reverse-string: Add new exercise by eliaahadi · Pull Request #960 · exercism/problem-specifications

eliaahadi · 2017-10-17T20:53:37Z

new exercise

NobbZ

Also, please remove the .DS_Store files, they do not belong into this repository.

NobbZ · 2017-10-18T05:33:36Z

+
+## Tutorial
+
+This exercise has two files:


This is to specific for a generic exercise description. My Erlang exercises won't have those 2 files, but a lot of other files.

I agree. The tutorial shouldn't really be here, as it is JS specific.

Ok I followed instructions from the specific JS PR 417 here to go over to this general exercise.

Once I'm "approved" of this exercise here, I thought to go back to the JS PR 417 to complete that.

How should I proceed?

@matthewmorgan

NobbZ · 2017-10-18T05:35:11Z

+      "subject": "car",
+      "candidates": ["girl", "Japan", "bear", "candy"],
+      "expected": []
+    },


I don't get this… What is "candidates" for? And how can reversing a three letter long string result in an empty array?

NobbZ · 2017-10-18T05:35:54Z

+      "subject": "ant",
+      "candidates": ["tna"],
+      "expected": ["tan"]
+    },


As well, what is candidates for, and why do you expect an array of strings to be returned?

NobbZ · 2017-10-18T05:36:28Z

+      "property": "reverse-string",
+      "subject": "NinJa",
+      "candidates": ["ajnin"],
+      "expected": ["ajnin"]


Why is the expectation lowercased? I haven't seen this requirement in the DESCRIPTION.md

NobbZ · 2017-10-18T05:39:16Z

Oh, and you need to rename README.md to description.md

ErikSchierboom · 2017-10-18T06:17:04Z

+- Run the test suite and make sure that it succeeds.
+- Submit your solution and check it at the website.
+
+If everything goes well, you will be ready to fetch your first real exercise.


I think this line is copied from the hello-world exercise, and it should be removed I think.

ErikSchierboom · 2017-10-18T06:18:58Z

@@ -0,0 +1,106 @@
+# Reverse String
+
+The introductory exercise to arrays and strings. Just reverse input string.


I would rephrase this to lose the "arrays" bit, as that is a language-specific implementation detail. Maybe just focus on the actual exercise:

Given an input string, return its reversed string.

ErikSchierboom · 2017-10-18T06:19:32Z

+
+## Tutorial
+
+This exercise has two files:


I agree. The tutorial shouldn't really be here, as it is JS specific.

Insti · 2017-10-18T12:24:07Z

@@ -0,0 +1,54 @@
+{
+  "exercise": "revere-string",


Insti · 2017-10-18T12:24:27Z

@@ -0,0 +1,54 @@
+{
+  "exercise": "revere-string",
+  "version": "1.0.1",


first version should be 1.0.0

eliaahadi · 2017-10-18T17:02:43Z

Made more edits. I'm not quite sure how to delete the _DS store files, I don't have it on my folder that I pushed changes. Where do I go about deleting those?

NobbZ · 2017-10-18T17:09:31Z

They are there… Have you done ls -h? Deleting them is possible via git rm ._DS_Store.

Those files are probably not needed in any repository, as they are specific to your computer.

Please create a global gitignore file, as described in https://gist.github.com/subfuzion/db7f57fff2fb6998a16c and add those store files there.

A good start for a global gitignore on a mac is https://www.gitignore.io/api/osx

eliaahadi · 2017-10-18T17:22:59Z

Ok I had a typo when doing git rm, last commit shouldn't have it now.

NobbZ

I've left some comments again.

Some of my former ones remain valid.

NobbZ · 2017-10-18T17:12:52Z

+    {
+      "description": "detects reverse-string",
+      "property": "reverse-string",
+      "input": "robot", "superman", "ramen",


This is not valid JSON.

Also I can't find a word in the desription.md that tells me that I have to handle more than a single string.

And it feels weird that this is the sole testcase…

I'd expect to have at least 3 testcases:

reverse the empty string

reverse a string consisting of a single lowercase letter

reverse a string having more than a single lowercase letter

reverse a string with at least a capital letter

reverse a string that contains a proper sentence with punctuation.

reverse a string twice and check if it is the original again (add a comment that this is perfect for poperty based testing)

NobbZ · 2017-10-18T17:22:37Z

+- Run the test suite and make sure that it succeeds.
+- Submit your solution and check it at the website.
+
+## Tutorial


You can remove everything starting with ## Tutorial up to the end of the file, since it is specific to JavaScript.

