tl;dr: Testing shell scripts made easy. Run scripts with mocks, assertions, and coverage.

• Shell interpreter
• Mock external commands with specific outputs (stdout and stderr) and exit codes
• Mock environment variables
• Mock file existence
• Assert script's exit code and output (stdout and stderr)
• Assert calls of external commands
• Generate colored coverage output or Go coverage profiles.

Download and run the install script:

curl -sSfL https://github.com/feloy/tesh/releases/latest/download/install.sh | sh

Or install with Go:

go install github.com/feloy/tesh@latest

Or build from source:

go build -o tesh .

The tesh command relies on the mvdan's Go sh library (https://github.com/mvdan/sh) to interpret and run shell scripts. tesh uses the many handlers provided by this interpreter to implement mocks, assertions and coverage.

The limitations of the interpreter are described in the library documentation (https://pkg.go.dev/mvdan.cc/sh/v3/interp):

Package interp implements an interpreter that executes shell programs. It aims to support POSIX, but its support is not complete yet. It also supports some Bash features.

The interpreter generally aims to behave like Bash, but it does not support all of its features.

The interpreter currently aims to behave like a non-interactive shell, which is how most shells run scripts, and is more useful to machines. In the future, it may gain an option to behave like an interactive shell.

To be sure that your scripts are executed in the exact same way they are tested, you can run the scripts "in production" with the tesh command:

Script (script.sh):

echo Hello World

Console:

$ tesh script.sh
Hello World

You can provide a Scenario file to tesh with the --scenarios flag. This file defines one or more scenarios, and each scenario can define mocks for external commands among other things.

When scenarios only define mocks and no expectations, tesh behaves as a normal shell interpreter, except that instead of executing mocked sub-commands, it uses the exit code and stdout and stderr defined in the scenario.

In this mode, if several scenarios are defined in the Scenario file, and you do not scpecify a scenario ID, the interpreter executes the script with the first scenario; or you can specify the scenario to execute with the --scenario flag.

Script (examples/ex1.sh):

cat /path/to/file

Scenarios (examples/ex1.yaml):

scenarios:
- id: file-exists
  description: file exists
  mocks:
  - description: the file /path/to/file exists
    command: cat
    args:
    - /path/to/file
    exit-code: 0
    stdout: some text in the file

- id: file-not-exists
  description: file does not exist
  mocks:
  - description: the file /path/to/file does not exist
    command: cat
    args:
    - /path/to/file
    exit-code: 1
    stderr: the file /path/to/file does not exist

In this example, the script is executed with the first scenario, and because the sub-command cat /path/to/file is mocked, the interpreter does not call the cat command, but behaves as if the command had exited with the status code 0 and had written some text in the file in its stdout.

Console:

$ tesh examples/ex1.sh \
    --scenarios examples/ex1.yaml
some text in the file
$ echo $?
0

In this example, the script is executed with the scenario file-exists, as in the previous example.

Console:

$ tesh examples/ex1.sh \
    --scenarios examples/ex1.yaml \
    --scenario file-exists
some text in the file
$ echo $?
0

In this example, the script is executed with the scenario file-not-exists. The sub-command cat /path/to/file being mocked, the interpreter does not call the cat command, but behaves as if the command had exited with the status code 1 and had written the file /path/to/file does not exist in its stderr. Because this sub-command is the latest one in the script and terminates with a status code 1, the script terminates with the status code 1.

Console:

$ tesh examples/ex1.sh \
    --scenarios examples/ex1.yaml \
    --scenario file-not-exists
the file /path/to/file does not exist
$ echo $?
1

A scenario can define one or more environment variables.

Script (examples/ex10.sh):

echo -n $MYVAR

Scenarios (examples/ex10.yaml):

scenarios:
- id: env-not-set
  description: MYVAR env is not set
- id: env-is-set
  description: MYVAR is set with myvalue
  envs:
  - MYVAR=myvalue

In this example, MYVAR is not defined, nothing is displayed.

Console:

$ tesh examples/ex10.sh \
    --scenarios examples/ex10.yaml \
    --scenario env-not-set

In this example, MYVAR is mocked by the scenario:

Console:

$ tesh examples/ex10.sh \
    --scenarios examples/ex10.yaml \
    --scenario env-is-set
myvalue

In this example, MYVAR is defined and not mocked, its original value is displayed:

Console:

$ MYVAR=originalValue tesh examples/ex10.sh \
    --scenarios examples/ex10.yaml \
    --scenario env-not-set
originalValue

In this example, MYVAR is defined, and is also mocked by the scenario; the value displayed is the one provided by the mock:

Console:

$ MYVAR=originalValue tesh examples/ex10.sh \
    --scenarios examples/ex10.yaml \
    --scenario env-is-set
myvalue

A scenario can mock the existence of files.

