diff --git a/circle.yml b/circle.yml
new file mode 100644
index 0000000..8deabde
--- /dev/null
+++ b/circle.yml
@@ -0,0 +1,21 @@
+machine:
+  pre:
+    # install docker 1.7.1
+    - sudo curl -L -o /usr/bin/docker 'https://s3-external-1.amazonaws.com/circle-downloads/docker-1.7.1-circleci'; sudo chmod 0755 /usr/bin/docker; true
+  services:
+    - docker
+
+dependencies:
+  override:
+    - sudo add-apt-repository ppa:duggan/bats --yes
+    - sudo apt-get update -qq
+    - sudo apt-get install -qq bats
+    - docker pull jwilder/docker-gen
+    - docker pull nginx
+    - docker pull python:3
+    - docker pull rancher/socat-docker
+
+test:
+  override:
+    - docker build -t jwilder/nginx-proxy:bats .
+    - bats test
\ No newline at end of file
diff --git a/test/README.md b/test/README.md
new file mode 100644
index 0000000..721d436
--- /dev/null
+++ b/test/README.md
@@ -0,0 +1,14 @@
+Test suite
+==========
+
+This test suite is implemented on top of the [Bats](https://github.com/sstephenson/bats/blob/master/README.md) test framework.
+
+It is intended to verify the correct behavior of the Docker image `jwilder/nginx-proxy:bats`.
+
+Running the test suite
+----------------------
+
+Make sure you have Bats installed, then run:
+
+    docker build -t jwilder/nginx-proxy:bats .
+    bats test/
\ No newline at end of file
diff --git a/test/default-host.bats b/test/default-host.bats
new file mode 100644
index 0000000..0adf686
--- /dev/null
+++ b/test/default-host.bats
@@ -0,0 +1,38 @@
+#!/usr/bin/env bats
+load test_helpers
+
+function setup {
+	# make sure to stop any web container before each test so we don't
+	# have any unexpected contaiener running with VIRTUAL_HOST or VIRUTAL_PORT set
+	docker ps -q --filter "label=bats-type=web" | xargs -r docker stop >&2
+}
+
+
+@test "[$TEST_FILE] DEFAULT_HOST=web1.bats" {
+	SUT_CONTAINER=bats-nginx-proxy-${TEST_FILE}-1
+
+	# GIVEN a webserver with VIRTUAL_HOST set to web.bats
+	docker_clean bats-web
+	run docker run -d \
+		--label bats-type="web" \
+		--name bats-web \
+		-e VIRTUAL_HOST=web.bats \
+		--expose 80 \
+		-w /var/www \
+		python:3 \
+		python -m http.server 80
+	assert_success
+
+	# WHEN nginx-proxy runs with DEFAULT_HOST set to web.bats
+	run nginxproxy $SUT_CONTAINER -v /var/run/docker.sock:/tmp/docker.sock:ro -e DEFAULT_HOST=web.bats
+	assert_success
+	docker_wait_for_log $SUT_CONTAINER 3 "Watching docker events"
+
+	# THEN querying the proxy without Host header → 200
+	run curl_container $SUT_CONTAINER / --head
+	assert_output -l 0 $'HTTP/1.1 200 OK\r'
+
+	# THEN querying the proxy with any other Host header → 200
+	run curl_container $SUT_CONTAINER / --head --header "Host: something.I.just.made.up"
+	assert_output -l 0 $'HTTP/1.1 200 OK\r'
+}
diff --git a/test/docker.bats b/test/docker.bats
new file mode 100644
index 0000000..13d84a2
--- /dev/null
+++ b/test/docker.bats
@@ -0,0 +1,117 @@
+#!/usr/bin/env bats
+load test_helpers
+
+
+@test "[$TEST_FILE] start 2 web containers" {
+	prepare_web_container bats-web1 81 -e VIRTUAL_HOST=web1.bats
+	prepare_web_container bats-web2 82 -e VIRTUAL_HOST=web2.bats
+}
+
+
+@test "[$TEST_FILE] -v /var/run/docker.sock:/tmp/docker.sock:ro" {
+	SUT_CONTAINER=bats-nginx-proxy-${TEST_FILE}-1
+
+	# WHEN nginx-proxy runs on our docker host using the default unix socket 
+	run nginxproxy $SUT_CONTAINER -v /var/run/docker.sock:/tmp/docker.sock:ro
+	assert_success
+	docker_wait_for_log $SUT_CONTAINER 3 "Watching docker events"
+
+	# THEN
+	assert_nginxproxy_behaves $SUT_CONTAINER
+}
+
+
+@test "[$TEST_FILE] -v /var/run/docker.sock:/f00.sock:ro -e DOCKER_HOST=unix:///f00.sock" {
+	SUT_CONTAINER=bats-nginx-proxy-${TEST_FILE}-2
+
+	# WHEN nginx-proxy runs on our docker host using a custom unix socket 
+	run nginxproxy $SUT_CONTAINER -v /var/run/docker.sock:/f00.sock:ro -e DOCKER_HOST=unix:///f00.sock
+	assert_success
+	docker_wait_for_log $SUT_CONTAINER 3 "Watching docker events"
+
+	# THEN
+	assert_nginxproxy_behaves $SUT_CONTAINER
+}
+
+
+@test "[$TEST_FILE] -e DOCKER_HOST=tcp://..." {
+	SUT_CONTAINER=bats-nginx-proxy-${TEST_FILE}-3
+	# GIVEN a container exposing our docker host over TCP
+	run docker_tcp bats-docker-tcp
+	assert_success
+	sleep 1s
+
+	# WHEN nginx-proxy runs on our docker host using tcp to connect to our docker host
+	run nginxproxy $SUT_CONTAINER -e DOCKER_HOST="tcp://bats-docker-tcp:2375" --link bats-docker-tcp:bats-docker-tcp
+	assert_success
+	docker_wait_for_log $SUT_CONTAINER 3 "Watching docker events"
+	
+	# THEN
+	assert_nginxproxy_behaves $SUT_CONTAINER
+}
+
+
+@test "[$TEST_FILE] separated containers (nginx + docker-gen + nginx.tmpl)" {
+	docker_clean bats-nginx
+	docker_clean bats-docker-gen
+	
+	# GIVEN a simple nginx container
+	run docker run -d \
+		--name bats-nginx \
+		-v /etc/nginx/conf.d/ \
+		-v /etc/nginx/certs/ \
+		nginx:latest
+	assert_success
+	run retry 5 1s curl --silent --fail -A "before-docker-gen" --head http://$(docker_ip bats-nginx)/
+	assert_output -l 0 $'HTTP/1.1 200 OK\r'
+
+	# WHEN docker-gen runs on our docker host
+	run docker run -d \
+		--name bats-docker-gen \
+		-v /var/run/docker.sock:/tmp/docker.sock:ro \
+		-v $BATS_TEST_DIRNAME/../nginx.tmpl:/etc/docker-gen/templates/nginx.tmpl:ro \
