Forem: blackode

Elixir as Wife

blackode — Sat, 03 Aug 2019 20:29:57 +0000

Well, ladies & gentlemen presenting you Elixir, the adorable WIFE.

Do you love your wife? Of course you can’t answer me in face as you can’t see me while reading this. Just look at your heart and just think. If you are thinking then you are not loving. F**k man don’t think, It’s not a question about the science or astrology to think and answer. I know it is still hard for you to say “YES” . It’s a joke you can laugh freely as I can’t charge you for this.

Any way, who else loves the wife in life uses knife to cut you in half. Man this is an insane rhythm of saying as wife, life and knife. Do you know why they sound alike ? It’s cos they follow similar protocol of being good and bad transformations with out any emotion.

My wife, ELIXIR I call her with another name for now I forgot to tell you. It’s almost 3 years passed after our marriage. I’d like to share how does it feel when you marry a girl who possessed completely by ELIXIR.

It’s a fictional. Again I am saying it’s a fictional story. If anyone either directly or indirectly related to this, man you are lucky take this as granted.

Supervisor

One fine morning, it’d been raining whole night. The weather was so romantic. The cool breezes are very tempting. So I asked her, “Let’s have children”. She said, “ The Supervisor is not starting our children processes”. What? Ok. Then I asked, “Why?”. She replied turning towards me spreading her hands wide in anger, “ It’s cos of f**king run time errors in our relationship”. Then after, I took a step back from her, turned back and escaped silently, unnoticed.

To silent her anger, I told her that I am going to buy her new jewellery and matching dress. At any cost, I’m not going to do it. It’s a big lie and life savior for any husband.

Gen-Server

After solving our run time problems in our running relationship, we went out on a vacation to a place where you find all the people beautiful except your wife and husband as you already saw them half naked, the Beach. It’s sandy and hot outside.

While we are walking along the beach, holding her hand, she asked me why I always send late reply to her message. I said, “I was busy in taking other calls”. Then, she advised me to assign multiple workers to handle info from external messages. So, now I can handle calls from home(Wife Module) by casting her synchronously and asynchronously.

On the way to my home from office, I met with an incident. A stranger came to me and asked me to deliver a message to my wife that he is going to die(exit process), and not to re spawn him again. I didn’t understand what he is talking about, called my wife and explained about the incident. Then she said, “ I made myself distributed. So, external processes are trying to link with me.” I said, “What the hell ?”. I cannot do more that. She exposed her process identifier, PID and tried to explain me about the general concurrent process to conquer me.

Behavior

I took almost 2 weeks to come out from the shock she gave with her distributed nature. From then I kept a gate keeper to not let anyone with out a secret cookie. When everything is fine she told me that her friend is coming home. I let her to invite.

To impress her friend, I put on new dress and added scent to appear myself special. Men will be Men. Me and my wife were waiting at the gate to welcome her friend. I’m more excited. A car came and stopped right in front us. I am adjusting my Tie and coat to give grant welcome.

The waiting friend had finally revealed and to my surprise he is a MAN who is better than me in all possible angles. I can’t digest it. I except a young and beautiful girl at least a pretty good looking lady. Now, I am in a sarcastic mood. Anyway, who wishes a man like macho who is better than him as her wife’s friend. That’s a tragedy. Right now he is with my wife. They were laughing and I am crying inside.

He is almost behaving like her own husband. A volcano is running in my heart. No more controlling. So I asked about his weird behavior then my wife told me that he is using husband module and overriding all my defined functions. use Husband , A behavioral module. I said, “What heck is all that ?”. She told, “It’s not a heck. It’s your behavior and rights were shared ” F**k man every time she comes with a new concept. From then instead of understanding her I started following her.

We eventually ended up each other being at different NODEs with different cookies.

Thanks for reading.

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Happy Coding :)

Creating co-authored commits--command line--git

blackode — Fri, 07 Dec 2018 08:41:33 +0000

Photo by NeONBRAND on Unsplash

Give Credits ⭐️ whoever deserves

Brief Story

Suppose, you are working on a project which uses the git tool for version management and it is a team project where you see multiple authors contributing the code.

You are assigned with a task and you took the help from one of the co-programmers to get it coded.

If you are really concerned about the help and want to credit the co-programmer then you can do that by making co-author-commit.

Giving credits to the programmer is sure of another help from him — blackode

Things to know Before adding a co-author to a commit

Co-author Email
Co-author’s commit to count as a contribution-use email associated with their Github account
If co-author’s email is private, use their GitHub-provided no-reply email to protect their privacy.

