intellij git

 1. show local change

• open version control panel shortcut at bottom left
• open local change tab
• commit
• revert
• show diff (green add, grey delete)

2. show file history

• vcs -> git -> show history

3. show line history

• right click gutter and enable 'annotate'

sql interview question

 1. find the 2nd largest value

select max(salary) as second_highest_salary

from employees

where salary < (select max(salary) from employees);

2. find total number and average value

select department_id, count(*) as total_employees, avg(salary) as average_salary

from employees

group by department_id;

3. find the employees who have the same job title as their manager

select e.employee_name, e.job_title
from employees e
join managers m on e.manager_id = m.manager_id
where e.job_title = m.job_title;

4. find the total revenue generated per month for a given year (e.g., 2022)

select extract(month from order_date) as month, sum(revenue) as total_revenue
from orders
where extract(year from order_date) = 2022
group by extract(month from order_date)
order by month

5. 万能公式

select t1.field_1,  aggregate(t2.field_2) as metric

from table_1 t1

join table_2 t2 on t1.field_3 = t2.field_4

group by t1.field_1                            //group field should be same as in select, otherwise make no sense

order by metric

limit 3

selenium robot

 1. sections

• lines starting with *** denote sections
• they have a special meaning and serve as a way to organise the file

*** Settings ***

*** Variables ***

*** Test Cases ***

*** Keywords *** 

2. pre-defined keyword

• selenium2Library comes with many predefined keywords like “Open Browser”

3. sample .robot file

*** Settings ***

Library           SeleniumLibrary

*** Variables ***

${URL}            https://the-internet.herokuapp.com/login

${BROWSER}        chrome

*** Test Cases ***

Login Test

    Open Browser To Login Page

    Input Credentials

    Verify Successful Login

    [Teardown]    Close Browser

*** Keywords ***

Open Browser To Login Page

    Open Browser    ${URL}    ${BROWSER}

Input Credentials

    Input Text    id=username    tomsmith

    Input Text    id=password    SuperSecretPassword!

    Click Button    css=button[type="submit"]

Verify Successful Login

    Wait Until Page Contains    Welcome to the Secure Area

    Location Should Be    https://the-internet.herokuapp.com/secure

reference

1. robot framework and selenium test automation

linux/unix interview questions

 1. difference single quote, double quote, back tick

• single quote: preserve literal value
• double quote: variable expansion and command substitution
• back tick: command substitution

2. difference between >, >>, 2>

• >: redirect stdout to file and overwrite
• >>: redirect stdout to file and append
• 2>: redirect stderr to file and overwrite

3. command1 & command2 & wait

• wait for concurrent and background running commands to finish

4. trap 'rm -f /tmp/tempfile' EXIT

• do cleanup when script exit normal/abnormally
• put this line at beginning of script

5. difference source vs exec a script

• source execute in current shell, afterwards variable and function remains
• exec create subshell to execute, afterwards nothing left

6. difference test, [], [[]]

• test and [] are the same 
• [[]] is better

jenkins

 1. terminology

• node: a machine that's capable of executing pipelines or jobs, both controller and agent(slave) are node
• executor: more like a work thread on a node
• workspace: a directory on the node where pipeline or job is run
• pipeline vs job: pipeline is more powerful and flexible, pipeline is defined using DSL as jenkinsfile in source code repo
• reuseNode true: same agent node and Docker container are used for all stages of the pipeline, and the workspace directory remains the same across all stages

2, use a dockerfile

• agent { dockerfile true }
• create dockerfile and put in root of source repo

reference

1. glossary

2. use docker

3. pipeline syntax

4. how to run a shell script in jenkins pipeline

5. how to write a pipeline script in jenkins

awk

 1. program structure

BEGIN {awk-commands}

/pattern/ {awk-commands}      // body

END {awk-commands}

2. variable

$0: a special variable in awk that represents the entire line

3. commands

awk -f command.awk marks.txt

awk '/a/{++cnt} END {print "Count = ", cnt}' marks.txt

selenium interview questions

 1. handle dynamic web elements in Selenium

• use relative xpath or css selector
• identify element based on surrounding elements
• dynamic locator, e.g. contains(), startwith(), regex

2. assert vs. verify

• verify does not stop the execution

3. handle popup, tab, window

• get the handle, then switch to

4. upload and download

• upload: sendkey() with filepath, or use AutoIT or Robot class
• download: set some preferences, click download link

5. cookies

• getCookies()
• addCookie()
• deleteCookie()

6. implicit wait, explicit wait, fluent wait

• use explicit wait instead of implicit wait, DO NOT mix them together at same time
• implicit wait poll the DOM for specified amount of time before trying to locate element
• implicit wait is disabled by default and need to be enabled
• explicit wait wait for certain condition to happen
• fluent wait is a customised explicit wait

7. action

• mouse and keyboard actions
• mouse: doubleClick(), clickAndHold(), dragAndDrop(), moveToElement(), contextClick()
• keyboard: sendKeys(), keyUp(), keyDown()

8. driver close vs quit

• close: close current window
• quit: quit session

9. alert and popup

• alert: switchTo().alert()..dismiss()/.accept()/.sendKeys()

10. account login

• navigate to login page
• use api call to get auth token, then set browser cookie
• refresh page, or navigate to the after-login page

11. selenium grid

• hub is an instance of selenium server with config to distribute test
• node is an instance of selenium server with browser capabilities that the node supports

12. handle iframe

reference

1. how to handle iFrame in selenium