+		--volumes-from bats-nginx \
+		jwilder/docker-gen:latest \
+			-notify-sighup bats-nginx \
+			-watch \
+			-only-exposed \
+			/etc/docker-gen/templates/nginx.tmpl \
+			/etc/nginx/conf.d/default.conf
+	assert_success
+	docker_wait_for_log bats-docker-gen 6 "Watching docker events"
+	
+	# Give some time to the docker-gen container to notify bats-nginx so it 
+	# reloads its config
+	sleep 2s
+
+	run docker_running_state bats-nginx
+	assert_output "true" || {
+		docker logs bats-docker-gen
+		false
+	} >&2
+	
+	# THEN
+	assert_nginxproxy_behaves bats-nginx
+}
+
+
+# $1 nginx-proxy container
+function assert_nginxproxy_behaves {
+	local -r container=$1
+
+	# Querying the proxy without Host header → 503
+	run curl_container $container / --head
+	assert_output -l 0 $'HTTP/1.1 503 Service Temporarily Unavailable\r'
+
+	# Querying the proxy with Host header → 200
+	run curl_container $container /data --header "Host: web1.bats"
+	assert_output "answer from port 81"
+
+	run curl_container $container /data --header "Host: web2.bats"
+	assert_output "answer from port 82"
+	
+	# Querying the proxy with unknown Host header → 503
+	run curl_container $container /data --header "Host: webFOO.bats" --head
+	assert_output -l 0 $'HTTP/1.1 503 Service Temporarily Unavailable\r'
+}
+
diff --git a/test/lib/README.md b/test/lib/README.md
new file mode 100644
index 0000000..bd444fd
--- /dev/null
+++ b/test/lib/README.md
@@ -0,0 +1,6 @@
+bats lib
+========
+
+found on https://github.com/sstephenson/bats/pull/110
+
+When that pull request will be merged, that lib won't be necessary anymore.
\ No newline at end of file
diff --git a/test/lib/bats/batslib.bash b/test/lib/bats/batslib.bash
new file mode 100644
index 0000000..003ada6
--- /dev/null
+++ b/test/lib/bats/batslib.bash
@@ -0,0 +1,596 @@
+#
+# batslib.bash
+# ------------
+#
+# The Standard Library is a collection of test helpers intended to
+# simplify testing. It contains the following types of test helpers.
+#
+#   - Assertions are functions that perform a test and output relevant
+#     information on failure to help debugging. They return 1 on failure
+#     and 0 otherwise.
+#
+# All output is formatted for readability using the functions of
+# `output.bash' and sent to the standard error.
+#
+
+source "${BATS_LIB}/batslib/output.bash"
+
+
+########################################################################
+#                               ASSERTIONS
+########################################################################
+
+# Fail and display a message. When no parameters are specified, the
+# message is read from the standard input. Other functions use this to
+# report failure.
+#
+# Globals:
+#   none
+# Arguments:
+#   $@ - [=STDIN] message
+# Returns:
+#   1 - always
+# Inputs:
+#   STDIN - [=$@] message
+# Outputs:
+#   STDERR - message
+fail() {
+  (( $# == 0 )) && batslib_err || batslib_err "$@"
+  return 1
+}
+
+# Fail and display details if the expression evaluates to false. Details
+# include the expression, `$status' and `$output'.
+#
+# NOTE: The expression must be a simple command. Compound commands, such
+#       as `[[', can be used only when executed with `bash -c'.
+#
+# Globals:
+#   status
+#   output
+# Arguments:
+#   $1 - expression
+# Returns:
+#   0 - expression evaluates to TRUE
+#   1 - otherwise
+# Outputs:
+#   STDERR - details, on failure
+assert() {
+  if ! "$@"; then
+    { local -ar single=(
+        'expression' "$*"
+        'status'     "$status"
+      )
+      local -ar may_be_multi=(
+        'output'     "$output"
+      )
+      local -ir width="$( batslib_get_max_single_line_key_width \
+                            "${single[@]}" "${may_be_multi[@]}" )"
+      batslib_print_kv_single "$width" "${single[@]}"
+      batslib_print_kv_single_or_multi "$width" "${may_be_multi[@]}"
+    } | batslib_decorate 'assertion failed' \
+      | fail
+  fi
+}
+
+# Fail and display details if the expected and actual values do not
+# equal. Details include both values.
+#
+# Globals:
+#   none
+# Arguments:
+#   $1 - actual value
+#   $2 - expected value
+# Returns:
+#   0 - values equal
+#   1 - otherwise
+# Outputs:
+#   STDERR - details, on failure
+assert_equal() {
+  if [[ $1 != "$2" ]]; then
+    batslib_print_kv_single_or_multi 8 \
+        'expected' "$2" \
+        'actual'   "$1" \
+      | batslib_decorate 'values do not equal' \
+      | fail
+  fi
+}
+
+# Fail and display details if `$status' is not 0. Details include
+# `$status' and `$output'.
+#
+# Globals:
+#   status
+#   output
+# Arguments:
+#   none
+# Returns:
+#   0 - `$status' is 0
+#   1 - otherwise
+# Outputs:
+#   STDERR - details, on failure
+assert_success() {
+  if (( status != 0 )); then
+    { local -ir width=6
+      batslib_print_kv_single "$width" 'status' "$status"
+      batslib_print_kv_single_or_multi "$width" 'output' "$output"
+    } | batslib_decorate 'command failed' \
+      | fail
+  fi
+}
+
+# Fail and display details if `$status' is 0. Details include `$output'.
+#
+# Optionally, when the expected status is specified, fail when it does
+# not equal `$status'. In this case, details include the expected and
+# actual status, and `$output'.
