Solved hamming in Bash

bash/hamming/hamming.bats

@@ -0,0 +1,94 @@
+#!/usr/bin/env bats
+load bats-extra
+
+# local version: 2.3.0.3
+# 
+# bash-specific test: Input validation, proper quoting
+
+@test 'empty strands' {
+  #[[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh '' ''
+  assert_success
+  assert_output "0"
+}
+
+@test 'single letter identical strands' {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh 'A' 'A'
+  assert_success
+  assert_output "0"
+}
+
+@test 'single letter different strands' {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh 'G' 'T'
+  assert_success
+  assert_output "1"
+}
+
+@test 'long identical strands' {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh 'GGACTGAAATCTG' 'GGACTGAAATCTG'
+  assert_success
+  assert_output "0"
+}
+
+@test 'long different strands' {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh 'GGACGGATTCTG' 'AGGACGGATTCT'
+  assert_success
+  assert_output "9"
+}
+
+@test 'disallow first strand longer' {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh 'AATG' 'AAA'
+  assert_failure
+  assert_output --partial "strands must be of equal length"
+}
+
+@test 'disallow second strand longer' {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh 'ATA' 'AGTG'
+  assert_failure
+  assert_output --partial "strands must be of equal length"
+}
+
+@test 'disallow left empty strand' {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh '' 'G'
+  assert_failure
+  assert_output --partial "strands must be of equal length"
+}
+
+@test 'disallow right empty strand' {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh 'G' ''
+  assert_failure
+  assert_output --partial "strands must be of equal length"
+}
+
+@test "no input" {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh
+  assert_failure
+  assert_output "Usage: hamming.sh <string1> <string2>"
+}
+
+@test "invalid input" {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh 'A'
+  assert_failure
+  assert_output "Usage: hamming.sh <string1> <string2>"
+}
+
+# Within [[...]] the == operator is a _pattern matching_ operator.
+# To test for string equality, the right-hand side must be
+# quoted to prevent interpretation as a glob-style pattern.
+
+@test "expose subtle '[[ \$x == \$y ]]' bug" {
+  [[ $BATS_RUN_SKIPPED == "true" ]] || skip
+  run bash hamming.sh 'AAA' 'A?A'
+  assert_success
+  assert_output "1"
+}