diff --git a/Makefile b/Makefile
index a7de431..49d9550 100644
--- a/Makefile
+++ b/Makefile
@@ -62,7 +62,7 @@ sa:
 ifndef STATIC_ANALYSIS_CHECKER
 	@printf "\e[1m\e[31m%s\e[0m\n" "Shellcheck not installed: Static analysis not performed!" && exit 1
 else
-	@shellcheck ./**/*.sh -C && printf "\e[1m\e[32m%s\e[0m\n" "ShellCheck: OK!"
+	@shellcheck ./**/**/*.sh -C && printf "\e[1m\e[32m%s\e[0m\n" "ShellCheck: OK!"
 endif
 
 lint:
diff --git a/README.md b/README.md
index 8c625c5..30ef6c0 100644
--- a/README.md
+++ b/README.md
@@ -41,6 +41,24 @@ Examples:
 
 ## Env variables
 
+### RELEASE_SOURCE_BRANCH
+
+The default source branch that you want to use for your releases.
+
+> Default: `main`
+
+### RELEASE_TARGET_BRANCH
+
+The default target branch that you want to use for your releases.
+
+> Default: `prod`
+
+### RELEASE_DEVELOPMENT_BRANCH
+
+If you have a different develop branch from the source branch, you can also define it here.
+
+> Default: `main`
+
 ### RELEASE_SUCCESSFUL_TEXT
 
 Display a text at the very end of the release.
diff --git a/release b/release
index b02b053..4ffa33a 100755
--- a/release
+++ b/release
@@ -12,6 +12,7 @@ source "$RELEASE_ROOT_DIR/src/colors.sh"
 source "$RELEASE_ROOT_DIR/src/compare.sh"
 source "$RELEASE_ROOT_DIR/src/console_header.sh"
 source "$RELEASE_ROOT_DIR/src/env.sh"
+source "$RELEASE_ROOT_DIR/src/git.sh"
 source "$RELEASE_ROOT_DIR/src/io.sh"
 source "$RELEASE_ROOT_DIR/src/release.sh"
 source "$RELEASE_ROOT_DIR/src/validate.sh"
@@ -19,18 +20,9 @@ source "$RELEASE_ROOT_DIR/src/slack.sh"
 source "$RELEASE_ROOT_DIR/src/json.sh"
 source "$RELEASE_ROOT_DIR/src/main.sh"
 
-# Check if at least one argument (branch name) is passed
-if [ $# -lt 1 ]; then
-  console_header::print_help
-  exit 1
-fi
-
-SOURCE_BRANCH=${1:-SOURCE_BRANCH:-"main"}
-TARGET_BRANCH=${TARGET_BRANCH:-"prod"}
-DEVELOPMENT_BRANCH=${DEVELOPMENT_BRANCH:-"main"}
-RELEASE_SUCCESSFUL_TEXT=${RELEASE_SUCCESSFUL_TEXT:-}
-DRY_RUN=${DRY_RUN:-false}
+DRY_RUN=false
 FORCE_DEPLOY=false
+GH_CLI_INSTALLED=false
 
 while [[ $# -gt 0 ]]; do
   argument="$1"
@@ -53,33 +45,37 @@ while [[ $# -gt 0 ]]; do
       exit 0
       ;;
     --source)
-      SOURCE_BRANCH="$2"
+      RELEASE_SOURCE_BRANCH="$2"
       shift
       ;;
     --target)
-      TARGET_BRANCH="$2"
+      RELEASE_TARGET_BRANCH="$2"
       shift
       ;;
     --develop)
-      DEVELOPMENT_BRANCH="$2"
+      RELEASE_DEVELOPMENT_BRANCH="$2"
       shift
       ;;
+    *)
+      RELEASE_SOURCE_BRANCH=$argument
   esac
   shift
 done
 
-GH_CLI_INSTALLED=false
 if command -v gh &> /dev/null; then
     GH_CLI_INSTALLED=true
 fi
 
-export GH_CLI_INSTALLED
+#######################################################
+
 export DRY_RUN
+export FORCE_DEPLOY
+export GH_CLI_INSTALLED
+export RELEASE_SOURCE_BRANCH
+export RELEASE_TARGET_BRANCH
+export RELEASE_DEVELOPMENT_BRANCH
 
