refactor: de-duplicate func for checking if Docker Compose supports using cache_from & cache_to

Author: tomowatt

lib/shared.bash

@@ -133,11 +133,15 @@ function build_image_override_file() {
     "$(docker_compose_config_version)" "$@"
 }
 
-# Checks that a specific version of docker-compose supports cache_from
+# Checks that a specific version of docker-compose supports cache_from and cache_to
 function docker_compose_supports_cache() {
   local version="$1"
   if [[ "$version" == 1* || "$version" =~ ^(2|3)(\.[01])?$ ]] ; then
-    return 1
+    echo "Unsupported Docker Compose config file version: $version"
+    echo "The 'cache_from' option can only be used with Compose file versions 2.2 or 3.2 and above."
+    echo "For more information on Docker Compose configuration file versions, see:"
+    echo "https://docs.docker.com/compose/compose-file/compose-versioning/#versioning"
+    exit 1
   fi
 }
 
@@ -216,13 +220,7 @@ function build_image_override_file_with_version() {
     fi
 
     if [[ "$cache_from_amt" -gt 0 ]] ; then
-      if ! docker_compose_supports_cache "$version" ; then
-        echo "Unsupported Docker Compose config file version: $version"
-        echo "The 'cache_from' option can only be used with Compose file versions 2.2 or 3.2 and above."
-        echo "For more information on Docker Compose configuration file versions, see:"
-        echo "https://docs.docker.com/compose/compose-file/compose-versioning/#versioning"
-        exit 1
-      fi
+      docker_compose_supports_cache "$version"
 
       printf "      cache_from:\\n"
       for cache_from_i in "${cache_from[@]}"; do
@@ -231,13 +229,7 @@ function build_image_override_file_with_version() {
     fi
 
     if [[ "$cache_to_amt" -gt 0 ]] ; then
-      if ! docker_compose_supports_cache "$version" ; then
-        echo "Unsupported Docker Compose config file version: $version"
-        echo "The 'cache_to' option can only be used with Compose file versions 2.2 or 3.2 and above."
-        echo "For more information on Docker Compose configuration file versions, see:"
-        echo "https://docs.docker.com/compose/compose-file/compose-versioning/#versioning"
-        exit 1
-      fi
+      docker_compose_supports_cache "$version"
 
       printf "      cache_to:\\n"
       for cache_to_i in "${cache_to[@]}"; do

tests/docker-compose-config.bats

@@ -81,7 +81,7 @@ load '../lib/shared'
   assert_output "2.0"
 }
 
-@test "Whether docker-compose supports cache_from directive" {
+@test "Whether docker-compose supports cache_from and cache_to directive" {
   run docker_compose_supports_cache ""
   assert_success