+#
+# Globals:
+#   status
+#   output
+# Arguments:
+#   $1 - [opt] expected status
+# Returns:
+#   0 - `$status' is not 0, or
+#       `$status' equals the expected status
+#   1 - otherwise
+# Outputs:
+#   STDERR - details, on failure
+assert_failure() {
+  (( $# > 0 )) && local -r expected="$1"
+  if (( status == 0 )); then
+    batslib_print_kv_single_or_multi 6 'output' "$output" \
+      | batslib_decorate 'command succeeded, but it was expected to fail' \
+      | fail
+  elif (( $# > 0 )) && (( status != expected )); then
+    { local -ir width=8
+      batslib_print_kv_single "$width" \
+          'expected' "$expected" \
+          'actual'   "$status"
+      batslib_print_kv_single_or_multi "$width" \
+          'output' "$output"
+    } | batslib_decorate 'command failed as expected, but status differs' \
+      | fail
+  fi
+}
+
+# Fail and display details if the expected does not match the actual
+# output or a fragment of it.
+#
+# By default, the entire output is matched. The assertion fails if the
+# expected output does not equal `$output'. Details include both values.
+#
+# When `-l <index>' is used, only the <index>-th line is matched. The
+# assertion fails if the expected line does not equal
+# `${lines[<index>}'. Details include the compared lines and <index>.
+#
+# When `-l' is used without the <index> argument, the output is searched
+# for the expected line. The expected line is matched against each line
+# in `${lines[@]}'. If no match is found the assertion fails. Details
+# include the expected line and `$output'.
+#
+# By default, literal matching is performed. Options `-p' and `-r'
+# enable partial (i.e. substring) and extended regular expression
+# matching, respectively. Specifying an invalid extended regular
+# expression with `-r' displays an error.
+#
+# Options `-p' and `-r' are mutually exclusive. When used
+# simultaneously, an error is displayed.
+#
+# Globals:
+#   output
+#   lines
+# Options:
+#   -l <index> - match against the <index>-th element of `${lines[@]}'
+#   -l - search `${lines[@]}' for the expected line
+#   -p - partial matching
+#   -r - extended regular expression matching
+# Arguments:
+#   $1 - expected output
+# Returns:
+#   0 - expected matches the actual output
+#   1 - otherwise
+# Outputs:
+#   STDERR - details, on failure
+#            error message, on error
+assert_output() {
+  local -i is_match_line=0
+  local -i is_match_contained=0
+  local -i is_mode_partial=0
+  local -i is_mode_regex=0
+
+  # Handle options.
+  while (( $# > 0 )); do
+    case "$1" in
+      -l)
+        if (( $# > 2 )) && [[ $2 =~ ^([0-9]|[1-9][0-9]+)$ ]]; then
+          is_match_line=1
+          local -ri idx="$2"
+          shift
+        else
+          is_match_contained=1;
+        fi
+        shift
+        ;;
+      -p) is_mode_partial=1; shift ;;
+      -r) is_mode_regex=1; shift ;;
+      --) break ;;
+      *) break ;;
+    esac
+  done
+
+  if (( is_match_line )) && (( is_match_contained )); then
+    echo "\`-l' and \`-l <index>' are mutually exclusive" \
+      | batslib_decorate 'ERROR: assert_output' \
+      | fail
+    return $?
+  fi
+
+  if (( is_mode_partial )) && (( is_mode_regex )); then
+    echo "\`-p' and \`-r' are mutually exclusive" \
+      | batslib_decorate 'ERROR: assert_output' \
+      | fail
+    return $?
+  fi
+
+  # Arguments.
+  local -r expected="$1"
+
+  if (( is_mode_regex == 1 )) && [[ '' =~ $expected ]] || (( $? == 2 )); then
+    echo "Invalid extended regular expression: \`$expected'" \
+      | batslib_decorate 'ERROR: assert_output' \
+      | fail
+    return $?
+  fi
+
+  # Matching.
+  if (( is_match_contained )); then
+    # Line contained in output.
+    if (( is_mode_regex )); then
+      local -i idx
+      for (( idx = 0; idx < ${#lines[@]}; ++idx )); do
+        [[ ${lines[$idx]} =~ $expected ]] && return 0
+      done
+      { local -ar single=(
+          'regex'  "$expected"
+        )
+        local -ar may_be_multi=(
+          'output' "$output"
+        )
+        local -ir width="$( batslib_get_max_single_line_key_width \
+                              "${single[@]}" "${may_be_multi[@]}" )"
+        batslib_print_kv_single "$width" "${single[@]}"
+        batslib_print_kv_single_or_multi "$width" "${may_be_multi[@]}"
+      } | batslib_decorate 'no output line matches regular expression' \
+        | fail
+    elif (( is_mode_partial )); then
+      local -i idx
+      for (( idx = 0; idx < ${#lines[@]}; ++idx )); do
+        [[ ${lines[$idx]} == *"$expected"* ]] && return 0
+      done
+      { local -ar single=(
+          'substring' "$expected"
+        )
+        local -ar may_be_multi=(
+          'output'    "$output"
+        )
+        local -ir width="$( batslib_get_max_single_line_key_width \
+                              "${single[@]}" "${may_be_multi[@]}" )"
+        batslib_print_kv_single "$width" "${single[@]}"
+        batslib_print_kv_single_or_multi "$width" "${may_be_multi[@]}"
+      } | batslib_decorate 'no output line contains substring' \
+        | fail
+    else
+      local -i idx
+      for (( idx = 0; idx < ${#lines[@]}; ++idx )); do
+        [[ ${lines[$idx]} == "$expected" ]] && return 0
+      done
+      { local -ar single=(
+          'line'   "$expected"
+        )
+        local -ar may_be_multi=(
+          'output' "$output"
+        )
+        local -ir width="$( batslib_get_max_single_line_key_width \
+                            "${single[@]}" "${may_be_multi[@]}" )"
+        batslib_print_kv_single "$width" "${single[@]}"
+        batslib_print_kv_single_or_multi "$width" "${may_be_multi[@]}"
+      } | batslib_decorate 'output does not contain line' \
+        | fail
+    fi
+  elif (( is_match_line )); then
+    # Specific line.