The tutorial stuff can be added by each tracks maintainer if they feel the need.

The section about how to run the tests and how to set up the environment (as a student) are generated automatically by each track.

NobbZ · 2017-10-18T17:51:27Z

They are there… Have you done ls -h?

My bad… This has to be ls -a!

And there is still a DS file left in exercises

petertseng · 2017-10-18T18:18:50Z

@@ -0,0 +1,5 @@
+---
+blurb: "Given a string, reverse it’s letters and output a new string."


it's must be its.

eliaahadi · 2017-10-18T21:01:14Z

Added 3 test cases, I'm not sure what the test cases with capitalization and punctuation are suppose to test that's why I didn't add them. I modeled my test cases off the hello world and leap programs since they are some of the beginner programs and they don't have much varied edge cases. Thoughts? Happy to make more edits.

petertseng · 2017-10-18T21:47:27Z

+  "version": "1.0.0",
+  "cases": [
+    {
+      "description": "detects reverse-string",


I disagree with detects. I don't think the function under test is detecting anything. It is reversing a string. The description should reflect that.

petertseng · 2017-10-18T21:48:12Z

+      "description": "detects reverse-string twice and check if it's original string",
+      "property": "reverse-string",
+      "input": "robot",
+      "expected": "robot"


nothing other than the description tells us that reverse is supposed to be applied to this string twice. If it is to be, the property must be different.

petertseng · 2017-10-18T21:48:54Z

+      "description": "detects empty string",
+      "property": "reverse-string",
+      "input": "",
+      "expected": "String is empty, input valid string"


the reverse of "" should be "". This string is only expected if the input is "gnirts dilav tupni ,ytpme si gnirtS"

petertseng · 2017-10-18T21:49:09Z

+      "expected": "tobor"
+    },
+    {
+      "description": "detects empty string",


I disagree with detects. I don't think the function under test is detecting anything. It is reversing a string. The description should reflect that.

same

petertseng · 2017-10-18T21:49:15Z

+      "expected": "String is empty, input valid string"
+    },
+        {
+      "description": "detects reverse-string twice and check if it's original string",


I disagree with detects. I don't think the function under test is detecting anything. It is reversing a string. The description should reflect that.

same

NobbZ · 2017-10-18T21:52:48Z

Tests should be in order, starting with the simplest case. Therefore I think, we should start with the empty string.

Also in the spirit of TDD we should start slowly with a single letter string. Keeping it simple as "a", or "I", both are valid words in the englisch language and therefore plausible test subjects.

So we increase the length to something where we actually see something happen. this is were the student usually starts to implement real logic.

Now some random words to simply check if it was done right.

Last but not least we do some tests with mixed case and punctuation simply to remind the student, that all strings are valid input. I've seen unnecessary verification logic in real world code which rejected valid input just because the examples the programmer had originally hadn't uppercase input (while uppercase was explicitely specified as valid)…

eliaahadi · 2017-10-18T22:21:40Z

Added more edits to test cases. As for reverse-string twice, not sure what a new property should be, so I just put new property called "reverse-string twice". Thoughts or edits? Thanks.

Insti · 2017-10-19T07:32:40Z

+    },
+    {
+      "description": "reverse a string twice and check if it's original string",
+      "property": "reverse-string twice",


What is this trying to test?
What code needs to be changed in a solution that would pass all preceding tests in order for it to pass this one?

This was added on my suggestion, I suggested to add a comment/description as well, that this should be done through property testing like QuickCheck if available.

Can such a test be described using our current json format?
I'm not sure what this is testing that hasn't already been tested.

Maybe you are right. Seems as if I had shoot to fast after heaving heard a podcast about property based tasting lately ;)

I'm not entirely clear what I should be updating now if any, I'm still new to this exercism and open to making changes.

Also, I'm not even sure how reversing a string twice is tested with this json format, is a person suppose to take an input string, call the function, take the output and put it into the input of the next function call? Below is code example.

reversestring("robot"); // -> tobor, reverse string test passed reversestring("tobor"); // -> robot, reverse string twice test passed

I think we can simply put a comment in the “prelude” describing that this is a property that can be tested if such testing tools are available and remove this test completely.

