[Enhancement] Add diff lib for kcl test assert errors.

[Peefy]

Enhancement

For example, I want to obtain diff information from the error message in the following code.

import yaml
import difflib

test_merge = lambda {
    original = {
        "metadata": {
            "name": "my-deployment",
            "labels": {
                "app": "my-app",
            },
        },
        "spec": {
            "replicas": 3,
            "template": {
                "spec": {
                    "containers": [
                        {
                            "name": "my-container-1",
                            "image": "my-image-1",
                        },
                        {
                            "name": "my-container-2",
                            "image": "my-image-2",
                        },
                    ],
                },
            },
        },
    }

    patch = {
        "metadata": {
            "labels": {
                "version": "v1",
            },
        },
        "spec": {
            "replicas": 4,
            "template": {
                "spec": {
                    "containers": [
                        {
                            "name": "my-container-1",
                            "image" = "my-new-image-1",
                        },
                        {
                            "name": "my-container-3",
                            "image" = "my-image-3",
                        },
                    ],
                },
            },
        },
    }
    expected = yaml.decode("""\
metadata:
  name: my-deployment
  labels:
    app: my-app
    version: v1
  spec:
    replicas: 4
    template:
      spec:
        containers:
        - name: my-container-1
          image: my-new-image-1
        - name: my-container-2
          image: my-image-2
        - name: my-container-3
          image: my-image-3
""")

    got = merge(original, patch)
    diff = difflib.diff(got, expected)
    assert str(got) == str(expected), "expected ${expected}, got ${got}, the diff is ${diff}"
}

[abhayporwals]

Hey @Peefy, I would like to work on this.
Share some more details that helps, if you can.

[Peefy]

Hey @Peefy, I would like to work on this. Share some more details that helps, if you can.

Hi @professorabhay. Thank you for contributing to the KCL community. The expectation is to provide a diff library written by KCL to display the differences between KCL configurations at the module repo: https://github.com/kcl-lang/modules

[Peefy]

Hello @professorabhay If you have any difficulties, please feel free to communicate at any time. According to that the issue has been open for over two weeks.

[abhayporwals]

Hey @Peefy, I have my exams ongoing but will try to resolve it and raise a PR by the end of Thursday.
Sorry for the inconvenience.

[abhayporwals]

Hey @Peefy, First of all, sorry for the delay. I give it a try but having some hurdles while resolving it.
I couldn't find any diff library written by KCL.
Please provide more context about it.

[Peefy]

Hi @professorabhay, I'm glad you're still working here. The purpose of this issue is to use KCL to develop a difflib library for string diff, just like how Python's difflib does. The things that need to be done are as follows:

• Create a new module called difflib in the kcl-lang/modules repository using kcl v0.7+ and submit the PR to here
• Implementing a simple difflib library using KCL can display the diff of string arrays, just like:

import difflib

print("\n".join(difflib.ndiff("a\na".splitlines(), "a\nb".splitlines())))

The output is

  a
- a
+ b

[abhayporwals]

Ok, Thanks for the update @Peefy.
Take a look at the structure - [KCL v0.7+]

[Peefy]

Ok, Thanks for the update @Peefy.
Take a look at the structure - [KCL v0.7+]

Good Job

[abhayporwals]

What to write in this main.k file or should I raise the PR?

[Peefy]

What to write in this main.k file or should I raise the PR?

You can raise the PR. The next step is to write the implementation of difflib in main.k, and you can refer to the implementation of difflib in Python

[abhayporwals]

Please take a look to that -

class DiffLib {
    companion object {
        fun diff(seq1: CharSequence, seq2: CharSequence): List<String> {
            val result = mutableListOf<String>()

            val dp = Array(seq1.length + 1) { IntArray(seq2.length + 1) }

            for (i in 0..seq1.length) {
                for (j in 0..seq2.length) {
                    when {
                        i == 0 -> dp[i][j] = j
                        j == 0 -> dp[i][j] = i
                        seq1[i - 1] == seq2[j - 1] -> dp[i][j] = dp[i - 1][j - 1]
                        else -> dp[i][j] = 1 + minOf(dp[i - 1][j], dp[i][j - 1], dp[i - 1][j - 1])
                    }
                }
            }

            var i = seq1.length
            var j = seq2.length

            while (i > 0 || j > 0) {
                when {
                    i > 0 && j > 0 && seq1[i - 1] == seq2[j - 1] -> {
                        result.add("  ${seq1[i - 1]}")
                        i--
                        j--
                    }
                    j > 0 && (i == 0 || dp[i][j - 1] <= dp[i - 1][j]) -> {
                        result.add("+ ${seq2[j - 1]}")
                        j--
                    }
                    i > 0 && (j == 0 || dp[i][j - 1] > dp[i - 1][j]) -> {
                        result.add("- ${seq1[i - 1]}")
                        i--
                    }
                }
            }


            return result.reversed()
        }
    }
}

[Peefy]

The logic is right. You can translate it to KCL and raise a PR