TIP

Helping Co-author to find their no-reply email and get shared

settings > emails

Co-authored-by commits

Here no things are unknown to you. But, we are doing things differently.

Just like you do for a regular commit message and after adding the meaningful description you need to add two empty new lines instead of adding a closing quotation " .

git commit -m "New style of coding
>
>

On the next line of the commit message, type
Co-authored-by: author-name <name@xxx.com> with specific information for each co-author. After the co-author information, add a closing quotation mark.

Adding multiple co-authors

Give each co-author their own line and Co-authored-by: commit trailer before closing quotation mark.

After adding your beautiful commit message, in the next push, the message appears with co-authors

The Live Execution

Hope you like them. Thanks for reading…

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https://t.me/blackoders

Happy Coding !

The Secret behind Elixir Operator Re-Definitions: + to -

blackode — Sun, 05 Aug 2018 23:59:02 +0000

Photo by rawpixel.com on Unsplash

Hello, everyone. Today, we are going to do some crazy stuff. This article is just for fun. The only intention is to show you this can possible in elixir.

The universal meaning of + is to add but for a change, we are making this as subtraction.

How to achieve this ?

We can use def constructs (def, defp, defmacro, …) for re-defining the operators in elixir.

The Only 1 Rule

The only rule is a name of definition. It should be same as how we use the operator while coding. In general, we use + as a + b So, our definition name should be same as a + b .

Let’s do things in Wrong

All your operator re-definitions **should reside inside the **module because as we all know the fact that definitions cannot stand outside the module.

Check the following code for re-defining + to -

defmodule MyWrongOperators do

  def a + b do
    a - b
  end

end

Nothing is new here. We have just created a function or definition but with a little tricky name.

Boom!! You have turned the world upside down. We are just doing the things as they are possible and elixir allowed us to do. But these are nothing to do in the real world. Just for fun.

How to use?

Here, in elixir, there exists a power that pulls you back from using even though it is allowed you to create with out any hurdles.

If you force to use the module like in regular style of coding, it hits you with an exception. Lets check that.

iex> import MyWrongOperators

iex> 1 + 2

** ** (CompileError) iex:4: function +/2 imported from both MyWrongOperators and Kernel, call is ambiguous

Compile Error When Using the Module Directly

Well, what is the power throwing you this error by not allowing? Can you think for a while and take a guess?

I don’t want to linger you anymore. The Kernel module loaded by default. This Kernel module contains a +/2 function which is also loaded. So, when we are importing our module MyWrongOperators , we loaded +/2 function again. Now with in our scope, there exist two +/2 definitions. So, the compiler got confused here.

How to bypass this ?

Well, we need all the functions in Kernel module except the +/2. This can be achieved with except while loading a module.

import Kernel, except: [+: 2]
import MyWrongOperators

The above LOC clearly tells not to load the +/2 function. So, we only have one +/2 definition from the module MyWrongOperators . So, the compiler can now use +/2 definition with out getting confused.

iex > import Kernel, except: [+: 2]
 Kernel

iex> import MyWrongOperators
 MyWrongOperators

iex> 1 + 2
-1            # 1 - 2 operation performed here as we defined.

The perfect Usage

In the above screen shot, at iex(3) line we are loading the Kernel module with out letting it to load +/2 definition. So, it worked perfectly.

We successfully executed the wrong operations.

Things to Remember

Q. Can I create new operator ?
Ans. No. But, Elixir is capable of parsing a predefined set of operators like

Q. Can I Override every other operators ?
Ans. Yes. You can. But, while using don’t forget to import Kernel module with those override operators as exceptional.

Q. Is it good to override operators ?
Ans. Of course it not good and not recommended.

Q. Why it is not recommended ?
Ans. Custom-defined operators can be really hard to read and even more to understand, as they don’t have a descriptive name like functions do.

Live Demo

https://asciinema.org/a/151933

Warning
Highly not recommended to do…

Happy Long Coding Life :)

The Rigid Code Behind Smooth Code— Elixir Intermediate

blackode — Fri, 03 Aug 2018 12:57:28 +0000

What you see is more simplified.

Photo by Jamie Street on Unsplash

This article shows you the rigid lines of code behind smooth lines you write in elixir.

As we know, the most of the Elixir programming language is written in Elixir itself with the power of Macros and also we all know why we love to code in Elixir because of its simplicity. But, today we are going to walk back to find the light in the dark.