Insti · 2017-10-19T15:50:33Z

+      "expected": "tobor"
+    },
+    {
+      "description": "reverse a string consisting of a single lowercase letter",


Description does not match test.

I'm not sure what you mean, the "reverse a string" case with robot string or "reverse a string with a single lowercase letter" with string WOLf?

a “string consisting of a single lowercase letter” has a length of 1, your string has a length of 4.

Oh I see, I read the test as any string length as long as string has 1 single lowercase letter, not a string that ONLY has a single lowercase letter. If the only single letter case is more clear, then I can just update that.

I don't think character case is something that needs to be tested in this exercise. Seems a superfluous detail.

As I've explained in another comment, I've seen a lot of code that has arbitrary “validation” built in, because there were no examples with uppercase values…

Therefore I think, we should explicitely show, that any kind of input is to be expected.

I think it's OK to have some mixed case examples. I also think that this test suite spends too much time concentrating on case based tests.

A capitalised palindrome might be an interesting test.

Insti · 2017-10-19T15:51:44Z

+      "expected": "fLOW"
+    },
+    {
+      "description": "reverse a string having more than a single lowercase letter",


This also describes the third test?

I'm not quite sure what you are asking. Descriptions should align to cases.

When you are implementing a solution to this problem, you should be able to read the description and know from that what new aspect of the problem the test covers.
"a string having more than a single lowercase letter" has already been tested in the third test: "robot"

So either this test is redundant and should be removed because it is testing something that has already been tested.
OR
This test needs a description that describes why it needs to test this particular input.
Why is "DEssERTS" useful to test?

Perhaps you have a good example in one of the exercises that clearly shows good JSON and description files. I want to make sure we are on same page and not talking in circles for this simple problem. I know I'm new to this, so this will take alittle longer the first time around.

Insti · 2017-10-19T15:52:27Z

+      "expected": "nemaR"
+    },
+    {
+      "description": "reverse a string that contains a proper sentence with punctuation.",


This is also the first test that contains a space.

Insti · 2017-10-20T09:56:35Z

+      "expected": ""
+    },
+       {
+      "description": "reverse a single character string",


"reverse a" is redundant and can be omitted from the descriptions.

eliaahadi · 2017-10-20T18:03:37Z

Made more JSON and description file edits, happy to do more. If anybody has JSON and description files as examples so I can see what is good to commit, please let me know.

ErikSchierboom · 2017-11-07T07:44:03Z

+      "expected": "tobor"
+    },
+    {
+      "description": "reverse a string with at least a capital letter",


Maybe shorten this to: "reverse a string with a capital letter"

ErikSchierboom · 2017-11-07T18:59:37Z

@@ -0,0 +1,5 @@
+Reverse a string
+
+For Example:


Could you change "For Example" to "For example"?

ErikSchierboom · 2017-11-07T19:00:15Z

+      "expected": "nemaR"
+    },
+    {
+      "description": "reverse a string that contains a proper sentence with punctuation",


Maybe shorten this to "reverse a string with punctuation"

eliaahadi · 2017-11-07T19:34:17Z

@ErikSchierboom ok in last 2 commits, I think those changes were implemented correctly.

Insti · 2017-11-07T19:56:06Z

@eliaahadi I wasn't approving earlier because I agreed with the issues that @petertseng had raised.

petertseng · 2017-11-07T20:03:11Z

@@ -1 +0,0 @@
-node_modules


this line already existed. it should not be removed.

Insti · 2017-11-07T19:59:08Z

@@ -1 +0,0 @@
-node_modules


There is still a .gitignore change here.
Are you checking the files that have changed?

Try running: git diff --name-only master on your local branch.

@Insti I don't think I added .gitignore to
case description updates commit, please let me know if I did.

git log master.. -- .gitignore

Commits: 57f7581 and fcdb93b both modified the .gitignore file.

In fcdb93b you deleted a line you did not add in 57f7581

Insti · 2017-11-07T19:59:52Z

+      "expected": ""
+    },
+    {
+      "description": "reverse a string",


remove "reverse"
what about "a word"

Why are you testing this string?
Is the fact it has symmetric os relevant?

I like this suggestion.

Insti · 2017-11-07T20:00:15Z

+      "expected": "tobor"
+    },
+    {
+      "description": "reverse a string with a capital letter",


remove "reverse a"

what about "a capitalized word"

I like this suggestion.