+    if (( is_mode_regex )); then
+      if ! [[ ${lines[$idx]} =~ $expected ]]; then
+        batslib_print_kv_single 5 \
+            'index' "$idx" \
+            'regex' "$expected" \
+            'line'  "${lines[$idx]}" \
+          | batslib_decorate 'regular expression does not match line' \
+          | fail
+      fi
+    elif (( is_mode_partial )); then
+      if [[ ${lines[$idx]} != *"$expected"* ]]; then
+        batslib_print_kv_single 9 \
+            'index'     "$idx" \
+            'substring' "$expected" \
+            'line'      "${lines[$idx]}" \
+          | batslib_decorate 'line does not contain substring' \
+          | fail
+      fi
+    else
+      if [[ ${lines[$idx]} != "$expected" ]]; then
+        batslib_print_kv_single 8 \
+            'index'    "$idx" \
+            'expected' "$expected" \
+            'actual'   "${lines[$idx]}" \
+          | batslib_decorate 'line differs' \
+          | fail
+      fi
+    fi
+  else
+    # Entire output.
+    if (( is_mode_regex )); then
+      if ! [[ $output =~ $expected ]]; then
+        batslib_print_kv_single_or_multi 6 \
+            'regex'  "$expected" \
+            'output' "$output" \
+          | batslib_decorate 'regular expression does not match output' \
+          | fail
+      fi
+    elif (( is_mode_partial )); then
+      if [[ $output != *"$expected"* ]]; then
+        batslib_print_kv_single_or_multi 9 \
+            'substring' "$expected" \
+            'output'    "$output" \
+          | batslib_decorate 'output does not contain substring' \
+          | fail
+      fi
+    else
+      if [[ $output != "$expected" ]]; then
+        batslib_print_kv_single_or_multi 8 \
+            'expected' "$expected" \
+            'actual'   "$output" \
+          | batslib_decorate 'output differs' \
+          | fail
+      fi
+    fi
+  fi
+}
+
+# Fail and display details if the unexpected matches the actual output
+# or a fragment of it.
+#
+# By default, the entire output is matched. The assertion fails if the
+# unexpected output equals `$output'. Details include `$output'.
+#
+# When `-l <index>' is used, only the <index>-th line is matched. The
+# assertion fails if the unexpected line equals `${lines[<index>}'.
+# Details include the compared line and <index>.
+#
+# When `-l' is used without the <index> argument, the output is searched
+# for the unexpected line. The unexpected line is matched against each
+# line in `${lines[<index>]}'. If a match is found the assertion fails.
+# Details include the unexpected line, the index where it was found and
+# `$output' (with the unexpected line highlighted in it if `$output` is
+# longer than one line).
+#
+# By default, literal matching is performed. Options `-p' and `-r'
+# enable partial (i.e. substring) and extended regular expression
+# matching, respectively. On failure, the substring or the regular
+# expression is added to the details (if not already displayed).
+# Specifying an invalid extended regular expression with `-r' displays
+# an error.
+#
+# Options `-p' and `-r' are mutually exclusive. When used
+# simultaneously, an error is displayed.
+#
+# Globals:
+#   output
+#   lines
+# Options:
+#   -l <index> - match against the <index>-th element of `${lines[@]}'
+#   -l - search `${lines[@]}' for the unexpected line
+#   -p - partial matching
+#   -r - extended regular expression matching
+# Arguments:
+#   $1 - unexpected output
+# Returns:
+#   0 - unexpected matches the actual output
+#   1 - otherwise
+# Outputs:
+#   STDERR - details, on failure
+#            error message, on error
+refute_output() {
+  local -i is_match_line=0
+  local -i is_match_contained=0
+  local -i is_mode_partial=0
+  local -i is_mode_regex=0
+
+  # Handle options.
+  while (( $# > 0 )); do
+    case "$1" in
+      -l)
+        if (( $# > 2 )) && [[ $2 =~ ^([0-9]|[1-9][0-9]+)$ ]]; then
+          is_match_line=1
+          local -ri idx="$2"
+          shift
+        else
+          is_match_contained=1;
+        fi
+        shift
+        ;;
+      -L) is_match_contained=1; shift ;;
+      -p) is_mode_partial=1; shift ;;
+      -r) is_mode_regex=1; shift ;;
+      --) break ;;
+      *) break ;;
+    esac
+  done
+
+  if (( is_match_line )) && (( is_match_contained )); then
+    echo "\`-l' and \`-l <index>' are mutually exclusive" \
+      | batslib_decorate 'ERROR: refute_output' \
+      | fail
+    return $?
+  fi
+
+  if (( is_mode_partial )) && (( is_mode_regex )); then
+    echo "\`-p' and \`-r' are mutually exclusive" \
+      | batslib_decorate 'ERROR: refute_output' \
+      | fail
+    return $?
+  fi
+
+  # Arguments.
+  local -r unexpected="$1"
+
+  if (( is_mode_regex == 1 )) && [[ '' =~ $unexpected ]] || (( $? == 2 )); then
+    echo "Invalid extended regular expression: \`$unexpected'" \
+      | batslib_decorate 'ERROR: refute_output' \
+      | fail
+    return $?
+  fi
+
+  # Matching.
+  if (( is_match_contained )); then
+    # Line contained in output.
+    if (( is_mode_regex )); then
+      local -i idx
+      for (( idx = 0; idx < ${#lines[@]}; ++idx )); do
+        if [[ ${lines[$idx]} =~ $unexpected ]]; then
+          { local -ar single=(
+              'regex'  "$unexpected"
+              'index'  "$idx"
+            )
+            local -a may_be_multi=(
+              'output' "$output"
+            )
+            local -ir width="$( batslib_get_max_single_line_key_width \
+                                "${single[@]}" "${may_be_multi[@]}" )"
+            batslib_print_kv_single "$width" "${single[@]}"
+            if batslib_is_single_line "${may_be_multi[1]}"; then
+              batslib_print_kv_single "$width" "${may_be_multi[@]}"
+            else
+              may_be_multi[1]="$( printf '%s' "${may_be_multi[1]}" \
+                                    | batslib_prefix \
+                                    | batslib_mark '>' "$idx" )"
+              batslib_print_kv_multi "${may_be_multi[@]}"
+            fi
+          } | batslib_decorate 'no line should match the regular expression' \
+            | fail
+          return $?
+        fi
+      done
+    elif (( is_mode_partial )); then
+      local -i idx
+      for (( idx = 0; idx < ${#lines[@]}; ++idx )); do
+        if [[ ${lines[$idx]} == *"$unexpected"* ]]; then
+          { local -ar single=(
+              'substring' "$unexpected"
+              'index'     "$idx"
+            )
+            local -a may_be_multi=(
+              'output'    "$output"
+            )
+            local -ir width="$( batslib_get_max_single_line_key_width \
+                                "${single[@]}" "${may_be_multi[@]}" )"
+            batslib_print_kv_single "$width" "${single[@]}"
+            if batslib_is_single_line "${may_be_multi[1]}"; then
+              batslib_print_kv_single "$width" "${may_be_multi[@]}"
+            else
+              may_be_multi[1]="$( printf '%s' "${may_be_multi[1]}" \
+                                    | batslib_prefix \
+                                    | batslib_mark '>' "$idx" )"
+              batslib_print_kv_multi "${may_be_multi[@]}"
+            fi
+          } | batslib_decorate 'no line should contain substring' \
+            | fail
+          return $?
