Merge pull request #44 from rico-chet/refute-equal-regex

Add `refute_regex()`

4 files changed, 209 insertions, 0 deletions

diff --git a/README.md b/README.md
index 4544538..c662ab8 100644
--- a/README.md
+++ b/README.md
@@ -728,6 +728,50 @@ Note that the `BASH_REMATCH` array is available immediately after the
 assertion succeeds but is fragile, i.e. prone to being overwritten as a side
 effect of other actions.
 
+### `refute_regex`
+
+This function is similar to `refute_equal` but uses pattern matching instead of
+equality, by wrapping `! [[ value =~ pattern ]]`.
+
+Fail if the value (first parameter) matches the pattern (second parameter).
+
+```bash
+@test 'refute_regex()' {
+  refute_regex 'WhatsApp' 'Threema'
+}
+```
+
+On failure, the value, the pattern and the match are displayed.
+
+```
+@test 'refute_regex()' {
+  refute_regex 'WhatsApp' 'What.'
+}
+
+-- value matches regular expression --
+value    : WhatsApp
+pattern  : What.
+match    : Whats
+case     : sensitive
+--
+```
+
+If the value or pattern is longer than one line then it is displayed in
+*multi-line* format.
+
+An error is displayed if the specified extended regular expression is invalid.
+
+For description of the matching behavior, refer to the documentation of the
+`=~` operator in the
+[Bash manual]: https://www.gnu.org/software/bash/manual/html_node/Conditional-Constructs.html.
+
+Note that the `BASH_REMATCH` array is available immediately after the assertion
+fails but is fragile, i.e. prone to being overwritten as a side effect of other
+actions like calling `run`. Thus, it's good practice to avoid using
+`BASH_REMATCH` in conjunction with `refute_regex()`. The valuable information
+the array contains is the matching part of the value which is printed in the
+failing test log, as mentioned above.
+
 <!-- REFERENCES -->
 