Insti · 2017-11-07T20:00:27Z

+      "expected": "nemaR"
+    },
+    {
+      "description": "reverse a string with punctuation",


remove "reverse a"

what about "a sentence with punctuation"

I like this suggestion.

Insti · 2017-11-07T20:00:57Z

+      "expected": "!yrgnuh m'I"
+    },
+    {
+      "description": "reverse a string and check if it is the same as input string (Palindrome)",


What about just "a palindrome"

I like this suggestion.

Insti · 2017-11-07T20:05:32Z

@@ -0,0 +1,5 @@
+Reverse a string


Short description is good 👍

Agree, short and to the point!

NobbZ · 2017-11-07T22:16:00Z

the file exercises/.DS_Store should not be in this PR, since it does not contain anything related to problem specifications

The addition of .DS_Store to .gitignore should not be in this PR, since this PR is about adding reverse-string, not about adding new items to gitignore.

exactly. This was already pointed out by me a month ago:

Please create a global gitignore file, as described in gist.github.com/subfuzion/db7f57fff2fb6998a16c and add those store files there.

A good start for a global gitignore on a mac is gitignore.io/api/osx

In a repositories .gitignore do only belong files that might get generated by the repositories build workflow.

Files specific to a certain IDE, an editor or an operating system belong to a global git ignore as described in the linked and quoted comment.

eliaahadi · 2017-11-08T18:53:31Z

Ok in last git push, I just edited and pushed the canonical-data.json file. I don't think I added .gitignore or the DS_store files. I even did a rm in command line to those files and looked to see if there were hidden. If they are still added, I'm missing something then to do to remove them.

coriolinus · 2017-11-08T19:13:47Z

@eliaahadi The issue you're facing is that you've already committed an incorrect .gitignore; even though you're not re-adding it to new pushes, the changes are still in the changeset implied by this PR.

You need something like this:

# add this first line only if you do not already have the exercism master 
# configured as a remote named exercism
git remote add exercism git@github.com:exercism/problem-specifications.git 
# once that's configured, you can 
git checkout exercism/master -- .gitignore
git add .gitignore && git commit -m "Restore .gitignore"
git push

[edit]
Just saw that you're on your own master branch, so you need to pull from exercism/master instead of your own master branch. Updated the instructions.

eliaahadi · 2017-11-08T19:17:07Z

@coriolinus thanks, I did just try that now from your instructions. It says fatal: pathspec '.gitignore' did not match any files when doing either the git checkout or git add shown below.

Elias-MBP:exercises eliaahadi$ git checkout master -- .gitignore
error: pathspec '.gitignore' did not match any file(s) known to git.
Elias-MBP:exercises eliaahadi$ git add .gitignore && git commit -m "Restore .gitignore"
fatal: pathspec '.gitignore' did not match any files

Thoughts?

coriolinus · 2017-11-08T19:22:24Z

@eliaahadi See my edit to my previous response.

reverse-string

eliaahadi · 2017-11-08T20:14:52Z

@coriolinus ok I did that and also thought I was on the exercism/master by typing git pull https://github.com/exercism/problem-specifications.git shown below.

Elias-MBP:problem-specifications eliaahadi$ git pull https://github.com/exercism/problem-specifications.git
remote: Counting objects: 286, done.
remote: Compressing objects: 100% (140/140), done.
remote: Total 286 (delta 168), reused 243 (delta 146), pack-reused 0
Receiving objects: 100% (286/286), 54.27 KiB | 624.00 KiB/s, done.
Resolving deltas: 100% (168/168), completed with 21 local objects.
From https://github.com/exercism/problem-specifications
 * branch            HEAD       -> FETCH_HEAD
error: There was a problem with the editor 'vi'.
Not committing merge; use 'git commit' to complete the merge.
Elias-MBP:problem-specifications eliaahadi$ git checkout exercism/master -- .gitignore
fatal: invalid reference: exercism/master
Elias-MBP:problem-specifications eliaahadi$ git add .gitignore && git commit -m "Restore .gitignore"
fatal: pathspec '.gitignore' did not match any files

I still get the error. I guess I'm still not on the exercism/master. Is git pull not the right way to get to exercism/master?

Insti · 2017-11-08T22:18:52Z

    },
    {
-      "description": "reverse a string and check if it is the same as input string (Palindrome)",
+      "description": "a string that reads the same backward as forward (i.e. palindrome)",


Why are you defining palindrome here?