+        fi
+      done
+    else
+      local -i idx
+      for (( idx = 0; idx < ${#lines[@]}; ++idx )); do
+        if [[ ${lines[$idx]} == "$unexpected" ]]; then
+          { local -ar single=(
+              'line'   "$unexpected"
+              'index'  "$idx"
+            )
+            local -a may_be_multi=(
+              'output' "$output"
+            )
+            local -ir width="$( batslib_get_max_single_line_key_width \
+                                "${single[@]}" "${may_be_multi[@]}" )"
+            batslib_print_kv_single "$width" "${single[@]}"
+            if batslib_is_single_line "${may_be_multi[1]}"; then
+              batslib_print_kv_single "$width" "${may_be_multi[@]}"
+            else
+              may_be_multi[1]="$( printf '%s' "${may_be_multi[1]}" \
+                                    | batslib_prefix \
+                                    | batslib_mark '>' "$idx" )"
+              batslib_print_kv_multi "${may_be_multi[@]}"
+            fi
+          } | batslib_decorate 'line should not be in output' \
+            | fail
+          return $?
+        fi
+      done
+    fi
+  elif (( is_match_line )); then
+    # Specific line.
+    if (( is_mode_regex )); then
+      if [[ ${lines[$idx]} =~ $unexpected ]] || (( $? == 0 )); then
+        batslib_print_kv_single 5 \
+            'index' "$idx" \
+            'regex' "$unexpected" \
+            'line'  "${lines[$idx]}" \
+          | batslib_decorate 'regular expression should not match line' \
+          | fail
+      fi
+    elif (( is_mode_partial )); then
+      if [[ ${lines[$idx]} == *"$unexpected"* ]]; then
+        batslib_print_kv_single 9 \
+            'index'     "$idx" \
+            'substring' "$unexpected" \
+            'line'      "${lines[$idx]}" \
+          | batslib_decorate 'line should not contain substring' \
+          | fail
+      fi
+    else
+      if [[ ${lines[$idx]} == "$unexpected" ]]; then
+        batslib_print_kv_single 5 \
+            'index' "$idx" \
+            'line'  "${lines[$idx]}" \
+          | batslib_decorate 'line should differ' \
+          | fail
+      fi
+    fi
+  else
+    # Entire output.
+    if (( is_mode_regex )); then
+      if [[ $output =~ $unexpected ]] || (( $? == 0 )); then
+        batslib_print_kv_single_or_multi 6 \
+            'regex'  "$unexpected" \
+            'output' "$output" \
+          | batslib_decorate 'regular expression should not match output' \
+          | fail
+      fi
+    elif (( is_mode_partial )); then
+      if [[ $output == *"$unexpected"* ]]; then
+        batslib_print_kv_single_or_multi 9 \
+            'substring' "$unexpected" \
+            'output'    "$output" \
+          | batslib_decorate 'output should not contain substring' \
+          | fail
+      fi
+    else
+      if [[ $output == "$unexpected" ]]; then
+        batslib_print_kv_single_or_multi 6 \
+            'output' "$output" \
+          | batslib_decorate 'output equals, but it was expected to differ' \
+          | fail
+      fi
+    fi
+  fi
+}
\ No newline at end of file
diff --git a/test/lib/bats/batslib/output.bash b/test/lib/bats/batslib/output.bash
new file mode 100644
index 0000000..aa9cb87
--- /dev/null
+++ b/test/lib/bats/batslib/output.bash
@@ -0,0 +1,264 @@
+#
+# output.bash
+# -----------
+#
+# Private functions implementing output formatting. Used by public
+# helper functions.
+#
+
+# Print a message to the standard error. When no parameters are
+# specified, the message is read from the standard input.
+#
+# Globals:
+#   none
+# Arguments:
+#   $@ - [=STDIN] message
+# Returns:
+#   none
+# Inputs:
+#   STDIN - [=$@] message
+# Outputs:
+#   STDERR - message
+batslib_err() {
+  { if (( $# > 0 )); then
+      echo "$@"
+    else
+      cat -
+    fi
+  } >&2
+}
+
+# Count the number of lines in the given string.
+#
+# TODO(ztombol): Fix tests and remove this note after #93 is resolved!
+# NOTE: Due to a bug in Bats, `batslib_count_lines "$output"' does not
+#       give the same result as `${#lines[@]}' when the output contains
+#       empty lines.
+#       See PR #93 (https://github.com/sstephenson/bats/pull/93).
+#
+# Globals:
+#   none
+# Arguments:
+#   $1 - string
+# Returns:
+#   none
+# Outputs:
+#   STDOUT - number of lines
+batslib_count_lines() {
+  local -i n_lines=0
+  local line
+  while IFS='' read -r line || [[ -n $line ]]; do
+    (( ++n_lines ))
+  done < <(printf '%s' "$1")
+  echo "$n_lines"
+}
+
+# Determine whether all strings are single-line.
+#
+# Globals:
+#   none
+# Arguments:
+#   $@ - strings
+# Returns:
+#   0 - all strings are single-line
+#   1 - otherwise
+batslib_is_single_line() {
+  for string in "$@"; do
+    (( $(batslib_count_lines "$string") > 1 )) && return 1
+  done
+  return 0
+}
+
+# Determine the length of the longest key that has a single-line value.
+#
+# This function is useful in determining the correct width of the key
+# column in two-column format when some keys may have multi-line values
+# and thus should be excluded.
+#
+# Globals:
+#   none
+# Arguments:
+#   $odd - key
+#   $even - value of the previous key
+# Returns:
+#   none
+# Outputs:
+#   STDOUT - length of longest key
+batslib_get_max_single_line_key_width() {
+  local -i max_len=-1
+  while (( $# != 0 )); do
+    local -i key_len="${#1}"
+    batslib_is_single_line "$2" && (( key_len > max_len )) && max_len="$key_len"
+    shift 2
+  done
+  echo "$max_len"
+}
+
+# Print key-value pairs in two-column format.