 [bats]: https://github.com/bats-core/bats-core
diff --git a/load.bash b/load.bash
index a5fe0f2..c67d9e8 100644
--- a/load.bash
+++ b/load.bash
@@ -30,3 +30,4 @@ source "$(dirname "${BASH_SOURCE[0]}")/src/refute_output.bash"
 source "$(dirname "${BASH_SOURCE[0]}")/src/assert_line.bash"
 source "$(dirname "${BASH_SOURCE[0]}")/src/refute_line.bash"
 source "$(dirname "${BASH_SOURCE[0]}")/src/assert_regex.bash"
+source "$(dirname "${BASH_SOURCE[0]}")/src/refute_regex.bash"
diff --git a/src/refute_regex.bash b/src/refute_regex.bash
new file mode 100644
index 0000000..0918793
--- /dev/null
+++ b/src/refute_regex.bash
@@ -0,0 +1,66 @@
+# `refute_regex`
+#
+# This function is similar to `refute_equal` but uses pattern matching instead
+# of equality, by wrapping `! [[ value =~ pattern ]]`.
+#
+# Fail if the value (first parameter) matches the pattern (second parameter).
+#
+# ```bash
+# @test 'refute_regex()' {
+#   refute_regex 'WhatsApp' 'Threema'
+# }
+# ```
+#
+# On failure, the value, the pattern and the match are displayed.
+#
+# ```
+# @test 'refute_regex()' {
+#   refute_regex 'WhatsApp' 'What.'
+# }
+#
+# -- value matches regular expression --
+# value    : WhatsApp
+# pattern  : What.
+# match    : Whats
+# case     : sensitive
+# --
+# ```
+#
+# If the value or pattern is longer than one line then it is displayed in
+# *multi-line* format.
+#
+# An error is displayed if the specified extended regular expression is invalid.
+#
+# For description of the matching behavior, refer to the documentation of the
+# `=~` operator in the
+# [Bash manual]: https://www.gnu.org/software/bash/manual/html_node/Conditional-Constructs.html.
+#
+# Note that the `BASH_REMATCH` array is available immediately after the
+# assertion fails but is fragile, i.e. prone to being overwritten as a side
+# effect of other actions like calling `run`. Thus, it's good practice to avoid
+# using `BASH_REMATCH` in conjunction with `refute_regex()`. The valuable
+# information the array contains is the matching part of the value which is
+# printed in the failing test log, as mentioned above.
+refute_regex() {
+	local -r value="${1}"
+	local -r pattern="${2}"
+
+	if [[ '' =~ ${pattern} ]] || (( ${?} == 2 )); then
+		echo "Invalid extended regular expression: \`${pattern}'" \
+		| batslib_decorate 'ERROR: refute_regex' \
+		| fail
+	elif [[ "${value}" =~ ${pattern} ]]; then
+		if shopt -p nocasematch &>/dev/null; then
+			local case_sensitive=insensitive
+		else
+			local case_sensitive=sensitive
+		fi
+		batslib_print_kv_single_or_multi 8 \
+			'value' "${value}" \
+			'pattern'  "${pattern}" \
+			'match' "${BASH_REMATCH[0]}" \
+			'case' "${case_sensitive}" \
+		| batslib_decorate 'value matches regular expression' \
+		| fail
+	fi
+}
diff --git a/test/refute_regex.bats b/test/refute_regex.bats
new file mode 100644
index 0000000..c1fd1b2
--- /dev/null
+++ b/test/refute_regex.bats
@@ -0,0 +1,98 @@
+#!/usr/bin/env bats
+
+load test_helper
+
+#
+# Literal matching
+#
+
+# Correctness
+@test "refute_regex() <value> <pattern>: fails if a <value> substring matches extended regular expression <pattern>" {
+  run refute_regex 'abc' '^[a-z]b'
+  assert_test_fail <<'ERR_MSG'
+
+-- value matches regular expression --
+value    : abc
+pattern  : ^[a-z]b
+match    : ab
+case     : sensitive
+--
+ERR_MSG
+}
+
+@test "refute_regex() <value> <pattern>: succeeds if no <value> substring matches extended regular expression <pattern>" {
+  run refute_regex 'bcd' '^[a-z]b[c-z]+'
+  assert_test_pass
+}
+
+@test "refute_regex() <value> <pattern>: provides results in BASH_REMATCH on failure" {
+  unset -v BASH_REMATCH
+
+  refute_regex 'abcd' 'b.d' \
+  || {
+      declare -p BASH_REMATCH && \
+      [ "${BASH_REMATCH[0]}" = 'bcd' ]
+  }
+}
+
+@test "refute_regex() <value> <pattern>: matches case-insensitively when 'nocasematch' is set" {
+  shopt -s nocasematch
+
+  run refute_regex 'aBc' 'ABC'
+  assert_test_fail <<'ERR_MSG'
+
+-- value matches regular expression --
+value    : aBc
+pattern  : ABC
+match    : aBc
+case     : insensitive
+--
+ERR_MSG
+}
+
+@test "refute_regex() <value> <pattern>: outputs multi-line <value> nicely when it fails" {
+  run refute_regex $'abc\n123' '^[a-z]b[c-z]+'
+  assert_test_fail <<'ERR_MSG'
+
+-- value matches regular expression --
+value (2 lines):
+  abc
+  123
+pattern (1 lines):
+  ^[a-z]b[c-z]+
+match (1 lines):
+  abc
+case (1 lines):
+  sensitive
+--
+ERR_MSG
+
+  shopt -s nocasematch
+  run refute_regex $'aBc\n123' '^[a-z]b[c-z]+'
+  assert_test_fail <<'ERR_MSG'
+
+-- value matches regular expression --
+value (2 lines):
+  aBc
+  123
+pattern (1 lines):
+  ^[a-z]b[c-z]+
+match (1 lines):
+  aBc
+case (1 lines):
+  insensitive
+--
+ERR_MSG
+}
+
+# Error handling
+@test "refute_regex() <value> <pattern>: returns 1 and displays an error message if <pattern> is not a valid extended regular expression" {
+  run refute_regex value '[.*'
+
+  assert_test_fail <<'ERR_MSG'
+
+-- ERROR: refute_regex --
+Invalid extended regular expression: `[.*'
+--
+ERR_MSG
+}