I don't think everybody knows what a palindrome is, and personally, I'd rather have it defined here than have to google it. If you feel strongly we don't need to define it, please state why you think everybody knows this. Perhaps wording can change some.

coriolinus · 2017-11-08T22:39:57Z

@eliaahadi git pull is the way to update your entire working tree from a remote site. git remote, which I recommended for you, saves a remote site with a short name so things like the git checkout command I gave you can work.

However, I just realized we were going through all this over a file with one line in it. Using git is killing a mosquito with a sledgehammer. Do this:

echo "node_modules" > .gitignore
git add .gitignore && git commit -m "Restore .gitignore"
git push

It may be possible for things to go wrong if you do those commands in that order, but off the top of my head I can't think of how.

ErikSchierboom · 2017-11-09T07:35:33Z

To reset the .gitignore file, you should also be able to do:

git fetch exercism
git checkout exercism/master .gitignore

That should reset the .gitignore file to the version in the master branch of the exercism repository (granted you use exercism as the remote name).

eliaahadi · 2017-11-09T16:22:31Z

@coriolinus I pushed the gitignore using those commands. Hopefully, it was done right. If there are any more edits in general, if not please let me know.

coriolinus · 2017-11-09T16:30:38Z

@eliaahadi Very good, it worked! I believe that this solves the most pressing issue with this PR.

Now it's a matter of the rest of the reviewers deciding whether or not all of their issues are now resolved.

ErikSchierboom

Looking good to me!

it is no longer the case that gitignore got changed, and that was my objection, therefore my objection is dismissed.

rpottsoh

@eliaahadi thanks for your hard work and perseverance.

Insti · 2017-11-09T18:59:20Z

+      "expected": "!yrgnuh m'I"
+    },
+    {
+      "description": "a string that reads the same backward as forward (i.e. palindrome)",


Continuing discussion from: #960 (comment)

It is helpful for descriptions to be short and to the point, so either

"a string that reads the same backwards and forwards"
or
"a palindrome"

but not both.

My preference is for "a palindrome", because that is the briefest description of what it is.
It's still possible to solve the problem without knowing the definition of the word and the definition can easily be found by a search if necessary.

To give a concrete example of why concision is useful, consider the output of programs which generate tests based on the canonical data. Which is best:

fn test_a_palindrome() { ... }

fn test_a_string_that_reads_the_same_backwards_and_forwards() { ... }

fn test_a_string_that_reads_the_same_backward_as_forward_ie_palindrome() { ... }

Depending on which option gets merged, the Rust test generator will create one of the above. IMO, the shortest is the best.

Ok I'm convinced. I added just "a palindrome" for description to latest commit.

Please review @Insti. Thanks.

Insti

I think we've finally got there.
Remember to squash and merge.

ErikSchierboom · 2017-11-11T08:32:10Z

Merged! Thanks for the hard work @eliaahadi!

eliaahadi · 2017-11-11T15:51:02Z

Great thanks to all! I learned and glad I could help out.

reverse string

8f3e2b2

eliaahadi mentioned this pull request Oct 17, 2017

reverse string exercise exercism/DEPRECATED.javascript#417

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Insti changed the title ~~reverse string~~ reverse-string: Add new exercise Oct 18, 2017

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updates per exercism#960

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delete DS store

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updated test cases mostly

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added edits to test cases

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updates JSON and description files

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eliaahadi added 2 commits November 7, 2017 11:29

description & can data edits

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no gitignore or .DS_store

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Comment thread .gitignore

@@ -1 +0,0 @@

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this line already existed. it should not be removed.

Insti suggested changes Nov 7, 2017

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case description updates

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Merge https://github.com/exercism/problem-specifications

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reverse-string

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Restore .gitignore

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edit to palindrome description

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Insti approved these changes Nov 11, 2017

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ErikSchierboom merged commit 6c2f275 into exercism:master Nov 11, 2017

		@@ -0,0 +1,106 @@
		# Reverse String

		The introductory exercise to arrays and strings. Just reverse input string.

		@@ -0,0 +1,5 @@
		---
		blurb: "Given a string, reverse it’s letters and output a new string."

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eliaahadi commented Oct 18, 2017 •

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eliaahadi Oct 19, 2017 •

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