Script (examples/ex11.sh):

[ -f ./path/to/file ] && echo -n "file exists" || echo -n "file does not exist"

Scenarios (examples/ex11.yaml):

scenarios:
- id: file-exists
  description: file exists
  files:
  - path: ./path/to/file
    exists: true
- id: file-not-exists
  description: file does not exist
  files:
  - path: ./path/to/file
    exists: false

In this example, the file is mocked as existing:

Console:

$ tesh examples/ex11.sh \
    --scenarios examples/ex11.yaml \
    --scenario file-exists
file exists

In this example, the file is mocked as non existing:

Console:

$ tesh examples/ex11.sh \
    --scenarios examples/ex11.yaml \
    --scenario file-not-exists
file does not exist

Scenarios can define assertions in addition to mocks. When all scenarios of a Scenario file provide assertions, the script is interpreted for each of the scenarios.

In this mode, all the scenarios are executed, and the exit code of tesh is 0 if and only if all assertions pass, or 1 otherwise. Also, the stdout and stderr for scenarios are discarded, and the result of the assertions are displayed instead.

In this example, the script is executed for all the scenarios of the Scenario file, and the results of the assertions are displayed:

Script (examples/ex2.sh):

cat /path/to/file

Scenarios (not complete, see complete file in ./examples/ex2.yaml):

scenarios:
- id: file-exists
  description: file exists
  mocks:
  - description: the file /path/to/file exists
    command: cat
    args:
    - /path/to/file
    exit-code: 0
    stdout: some text in the file
  expect:
    exit-code: 0
    stdout: some text in the file
    stderr: ""

Console:

$ tesh examples/ex2.sh \
    --scenarios examples/ex2.yaml 
Scenario: file-exists
Scenario: file-not-exists
Scenario: file-not-exists-failing-exit-code
Exit Code: expected 0, actual 1
Scenario: file-not-exists-failing-stdout
Stdout: expected "some wrong expect", actual ""
Scenario: file-not-exists-failing-stderr
Stderr: expected "some wrong stderr", actual "the file /path/to/file does not exist"

A scenario can assert that a sub-command has been called a specific number of times.

Script (examples/ex3.sh):

if ls /file/exists; then
    cat /file/exists
fi

Scenarios (not complete, see complete file in ./examples/ex3.yaml):

scenarios:
- id: file-exists
  description: file exists
  mocks:
  - description: the file /file/exists exists
    command: ls
    args:
    - /file/exists
    exit-code: 0
  - description: the file /file/exists has a content
    command: cat
    args:
    - /file/exists
    exit-code: 0
    stdout: some text in the file
  expect:
    exit-code: 0
    stdout: some text in the file
    stderr: ""
    calls:
    - command: cat
      args:
      - /file/exists
      called: 1

Console:

$ tesh examples/ex3.sh \
    --scenarios examples/ex3.yaml 
Scenario: file-exists
Scenario: file-not-exists
Scenario: file-not-exists-failing-call
Call: cat [/file/exists], expected 1 calls, actual 0 calls
Scenario: file-exists-failing-call
Call: cat [/file/exists], expected 0 calls, actual 1 calls

tesh <script file> \
  [--scenarios <scenarios file> [--scenario <scenario id>] ] \
  [--coverage[=<file>]]

Flags:

• --scenarios: YAML file defining scenarios. If omitted, the script is only executed.
• --scenario: Run a single scenario by id (requires --scenarios).
• --coverage: Show colored coverage on stdout (suppresses normal stdout/stderr).
• --coverage=<file>: Write Go coverage.txt style output to the given file.

Top-level scenarios is a list of test scenarios. Each scenario supports:

• id (string, required)
• description (string, optional)
• mocks (list) to fake external commands
• envs (list) to set environment variables
• files (list) to fake file existence
• expect (object) for assertions

Sub-commands Mocks:

mocks:
  - description: the file /path/to/file exists
    command: cat
    args: [/path/to/file]
    exit-code: 0
    stdout: some text in the file
    stderr: ""

Environment variables:

envs:
  - MYVAR=myvalue

File existence:

files:
  - path: ./path/to/file
    exists: true
  - path: ./path/to/other/file
    exists: false

Assertions:

expect:
  exit-code: 0
  stdout: "hello"
  stderr: ""
  calls:
    - command: cat
      args: [/path/to/file]
      called: 1

Use --coverage to render the script with covered lines highlighted in green and uncovered in red.

Use --coverage=coverage.txt to create a Go coverprofile compatible file.

Coverage can be used in any mode (interpreter mode without scenarios, or with scenarios and with or without assertions).

Apache 2.0. See LICENSE.