I just want you to observe the following line of code for a while

if 1+2==3, do: :this, else: :that

Here, I am not gonna ask you what this results to. But, I am asking you how this gonna transform eventually.

Let’s observe the transformations.

As we know the elixir allows the function call with out () . This is why the function calling is simple. But, I recommend to use () which is more understandable about what is going on.

If you observe above line, we have couple of , .

This is more likely if is taking three parameters 1+2==3 , do: :this and else: :that but, in real it is taking two.

The last two parameters do: :this and else: :that are together called a KeyWord List .

If you don’t know what a keyWord List is, It is likely a list where its list elements should be tuples of two elements where first element should be an atom .

In one sentence, keyword list is a list of tuples where tuple size should be two (2) and first element in a tuple is an atom . In real it is list of key-value **pairs where **key is an atom and value can be any .

Consider the following example

iex> list = [{:a, 1}, {:b, 2}]

[a: 1, b: 2]

iex> list == [a: 1, b: 2]

true

Here [{:a, 1}, {:b, 2}] == [a: 1, b: 2] . Enough with keyword lists .

Let’s jump back to our line of code

if 1+2==3, do: :this, else: :that

If the last parameter to pass is a KeyWord List , we no need to wrap elements inside the [] square brackets likely we do in general.

hello("medium", user_name: "blackode", lang: "elixir")

is same as

hello("medium", [user_name: "blackode", lang: "elixir"])

Here, both are considered as valid.

So, the line of code is transformed from

if 1+2==3, [do: :this, else: :that]

if( 1+2==3, [do: :this, else: :that] )

Now, observe the first parameter 1+2 == 3 which is (1+2)==3.

Here, before resolving == we have to add (1+2) .

The (1+2) is more likely a function with two parameters. It is an infix notation and + is called an infix operator.

It is a different way of doing certain functions where the function_name is in the middle. The left **and **right **values are passed as **first **and **second parameters respectively to the function.

So, the traditional syntax of representing (1+2) is +(1,2) .

Similarly we break down the another infix operator == as ==(+(1,2), 3) just like we did for + nothing more fancy here.

Well, so far we have break down the +(1,2)==3 to ==(+(1,2), 3) .

Here, we cannot use the infix operators with out its module name where they are defined. All the operators are defined inside the module called Kernel . This is the default module in elixir.

So, again we break down ==(+(1,2), 3) to Kernel.==(Kernel.+(1,2), 3)

Now, the line is transformed to as following

if(Kernel.==(Kernel.+(1,2), 3), [do: :this, else: :that])

We all know that if is a macro which is more likely represented Kernel.if

So, putting all together and breaking down the infix functions, the line again is transformed into

Kernel.if( Kernel.==(Kernel.+(1,2), 3), [do: :this, else: :that ] )

live execution in iex

The best part is, the elixir compiler will take care of all these transformations.

We no need to write all the stuff like above.

Hope you got some idea about hotness behind the cool syntax. For deeper understanding, read more about the MACROS.

Happy Long Coding Life :)

1010 Killer elm Tips to code like a master

blackode — Wed, 01 Aug 2018 12:59:54 +0000

Pro elm tips to write code like a pro

designed using https://crello.com

The using elm in production involves teaching and learning. This article comprises of 10 killer pro elm tips that you may or may not know.

0001 — type alias as a function

The type aliases can be used as functions to construct a new value.

> type alias User = { name: String, age: Int }
> user = User "john" 23
{ name = "john", age = 23 } : Repl.User
> user
{ name = "john", age = 23 } : Repl.User

You have to just pass the initial values in the order of the type alias definition.

0010 — calling infix functions

In elm, almost everything is a function or can act like a function.

The addition operation in elm is just a function call using +. The definition of the + is like

(+) : number -> number -> number

The type specs clearly tell you that it takes two number parameters and returns a number. The way of calling this function is different because it is Infix function.

Infix functions are the functions whose name is in between the parameters. The left side parameter is passed as the first parameter and the right parameter is passed as the second parameter.

example: 1+2

In the above example, + is the function name and 1,2 are its parameters where 1 is the first parameter and 2 is the second parameter.

You can also call the infix function by wrapping function name inside the parenthesis () like (+).

> (+) 1 2
3 : number

-- which is the same as calling 
> 1 + 2
3: number

0011 — function composition

As you know elm is everywhere functions. You can combine functions to form another function using >>

> wordCount = String.words >> List.length
<function> : String -> Int

> wordCount " Medium is full of knowledge resources"
6 : Int

The wordCount function takes String as input and returns Int. The passed String values passed to String.words which in return gives the List String is again passed to List.length which gives Int value.

