String Functions

String functions allow manipulating, normalizing, trimming, and formatting character strings in locals.yml expressions and variables.yml validation conditions.

Function Index

Function	Signature	Description
`lower`	`lower(string)`	Converts all characters to lowercase.
`upper`	`upper(string)`	Converts all characters to uppercase.
`trim`	`trim(string, [cutset])`	Removes leading and trailing whitespace or specified characters.
`trimprefix`	`trimprefix(string, prefix)`	Removes the specified prefix if present.
`trimsuffix`	`trimsuffix(string, suffix)`	Removes the specified suffix if present.
`startswith`	`startswith(string, prefix)`	Returns `true` if the string starts with prefix.
`endswith`	`endswith(string, suffix)`	Returns `true` if the string ends with suffix.
`replace`	`replace(string, search, rep)`	Replaces all occurrences of a search pattern.
`split`	`split(separator, string)`	Splits a string into a list by separator.
`join`	`join(separator, list)`	Joins list elements into a single string.
`format`	`format(format, ...args)`	Formats a string using printf-style verbs (`%s`, `%d`, `%j`, `%%`).
`substr`	`substr(string, offset, len)`	Extracts a substring from an offset.

`lower`

Converts all characters in a string to lowercase.

testform functions --eval "lower('STAGING-APP')"
# => "staging-app"

locals:
  canonical_env: "${lower(var.environment)}"

`upper`

Converts all characters in a string to uppercase.

testform functions --eval "upper('qa_suite')"
# => "QA_SUITE"

`trim`

Removes leading and trailing whitespace. Optionally accepts a second argument specifying the character set to remove.

testform functions --eval "trim('   hello world   ')"
# => "hello world"

testform functions --eval "trim('---alert---', '-')"
# => "alert"

`trimprefix`

Removes the specified prefix from the beginning of the string if present.

testform functions --eval "trimprefix('https://api.example.com', 'https://')"
# => "api.example.com"

`trimsuffix`

Removes the specified suffix from the end of the string if present.

testform functions --eval "trimsuffix('tests/runs/suite.run.feature', '.run.feature')"
# => "tests/runs/suite"

`startswith`

Returns true if the string begins with the indicated prefix. Useful for input variable validation.

variable:
  api_endpoint:
    type: string
    validation:
      condition: "${startswith(var.api_endpoint, 'https://')}"
      error_message: "API URL must use the secure HTTPS protocol."

`endswith`

Returns true if the string ends with the indicated suffix.

variable:
  spec_file:
    type: string
    validation:
      condition: "${endswith(var.spec_file, '.case.feature')}"
      error_message: "Specification file must end with .case.feature."

`replace`

Replaces all occurrences of a search pattern with a replacement string.

testform functions --eval "replace('192.168.1.1', '.', '-')"
# => "192-168-1-1"

`split`

Divides a string into a list of strings using the specified delimiter.

testform functions --eval "split(',', 'smoke,regression,e2e')"
# => ["smoke", "regression", "e2e"]

`join`

Concatenates elements of a string list using a delimiter.

testform functions --eval "join(' / ', ['Checkout', 'Payments', 'Card'])"
# => "Checkout / Payments / Card"

`format`

Formats a string using C / Terraform-style format specifiers:

%s: String substitution.
%d: Integer substitution.
%j: Serialized JSON substitution.
%%: Literal % escape.

testform functions --eval "format('https://%s.example.com:%d/v1', 'api', 8080)"
# => "https://api.example.com:8080/v1"

locals:
  service_url: "${format('https://%s.%s', var.subdomain, var.domain)}"

`substr`

Extracts a substring of length len starting at offset. If offset is negative, it counts backwards from the end of the string.

testform functions --eval "substr('20261025_release', 0, 8)"
# => "20261025"

testform functions --eval "substr('file.json', -4, 4)"
# => "json"