Add diffing support to bash tests

[MichaelDimmitt]

Diffing is easy to attain in bats
If you add printDiff to every function.
It will only show the output if the test fails.

curious if @IsaacG has thoughts.

by changing

@test "a name given" {
  [[ $BATS_RUN_SKIPPED == true  ]] || skip
  run two_fer Alice
  [[ $status -eq 0 ]]
  [[ $output == "One for Alice, one for me." ]]
}

printDiff(){
  echo output;
  echo "$output";
  echo ;
  echo expected;
  echo "$expected;
}

@test "a name given" {
  [[ $BATS_RUN_SKIPPED == true  ]] || skip
  run two_fer Alice

  expected=$(cat <<-END
One for Alice, one for me.
END
  )

  printDiff
  [[ $status -eq 0 ]]
  [[ "$output" ==  "$expected" ]]
}

This actually just saved me on a project.
And I am sourcing the scripts like libs as is proposed in the pending pr
#373

[IsaacG]

My name was mentioned?

Drop the trailing semicolons. Use snake case naming consistently, including function names. Prefer printf over echo. Replace your $(cat <<<END ... foo) with "foo". Prefer (( over [[ for numeric tests (-eq 0). Only print diff when there is a diff.

[IsaacG]

If you're going to show diffs, you may want to actually show the diff, not just the want/expect. diff is usually installed on most boxes that support bash. Maybe diff -u0 <("$want") <("$got")

[MichaelDimmitt]

Sorry about the mention, you always give great feedback
thanks for the insight I will try it out diff -u0 <("$want") <("$got")

[IsaacG]

@MichaelDimmitt Feel free to mention me any time you want someone pedantic to nitpick your shell code :)

[MichaelDimmitt]

Went with cmp for readibility purposes

also started a discussion on bats-core 🎉 bats-core/bats-core#490

printDiff(){
  echo ;
  echo output;
  echo "$output";
  echo ;
  echo expected;
  echo "$expected";
  echo ;
  cmp <(echo "$output") <(echo "$expected") | cut -c 23-;
  echo ;
}

@test "a failure on line 1" {
  run bash two_fer.sh Alice
  expected=$(cat <<-END
test should fail
this is some text
END
  )
  output=$(cat <<-END
test should pass
this is some text
END
  )
  printDiff
  [[ "$output" == "$expected" ]]
}
@test "a failure on line 2" {
  run bash two_fer.sh Alice
  expected=$(cat <<-END
this is some text
test should fail
END
  )
  output=$(cat <<-END
this is some text
test should pass
END
  )
  printDiff
  [[ "$output" == "$expected" ]]
}
@test "a bad diff occurs if expected is 2 lines but output is 1 line" {
  run bash two_fer.sh Alice
  expected=$(cat <<-END
this is some text
test should fail
END
  )
  output=$(cat <<-END
this is some text
END
  )
  printDiff
  [[ "$output" == "$expected" ]]
}

[IsaacG]

On a successful test, will this echo the output two times?

[MichaelDimmitt]

If the test passes the terminal does not output the results of echo from printDiff

The output only shows when the bash test fails.

[glennj]

I'm coming around to this. With the v3 release of exercism, showing students that [[ $output == $expected ]] fails is just insufficient information.