This is pretty useful.

type distribution

0100 — point free

This point-free style coding is where you omit one or more arguments in the body of the function.

To understand this concept, look at the following examples.

Here I am trying to write a function named double which doubles the given value.

> double num = num * 2
<function> : number -> number

> double 5
10 : number

Here, you can omit the argument num

You can do magic like

> double = (*) 2
<function> : number -> number

> double 5
10 : number

> plus = (+)
<function> : number -> number -> number

> plus 5 5
10 : number

0101 — special function for tuple creation

In elm , you can use the (,). This is a special function used to create tuples. The magic is, it allows you to use as many , inside the ().

E.g (,,) constructs a 3-tuple and (,,,) a 4-tuple.

Check the following examples to understand this more

> (,) "apple" "banana"
("apple","banana") : ( String, String )

> (,,) "apple" 12 "banana"
("apple",12,"banana") : ( String, number, String )

> (,,,) 1 2 3 4
(1,2,3,4) : ( number, number1, number2, number3 )

For N , you have to give N+1 args

You can use as many commas as you want. The , will act as an infix function where the function name is between the two args.

0110 — Special notation in the function definition to pattern match

Consider you have a record model with following content

> model = {name = { firstName = "john", lastName = "ankanna"}, age = 23}

{ name = { firstName = "john", lastName = "ankanna" }, age = 23 }
    : { age : number, name : { firstName : String, lastName : String } }

If you observe the model, it has nested record name with firstName, lastName .

Suppose, you need to update the firstName field inside the model then you can do pattern match over parameters like following.

> updateFirstName ({name} as model)= {model | name = {name | firstName = "joe"}}

<function>
    : { c | name : { b | firstName : a } }
      -> { c | name : { b | firstName : String } }

The {name} as model is a pattern matched here.

pattern match

Now, you simple pass the defined model to the function updateFirstName to update firstName field inside name .

>updateFirstName model
{ name = { firstName = "joe", lastName = "ankanna" }, age = 23 }
    : { age : number, name : { lastName : String, firstName : String } }

updated firstName

0111 — unit type ()

A unit type is a type that allows only one value and thus can hold no information. Sometimes it is also referred to as the type of 0-tuples.

It is denoted by () and its value is same () .

> void = ()
() : ()  -- value : type are same here

Read unit type

1000 — <| operator

This <| has lower precedence than function expression.

The f(g(h(x))) can be written as f <| g <| h x

Check the following example

> add10 = (+) 10
<function> : number -> number

> mul10 = (*) 10
<function> : number -> number

> 10 |> mul10 |> add10
110 : number

> mul10 <| add10 <| 10
200 : number

Let us do some crazy stuff

>add = (+)
<function> : number -> number -> number

> 10 |> (add <| 10)
20 : number

> (10 |> add) <| 10
20 : number

> 10 |> add <| 10
-- SYNTAX PROBLEM -------------------------------------------- repl-temp-000.elm

Conflicting associativity for binary operators (|>, <|). Consider adding
parentheses to disambiguate.

1001 — pattern match a list with at least elements

If you want to match a list with at least two items inside the list you can take the advantage of :: .

a :: b :: rest

Implementation

For an example, you have to return [] if the list has items less than 2 or else you have to return the rest of the list.

input: [1,2,3,4,5] output: [3,4,5]
input: [1] output:[]

import Html exposing (text)

rest list = 
  case list of
    a :: b :: rest -> --this matches list with at least two items
      rest
    _ -> 
      []

main =
  text <| toString <| rest [1,2,3,4,5] -- returns [3,4,5]

import Html exposing (text)

rest list = 
  case list of
    a :: b :: rest -> --this matches list with at least two items
      rest
    _ -> 
      []

main =
  text <| toString <| rest [1] -- returns []

1010 — Similar => function in elm

> add1 = \n -> n +1
<function> : number -> number

> add1 5
6 : number

Hope you have enjoyed the whole context.
Feel free to share and let others get benefited from you.

Happy Long Coding life :)

Killer Elixir Tips Github

blackode — Mon, 30 Jul 2018 15:07:48 +0000

Killer Elixir-Tips

Elixir Tips and Tricks from the Experience of Development. Each part consists of 10 Unique Tips and Tricks with clear explanation with live examples and outputs. These tips will speed up your development and save your time in typing code as well.

