Environment variable expansion echo $HOME

[superxcgm]

Epic

Process

Description

For good user experience, user can add chain commands using pipeline

AC

1. Plain $ENV with value
   Given: Environment variable XXX exist (For example: $HOME)
   When: User type echo $XXX, and hit <enter>
   Then: shell should replace $XXX with it's value, and pass this argument to command echo.

2. Plain $ENV with no value
   Given: Environment variable XXX not exist (For example: $haha)
   When: User type echo $XXX, and hit <enter>
   Then: shell should replace $XXX with empty string, and pass this argument to command echo.

3. $ENV enclose with single quotation marks
   Given: No matter environment XXX exist or not.
   When: User type echo '$XXX', and hit <enter>
   Then: shell should not replace $XXX with anything, and pass $XXX as argument to command echo.

4. $ENV enclose with double quotation marks
   Given: Environment variable XXX exist (For example: $HOME), and environment variable YYY not exist.
   When: User type echo "$XXX $YYY", and hit <enter>
   Then: shell should replace $XXX with it's value, and replace $YYY with empty string, and pas argument {some value} to command echo.

[superxcgm]

QA

1. Plain $ENV with value
   Given: Environment variable XXX exist (For example: $HOME)
   When: User type echo $XXX, and hit <enter>
   Then: ✅shell should replace $XXX with it's value, and pass this argument to command echo.

2. Plain $ENV with no value
   Given: Environment variable XXX not exist (For example: $haha)
   When: User type echo $XXX, and hit <enter>
   Then: ✅shell should replace $XXX with empty string, and pass this argument to command echo.

3. $ENV enclose with single quotation marks
   Given: No matter environment XXX exist or not.
   When: User type echo '$XXX', and hit <enter>
   Then: ✅shell should not replace $XXX with anything, and pass $XXX as argument to command echo.

4. $ENV enclose with double quotation marks
   Given: Environment variable XXX exist (For example: $HOME), and environment variable YYY not exist.
   When: User type echo "$XXX $YYY", and hit <enter>
   Then: ✅shell should replace $XXX with it's value, and replace $YYY with empty string, and pas argument {some value} to command echo.