### Program Information

Name: comments API--modify a comment
Domain: web service and application
Functionality: This "comments API" manages comments about music: songs, lists, artists and groups. The "modify a comment" service modifies an existing comment and returns a representation of the modified comment as output.
Input: id: An unique identifier for the comment. (Type: String) date: Creation date of the comment. (Type: String) text: The text of the comment. (Type: String) userName: User name of the creator.
Output: id': An unique identifier for the comment. (Type: String) date': Creation date of the comment. (Type: String) text': The text of the comment. (Type: String) userName': User name of the creator.

#### Reference


Metamorphic Testing of RESTful Web APIs
https://dx.doi.org/10.1109/TSE.2017.2764464


### MR Information

#### MR1------modify

Description:
Property:  Modify an existing comment with a specific data, then modify again that comment with different data on all the properties except for id. The values of the properties data, text, and userName of the outputs should be different, and the value of id should be the same. For example, modify the content "Hello World" to "Good Bye", the content of the original comment and the modified comment should be different, while the id remains the same.
Source input: $id_{s}$,$date_{s}$,$text_{s}$,$userName_{s}$
Source output: $id_{s}'$,$date_{s}'$,$text_{s}'$,$userName_{s}'$
Follow-up input: $id_{f}$,$date_{f}$,$text_{f}$,$userName_{f}$
Follow-up output: $id_{f}'$,$date_{f}'$,$text_{f}'$,$userName_{f}'$
Input relation: $id_{s}\equiv id_{f}$, $date_{s}\neq date_{f}$ $text_{s}\neq text_{f}$ $userName_{s}\neq userName_{f}$
Output relation: $id_{s}'\equiv id_{f}'$, $date_{s}'\neq date_{f}'$ $text_{s}'\neq text_{f}'$ $userName_{s}'\neq userName_{f}'$
Pattern: MROP:difference, MRIP:replacement, MRP:asymmetry
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