You can read specific parts with following links...

GITHUB KILLER ELIXIR TIPS & TRICKS

Share if they are worth.

Happy Long Coding life :)

A Beautiful Love between Elixir & Programmer — love-letter.

blackode — Mon, 30 Jul 2018 08:32:46 +0000

To love with elixir feelings.

Photo by Ryan Holloway on Unsplash

Dear sweetest Elixir — writing with ❤️,

I saw you very first time in a conference with your farther (creator) **José Valim. Seeing you directly into your purple eyes, my heart felt like a **mountain of snow, started melting bit by bit and eventually turned melting byte by byte. I tried to control it from melting down, I didn’t and I discerned, I have been spawn_link with you.

Your meeting is the best day of my life.

Photo by Everton Vila on Unsplash

The moment I saw the shape of you syntax, I didn’t take off my eyes from you. I stared at you not failing a second with a shower of love and shine. My pal, sitting next to me, interrupted me from looking into your eyes. I just turned to him and restarted looking at you simple one for one.

I feel like kissing 😽 by with my hand around your waist. I feel like walking in a shower of love holding your hand, staying together and looking into your eyes without a blink. I feel your presence in me whenever I feel to code.

Photo by Annie Spratt on Unsplash

With your enormous love ❤️, turned me into an immutable living creature, bringing the fame and name as a person of programming with your outstanding list of features and awesome functionalities. I defined a structure to my style of coding mapping with your pattern of love.

You look fresh and pure on every day. You will surprise me every time you come up with a new update. I adopt you as a child. You are the greatest monument ever built in the history of coding.

You are simple, smart and sweet ❤.

Photo by Amy Treasure on Unsplash

You have been my best moment from the moment I saw 😍 and looked into your lovable purple eyes. You are so kind with your GenSever heart of helping in parallel. I started thinking out of the box after our first meet.

I started following your footsteps like a shadow in the light. You are my candle in the darkness of errors. Unknowingly, you happen to be my beautiful mentor and letting me dwell into your lovable heart ❤️. Since then, you have been my map to travel deep inside the universe and have been the node in my life to start the fresh coding life again.

You came and changed everything in me, on me, and of me. Now, being apart from you, can’t even give a thought to.

You happen to be my first thought when we are far from each other.

Photo by Lotte Meijer on Unsplash

I feel the presence of freedom, joy, and happiness when I keep coding with you. I love the way you let me turn you into the shape I like meta-programming . I never ever thought I’d love ❤️ you this much in coding and I never planned to be with you this often.

Looking into the night sky with thousands of stars ⭐️ ⭐️ ️ ⭐️ ⭐️️, I remember your million processes, because they sparkle in performance exactly like stars ⭐️ ⭐️ ⭐️. When I see the sun ☀️ I remember you because you brighten not just my day, but my entire coding life.

I like to travel with you in a lifeboat in deep in the middle in the ocean in alone forgetting the world.

Photo by Théo Roland on Unsplash

Sometimes, observing your beauty in coding syntax makes me absolutely speechless. Words fail me. I love you so much that I’m going crazy with you. I can’t stop thinking and dreaming about you. Only it makes me feel coding alive. Coding would be such a dark place without your presence.

The only real thing in this world is time, you saved a lot of mine with your short and smart way of coding style — pattern matching.

Coding with you is an unexplained feeling. It’s eternal and enormous that doesn’t fit in any words, especially these three simple words** “I love you”**.

— Yours lovingly

❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤

An Elixir Programmer —

My feeling 😃 after writing this —

Coding in Elixir is much easier than writing a love letter to propose Elixir.

Long live Elixir. Dedicated to all programmers in love ❤️ with Elixir and to the Creator **José Valim** for an outstanding language.

Share your feelings as an Elixir Developer.

Happy Elixir Coding :) Keep always smiling 😃 😃

2 Biggest ExUnit Improvements in Elixir 1.7

blackode — Sun, 29 Jul 2018 11:22:06 +0000

Arguments in the failure report
Running mix test with the failed flag

1. Arguments in the failure report

We mostly do assertions like

assert is_valid_card(card_type, card_number)

without using any comparison operators like < > <= == >= inside the unit test cases. Everybody likes being smart. Of course, I do too.

Personal Experience or impression to write this article:

I have had an experience on the peculiar behavior of maps with two types of keys allowed to write a map in elixir.