+#
+# Keys are displayed in the first column, and their corresponding values
+# in the second. To evenly line up values, the key column is fixed-width
+# and its width is specified with the first parameter (possibly computed
+# using `batslib_get_max_single_line_key_width').
+#
+# Globals:
+#   none
+# Arguments:
+#   $1 - width of key column
+#   $even - key
+#   $odd - value of the previous key
+# Returns:
+#   none
+# Outputs:
+#   STDOUT - formatted key-value pairs
+batslib_print_kv_single() {
+  local -ir col_width="$1"; shift
+  while (( $# != 0 )); do
+    printf '%-*s : %s\n' "$col_width" "$1" "$2"
+    shift 2
+  done
+}
+
+# Print key-value pairs in multi-line format.
+#
+# The key is displayed first with the number of lines of its
+# corresponding value in parenthesis. Next, starting on the next line,
+# the value is displayed. For better readability, it is recommended to
+# indent values using `batslib_prefix'.
+#
+# Globals:
+#   none
+# Arguments:
+#   $odd - key
+#   $even - value of the previous key
+# Returns:
+#   none
+# Outputs:
+#   STDOUT - formatted key-value pairs
+batslib_print_kv_multi() {
+  while (( $# != 0 )); do
+    printf '%s (%d lines):\n' "$1" "$( batslib_count_lines "$2" )"
+    printf '%s\n' "$2"
+    shift 2
+  done
+}
+
+# Print all key-value pairs in either two-column or multi-line format
+# depending on whether all values are single-line.
+#
+# If all values are single-line, print all pairs in two-column format
+# with the specified key column width (identical to using
+# `batslib_print_kv_single').
+#
+# Otherwise, print all pairs in multi-line format after indenting values
+# with two spaces for readability (identical to using `batslib_prefix'
+# and `batslib_print_kv_multi')
+#
+# Globals:
+#   none
+# Arguments:
+#   $1 - width of key column (for two-column format)
+#   $even - key
+#   $odd - value of the previous key
+# Returns:
+#   none
+# Outputs:
+#   STDOUT - formatted key-value pairs
+batslib_print_kv_single_or_multi() {
+  local -ir width="$1"; shift
+  local -a pairs=( "$@" )
+
+  local -a values=()
+  local -i i
+  for (( i=1; i < ${#pairs[@]}; i+=2 )); do
+    values+=( "${pairs[$i]}" )
+  done
+
+  if batslib_is_single_line "${values[@]}"; then
+    batslib_print_kv_single "$width" "${pairs[@]}"
+  else
+    local -i i
+    for (( i=1; i < ${#pairs[@]}; i+=2 )); do
+      pairs[$i]="$( batslib_prefix < <(printf '%s' "${pairs[$i]}") )"
+    done
+    batslib_print_kv_multi "${pairs[@]}"
+  fi
+}
+
+# Prefix each line read from the standard input with the given string.
+#
+# Globals:
+#   none
+# Arguments:
+#   $1 - [=  ] prefix string
+# Returns:
+#   none
+# Inputs:
+#   STDIN - lines
+# Outputs:
+#   STDOUT - prefixed lines
+batslib_prefix() {
+  local -r prefix="${1:-  }"
+  local line
+  while IFS='' read -r line || [[ -n $line ]]; do
+    printf '%s%s\n' "$prefix" "$line"
+  done
+}
+
+# Mark select lines of the text read from the standard input by
+# overwriting their beginning with the given string.
+#
+# Usually the input is indented by a few spaces using `batslib_prefix'
+# first.
+#
+# Globals:
+#   none
+# Arguments:
+#   $1 - marking string
+#   $@ - indices (zero-based) of lines to mark
+# Returns:
+#   none
+# Inputs:
+#   STDIN - lines
+# Outputs:
+#   STDOUT - lines after marking
+batslib_mark() {
+  local -r symbol="$1"; shift
+  # Sort line numbers.
+  set -- $( sort -nu <<< "$( printf '%d\n' "$@" )" )
+
+  local line
+  local -i idx=0
+  while IFS='' read -r line || [[ -n $line ]]; do
+    if (( ${1:--1} == idx )); then
+      printf '%s\n' "${symbol}${line:${#symbol}}"
+      shift
+    else
+      printf '%s\n' "$line"
+    fi
+    (( ++idx ))
+  done
+}
+
+# Enclose the input text in header and footer lines.
+#
+# The header contains the given string as title. The output is preceded
+# and followed by an additional newline to make it stand out more.
+#
+# Globals:
+#   none
+# Arguments:
+#   $1 - title
+# Returns:
+#   none
+# Inputs:
+#   STDIN - text
+# Outputs:
+#   STDOUT - decorated text
+batslib_decorate() {
+  echo
+  echo "-- $1 --"
+  cat -
+  echo '--'
+  echo
+}
\ No newline at end of file
diff --git a/test/lib/docker_helpers.bash b/test/lib/docker_helpers.bash
new file mode 100644
index 0000000..05eb0be
--- /dev/null
+++ b/test/lib/docker_helpers.bash
@@ -0,0 +1,61 @@
+## functions to help deal with docker
+
+# Removes container $1
+function docker_clean {
+	docker kill $1 &>/dev/null ||:
+	sleep .25s
+	docker rm -vf $1 &>/dev/null ||:
+	sleep .25s
+}
+
+# get the ip of docker container $1
+function docker_ip {
+	docker inspect --format '{{ .NetworkSettings.IPAddress }}' $1
+}
+
+# get the running state of container $1
+# → true/false
+# fails if the container does not exist
+function docker_running_state {
+	docker inspect -f {{.State.Running}} $1
+}
+
+# get the docker container $1 PID
+function docker_pid {
+	docker inspect --format {{.State.Pid}} $1
+}
+
+# asserts logs from container $1 contains $2
+function docker_assert_log {
+	local -r container=$1
+	shift
+	run docker logs $container
+	assert_output -p "$*"
+}
+
+# wait for container $2 to contain a given text in its log
+# $1 container
+# $2 timeout in second
+# $* text to wait for
+function docker_wait_for_log {
+	local -r container=$1
+	shift
+	local -ir timeout_sec=$1
+	shift
+	retry $(( $timeout_sec * 2 )) .5s docker_assert_log $container "$*"
+}
+
+# Create a docker container named $1 which exposes the docker host unix 
+# socket over tcp on port 2375.
