.nim b/tests/niminaction/Chapter3/ChatApp/src/protocol.nim
new file mode 100644
index 000000000..4c122d4cc
--- /dev/null
+++ b/tests/niminaction/Chapter3/ChatApp/src/protocol.nim
@@ -0,0 +1,55 @@
+import json
+
+type
+  Message* = object
+    username*: string
+    message*: string
+
+  MessageParsingError* = object of Exception
+
+proc parseMessage*(data: string): Message {.raises: [MessageParsingError, KeyError].} =
+  var dataJson: JsonNode
+  try:
+    dataJson = parseJson(data)
+  except JsonParsingError:
+    raise newException(MessageParsingError, "Invalid JSON: " &
+                       getCurrentExceptionMsg())
+  except:
+    raise newException(MessageParsingError, "Unknown error: " &
+                       getCurrentExceptionMsg())
+
+  if not dataJson.hasKey("username"):
+    raise newException(MessageParsingError, "Username field missing")
+
+  result.username = dataJson["username"].getStr()
+  if result.username.len == 0:
+    raise newException(MessageParsingError, "Username field is empty")
+
+  if not dataJson.hasKey("message"):
+    raise newException(MessageParsingError, "Message field missing")
+  result.message = dataJson["message"].getStr()
+  if result.message.len == 0:
+    raise newException(MessageParsingError, "Message field is empty")
+
+proc createMessage*(username, message: string): string =
+  result = $(%{
+    "username": %username,
+    "message": %message
+  }) & "\c\l"
+
+when true:
+  block:
+    let data = """{"username": "dom", "message": "hello"}"""
+    let parsed = parseMessage(data)
+    doAssert parsed.message == "hello"
+    doAssert parsed.username == "dom"
+
+  # Test failure
+  block:
+    try:
+      let parsed = parseMessage("asdasd")
+    except MessageParsingError:
+      doAssert true
+    except:
+      doAssert false
+