I used a map with binary keys and trying to test them over a map with keys of type atom. Every time I do, the test gets failed. Though I am sending a correct map, being the keys are of a different type, it gets failed.

It took me a whole day to figure it out. 🌞

I am always trying to debug the code logic instead of arguments that are passed. If the error report has this feature before, I could have saved a day in my life.

Luckily we are having in the latest release.

The Elixir 1.7 versions are smart enough to tell about the arguments given to the function, here is_valid_card(card_type, card_number).

As a programmer, I don’t like the documented proof. I always prefer the test_cases. Well, let’s test this feature.

Before continuing further, I would like you to know the versions I am using at the moment of writing article.

**Elixir* and Erlang OTP versions*

To test this feature, we will create a project basic_math and a simple function is_valid_card/2 which is completely an idiot one. This is used to check whether the given card_number of card_type is valid or not.

We aren’t much worried to implement the complete logic here. The function, is_valid_card/2 does nothing useful just, it will just judge the length of the card_number based on the card_type.

 $ mix new basic_math && cd basic_math

The above shell command creates a new Elixir project and changes your current working directory to the basic_math.

Hope, you all knew the project structure. Well in case if you don’t, check out to My First Project in Elixir.

Open the file lib/basic_math.ex and put the following lines of code.


#lib/basic_math.ex

defmodule BasicMath do

  def is_valid_card(card_type, card_number) do
    case card_type do
      :debit ->
        card_number
        |> Integer.to_charlist()
        |> length
        |> Kernel.==(12)

       :credit ->
        card_number
        |> Integer.to_charlist()
        |> length
        |> Kernel.==(10)

       _ ->
        {:error, :invalid_card_type}
    end
  end
end

After adding the code, the file looks like in the following screenshot…

Quick Docs about the code in basic_math.ex file.

The definition is_valid_card/2 receives two parameters card_type and card_number . We are case matching on card_type. It matches for two case values :credit & :debit and I hope you have understood the rest of the code. It is nothing harder than lifting a 1 gram of stone. Nothing like that, I am just kidding.

Unit Test Cases

Now, we will write some unit test cases to test our code.

Before using, test the code.

Open the file test/basic_math_test.exs and add the following lines of code

Basic Setup

Add the following code

defmodule BasicMathTest do
  use ExUnit.Case
  import BasicMath
  doctest BasicMath

end

Test Cases for debit card

describe "debit_card" do

     setup do
    {:ok, type: :debit, valid_card: 123456789012, invalid_card: 1234567890} 
     end

     test "valid debit card", %{type: type, valid_card: valid_card} do
      assert is_valid_card(type, valid_card)
     end

    test "in-valid debit card", %{type: type, invalid_card: invalid_card} do
      refute is_valid_card(type, invalid_card)
    end

end

Test Cases for Credit card

describe "credit_card" do
    setup do
      {:ok, type: :credit, valid_card: 123456789012, invalid_card: 1234567890} 
    end

    test "valid credit card", %{type: type, valid_card: valid_card} do
      assert is_valid_card(type, valid_card)
    end

    test "in-valid credit card", %{type: type, invalid_card: invalid_card} do
      refute is_valid_card(type, invalid_card)
    end

end

For the demo purpose, I purposely wrote some test cases to fail.

The overall file looks like in the following screenshot

basic_math_test.exs

Under the credit_card section, we are using the same setup data used for debit_card unit test cases which eventually results in failure of the test cases.

So, it will now include the value of each argument in the failure report: Let’s check that.

$ mix test

Run your test cases using the above command. You will see the similar output as in the following screenshot.

mix test … testing the file basic_math.ex

If you observe the above screenshot, Out of four(4), **two(2) **test cases are failed and you can see the arguments passed to the test case in the failure report.

arguments:

   #1
   :credit

   #2
   123467890

This kinda failure report is very useful when our function is linked with too many functions. It is hard to debug the fail cause of a unit test case when the function is dependent on many other functions. This is where the arguments play the vital role in debugging the code failures.

It is a great healthy feature. 💚

2. Running mix test with a failed flag 🚩

When you run the command mix test along with a flag--failed, It runs only the test cases that are failed in your previous attempt of mix test.

It means this time the task mix test --failed don’t execute the successful test cases again. So, we can save the time here.

The failed unit test cases are tracked and cached in a very first mix test

We are having totally 4 unit test cases in the file. But, when you added the failed option, it gives out only 2 failed unit test cases.

You can observe that in the following screenshot.

mix test — failed

Hope you liked it.

Happy long coding life… :)