+#
+# $1 container name
+function docker_tcp {
+	local container_name="$1"
+	docker_clean $container_name
+	docker run -d \
+		--name $container_name \
+		--expose 2375 \
+		-v /var/run/docker.sock:/var/run/docker.sock \
+		rancher/socat-docker
+	docker -H tcp://$(docker_ip $container_name):2375 version
+}
diff --git a/test/lib/helpers.bash b/test/lib/helpers.bash
new file mode 100644
index 0000000..dffcd66
--- /dev/null
+++ b/test/lib/helpers.bash
@@ -0,0 +1,22 @@
+## add the retry function to bats
+
+# Retry a command $1 times until it succeeds. Wait $2 seconds between retries.
+function retry {
+    local attempts=$1
+    shift
+    local delay=$1
+    shift
+    local i
+
+    for ((i=0; i < attempts; i++)); do
+        run "$@"
+        if [ "$status" -eq 0 ]; then
+            echo "$output"
+            return 0
+        fi
+        sleep $delay
+    done
+
+    echo "Command \"$@\" failed $attempts times. Status: $status. Output: $output" >&2
+    false
+}
diff --git a/test/multiple-hosts.bats b/test/multiple-hosts.bats
new file mode 100644
index 0000000..0380509
--- /dev/null
+++ b/test/multiple-hosts.bats
@@ -0,0 +1,47 @@
+#!/usr/bin/env bats
+load test_helpers
+SUT_CONTAINER=bats-nginx-proxy-${TEST_FILE}
+
+function setup {
+	# make sure to stop any web container before each test so we don't
+	# have any unexpected contaiener running with VIRTUAL_HOST or VIRUTAL_PORT set
+	docker ps -q --filter "label=bats-type=web" | xargs -r docker stop >&2
+}
+
+
+@test "[$TEST_FILE] start a nginx-proxy container" {
+	run nginxproxy $SUT_CONTAINER -v /var/run/docker.sock:/tmp/docker.sock:ro
+	assert_success
+	docker_wait_for_log $SUT_CONTAINER 3 "Watching docker events"
+}
+
+@test "[$TEST_FILE] nginx-proxy forwards requests for 2 hosts" {
+	# WHEN a container runs a web server with VIRTUAL_HOST set for multiple hosts
+	docker_clean bats-multiple-hosts-1
+	run docker run -d \
+		--label bats-type="web" \
+		--name bats-multiple-hosts-1 \
+		-e VIRTUAL_HOST=multiple-hosts-1-A.bats,multiple-hosts-1-B.bats \
+		--expose 80 \
+		-w /data \
+		python:3 python -m http.server 80
+	assert_success
+	run retry 5 1s curl_container bats-multiple-hosts-1 / --head
+	assert_output -l 0 $'HTTP/1.0 200 OK\r'
+
+	# THEN querying the proxy without Host header → 503
+	run curl_container $SUT_CONTAINER / --head
+	assert_output -l 0 $'HTTP/1.1 503 Service Temporarily Unavailable\r'
+
+	# THEN querying the proxy with unknown Host header → 503
+	run curl_container $SUT_CONTAINER /data --header "Host: webFOO.bats" --head
+	assert_output -l 0 $'HTTP/1.1 503 Service Temporarily Unavailable\r'
+
+	# THEN
+	run curl_container $SUT_CONTAINER / --head --header 'Host: multiple-hosts-1-A.bats'
+	assert_output -l 0 $'HTTP/1.1 200 OK\r' || (echo $output; echo $status; false)
+
+	# THEN
+	run curl_container $SUT_CONTAINER / --head --header 'Host: multiple-hosts-1-B.bats'
+	assert_output -l 0 $'HTTP/1.1 200 OK\r'
+}
diff --git a/test/multiple-ports.bats b/test/multiple-ports.bats
new file mode 100644
index 0000000..a711056
--- /dev/null
+++ b/test/multiple-ports.bats
@@ -0,0 +1,54 @@
+#!/usr/bin/env bats
+load test_helpers
+SUT_CONTAINER=bats-nginx-proxy-${TEST_FILE}
+
+function setup {
+	# make sure to stop any web container before each test so we don't
+	# have any unexpected contaiener running with VIRTUAL_HOST or VIRUTAL_PORT set
+	docker ps -q --filter "label=bats-type=web" | xargs -r docker stop >&2
+}
+
+
+@test "[$TEST_FILE] start a nginx-proxy container" {
+	# GIVEN nginx-proxy
+	run nginxproxy $SUT_CONTAINER -v /var/run/docker.sock:/tmp/docker.sock:ro
+	assert_success
+	docker_wait_for_log $SUT_CONTAINER 3 "Watching docker events"
+}
+
+
+@test "[$TEST_FILE] nginx-proxy defaults to the service running on port 80" {
+	# WHEN
+	prepare_web_container bats-web-${TEST_FILE}-1 "80 90" -e VIRTUAL_HOST=web.bats
+
+	# THEN 
+	assert_response_is_from_port 80
+}
+
+
+@test "[$TEST_FILE] VIRTUAL_PORT=90 while port 80 is also exposed" {
+	# GIVEN
+	prepare_web_container bats-web-${TEST_FILE}-2 "80 90" -e VIRTUAL_HOST=web.bats -e VIRTUAL_PORT=90
+
+	# THEN 
+	assert_response_is_from_port 90
+}
+
+
+@test "[$TEST_FILE] single exposed port != 80" {
+	# GIVEN
+	prepare_web_container bats-web-${TEST_FILE}-3 1234 -e VIRTUAL_HOST=web.bats
+
+	# THEN 
+	assert_response_is_from_port 1234
+}
+
+
+# assert querying nginx-proxy provides a response from the expected port of the web container
+# $1 port we are expecting an response from
+function assert_response_is_from_port {
+	local -r port=$1
+	run curl_container $SUT_CONTAINER /data --header "Host: web.bats"
+	assert_output "answer from port $port"
+}
+
diff --git a/test/test_helpers.bash b/test/test_helpers.bash
new file mode 100644
index 0000000..9063736
--- /dev/null
+++ b/test/test_helpers.bash
@@ -0,0 +1,128 @@
+# Test if requirements are met
+(
+	type docker &>/dev/null || ( echo "docker is not available"; exit 1 )
+	type curl &>/dev/null || ( echo "curl is not available"; exit 1 )
+)>&2
+
+
+# set a few global variables
+SUT_IMAGE=jwilder/nginx-proxy:bats
+TEST_FILE=$(basename $BATS_TEST_FILENAME .bats)
+
+
+# load the Bats stdlib (see https://github.com/sstephenson/bats/pull/110)
+DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
+export BATS_LIB="${DIR}/lib/bats"
+load "${BATS_LIB}/batslib.bash"
+
+
+# load additional bats helpers
+load ${DIR}/lib/helpers.bash
+load ${DIR}/lib/docker_helpers.bash
+
+
+# Define functions specific to our test suite
+
+# run the SUT docker container 
+# and makes sure it remains started
+# and displays the nginx-proxy start logs
+#
+# $1 container name
+# $@ other options for the `docker run` command
+function nginxproxy {
+	local -r container_name=$1
+	shift
+	docker_clean $container_name \
+	&& docker run -d \
+		--name $container_name \
+		"$@" \
+		$SUT_IMAGE \
+	&& wait_for_nginxproxy_container_to_start $container_name \
+	&& docker logs $container_name
+}
+
+
+# wait until the nginx-proxy container is ready to operate
+#
+# $1 container name
+function wait_for_nginxproxy_container_to_start {
+	local -r container_name=$1
+	sleep .5s  # give time to eventually fail to initialize
+
+	function is_running {
+		run docker_running_state $container_name
+		assert_output "true"
+	}
+	retry 3 1 is_running
+}
+
+
+# Send a HTTP request to container $1 for path $2 and 
+# Additional curl options can be passed as $@
+#
+# $1 container name
+# $2 HTTP path to query
+# $@ additional options to pass to the curl command
+function curl_container {
+	local -r container=$1
+	local -r path=$2
+	shift 2
+	curl --silent \
+		--connect-timeout 5 \
+		--max-time 20 \
+		"$@" \
+		http://$(docker_ip $container)${path}
+}
+
+
+# start a container running (one or multiple) webservers listening on given ports
+#
+# $1 container name
+# $2 container port(s). If multiple ports, provide them as a string: "80 90" with a space as a separator
+# $@ `docker run` additional options
+function prepare_web_container {
+	local -r container_name=$1
+	local -r ports=$2
+	shift 2
+	local -r options="$@"
+
+	local expose_option=""
+	for port in $ports; do
+		expose_option="${expose_option}--expose=$port "
+	done
+
+	(	# used for debugging purpose. Will be display if test fails
+		echo "container_name: $container_name"
+		echo "ports: $ports"
+		echo "options: $options"
+		echo "expose_option: $expose_option"
+	)>&2
+	
+	docker_clean $container_name
+
+	# GIVEN a container exposing 1 webserver on ports 1234
+	run docker run -d \
+		--label bats-type="web" \
+		--name $container_name \
+		$expose_option \
+		-w /var/www/ \
+		$options \
+		-e PYTHON_PORTS="$ports" \
+		python:3 sh -c "
+			for port in \$PYTHON_PORTS; do
+				echo starting a web server listening on port \$port;
+				mkdir /var/www/\$port
+				cd /var/www/\$port
+				echo \"answer from port \$port\" > data
+				python -m http.server \$port &
+			done
+			wait
+		"
+	assert_success
+
+	# THEN querying directly port works
+	for port in $ports; do
+		run retry 5 1s curl --silent --fail http://$(docker_ip $container_name):$port/data
+		assert_output "answer from port $port"
+	done
+}
\ No newline at end of file
diff --git a/test/wildcard-hosts.bats b/test/wildcard-hosts.bats
new file mode 100644
index 0000000..8242fc1
--- /dev/null
+++ b/test/wildcard-hosts.bats
@@ -0,0 +1,68 @@
+#!/usr/bin/env bats
+load test_helpers
+SUT_CONTAINER=bats-nginx-proxy-${TEST_FILE}
+
+function setup {
+	# make sure to stop any web container before each test so we don't
+	# have any unexpected contaiener running with VIRTUAL_HOST or VIRUTAL_PORT set
+	docker ps -q --filter "label=bats-type=web" | xargs -r docker stop >&2
+}
+
+
+@test "[$TEST_FILE] start a nginx-proxy container" {
+	# GIVEN
+	run nginxproxy $SUT_CONTAINER -v /var/run/docker.sock:/tmp/docker.sock:ro
+	assert_success
+	docker_wait_for_log $SUT_CONTAINER 3 "Watching docker events"
+}
+
+
+@test "[$TEST_FILE] VIRTUAL_HOST=*.wildcard.bats" {
+	# WHEN
+	prepare_web_container bats-wildcard-hosts-1 80 -e VIRTUAL_HOST=*.wildcard.bats
+
+	# THEN
+	assert_200 f00.wildcard.bats
+	assert_200 bar.wildcard.bats
+	assert_503 unexpected.host.bats
+}
+
+@test "[$TEST_FILE] VIRTUAL_HOST=wildcard.bats.*" {
+	# WHEN
+	prepare_web_container bats-wildcard-hosts-2 80 -e VIRTUAL_HOST=wildcard.bats.*
+
+	# THEN
+	assert_200 wildcard.bats.f00
+	assert_200 wildcard.bats.bar
+	assert_503 unexpected.host.bats
+}
+
+@test "[$TEST_FILE] VIRTUAL_HOST=~^foo\.bar\..*\.bats" {
+	# WHEN
+	prepare_web_container bats-wildcard-hosts-2 80 -e VIRTUAL_HOST=~^foo\.bar\..*\.bats
+
+	# THEN
+	assert_200 foo.bar.whatever.bats
+	assert_200 foo.bar.why.not.bats
+	assert_503 unexpected.host.bats
+
+}
+
+
+# assert that querying nginx-proxy with the given Host header produces a `HTTP 200` response
+# $1 Host HTTP header to use when querying nginx-proxy
+function assert_200 {
+	local -r host=$1
+
+	run curl_container $SUT_CONTAINER / --head --header "Host: $host"
+	assert_output -l 0 $'HTTP/1.1 200 OK\r'
+}
+
+# assert that querying nginx-proxy with the given Host header produces a `HTTP 503` response
+# $1 Host HTTP header to use when querying nginx-proxy
+function assert_503 {
+	local -r host=$1
+
+	run curl_container $SUT_CONTAINER / --head --header "Host: $host"
+	assert_output -l 0 $'HTTP/1.1 503 Service Temporarily Unavailable\r'
+}
\ No newline at end of file