-main::action "$SOURCE_BRANCH" \
-  "$TARGET_BRANCH" \
-  "$DEVELOPMENT_BRANCH" \
-  "$FORCE_DEPLOY"
+main::action "$FORCE_DEPLOY"
 
 echo -e "${COLOR_GREEN}Script completed${COLOR_RESET}"
 env::render_successful_text
diff --git a/src/env.sh b/src/env.sh
index 2b3a98f..9e16ce3 100644
--- a/src/env.sh
+++ b/src/env.sh
@@ -5,6 +5,16 @@
 [[ -f ".env" ]] && source .env set
 set +o allexport
 
+_DEFAULT_SOURCE_BRANCH="main"
+_DEFAULT_TARGET_BRANCH="prod"
+_DEFAULT_DEVELOPMENT_BRANCH="main"
+_DEFAULT_SUCCESSFUL_TEXT=""
+
+: "${RELEASE_SOURCE_BRANCH:=${SOURCE_BRANCH:=$_DEFAULT_SOURCE_BRANCH}}"
+: "${RELEASE_TARGET_BRANCH:=${TARGET_BRANCH:=$_DEFAULT_TARGET_BRANCH}}"
+: "${RELEASE_DEVELOPMENT_BRANCH:=${DEVELOPMENT_BRANCH:=$_DEFAULT_DEVELOPMENT_BRANCH}}"
+: "${RELEASE_SUCCESSFUL_TEXT:=${SUCCESSFUL_TEXT:=$_DEFAULT_SUCCESSFUL_TEXT}}"
+
 function env::run_extra_confirmation() {
   local changed_files=$1
 
diff --git a/src/git.sh b/src/git.sh
new file mode 100644
index 0000000..27dfc77
--- /dev/null
+++ b/src/git.sh
@@ -0,0 +1,74 @@
+#!/bin/bash
+
+function git::status() {
+  git status
+}
+
+function git::fetch_origin() {
+  git fetch origin
+}
+
+function git::changed_files() {
+  git diff --name-only "$1".."$2"
+}
+
+function git::latest_tag() {
+  git describe --tags "$(git rev-list --tags --max-count=1)" 2>/dev/null || echo "v0"
+}
+
+function git::force_checkout() {
+  local branch_name="${1#origin/}"  # Remove 'origin/' prefix if present
+
+  if [[ "$DRY_RUN" == true ]]; then
+    echo -e "${COLOR_CYAN}--dry-run enabled. Skipping git fetch & checkout${COLOR_RESET}" \
+      "${COLOR_ORANGE}origin/$branch_name${COLOR_RESET}"
+    return
+  fi
+
+  git config advice.detachedHead false
+  [ -f .git/hooks/post-checkout ] && mv .git/hooks/post-checkout .git/hooks/post-checkout.bak
+
+  git fetch origin
+
+  if git rev-parse --verify "$branch_name" >/dev/null 2>&1; then
+    # If branch exists locally, force checkout it
+    git checkout -f "$branch_name"
+  else
+    # If branch doesn't exist, create a new local branch from the remote
+    git checkout -b "$branch_name" origin/"$branch_name"
+  fi
+
+  [ -f .git/hooks/post-checkout.bak ] && mv .git/hooks/post-checkout.bak .git/hooks/post-checkout
+  git config advice.detachedHead true
+}
+
+function git::update_develop() {
+  local develop=$1
+  local target=$2
+
+  echo -e "Merging ${COLOR_ORANGE}$target${COLOR_RESET} back to" \
+    "${COLOR_ORANGE}$develop${COLOR_RESET} (increase the release contains hotfixes" \
+    "that are not in ${COLOR_ORANGE}$develop${COLOR_RESET})"
+
+  git::force_checkout "$develop"
+  git::merge_source_to_target "$target" "$develop"
+}
+
+function git::merge_source_to_target() {
+  local source=$1
+  local target=$2
+
+  echo -e "Merging ${COLOR_ORANGE}$source${COLOR_RESET} release to ${COLOR_ORANGE}$target${COLOR_RESET}"
+
+  if [[ "$DRY_RUN" == true ]]; then
+    echo -e "${COLOR_CYAN}--dry-run enabled. Skipping git merge ($source into $target)${COLOR_RESET}"
+    return
+  fi
+
+  if ! git merge "$source"; then
+    echo -e "${COLOR_RED}Merge failed. Please resolve conflicts and try again.${COLOR_RESET}"
+    exit 1
+  fi
+
+  git push origin "$target" --no-verify
+}
diff --git a/src/io.sh b/src/io.sh
index de63e31..2b0f4e6 100644
--- a/src/io.sh
+++ b/src/io.sh
@@ -1,5 +1,4 @@
 #!/bin/bash
-set -euo pipefail
 
 # shellcheck disable=SC2155
 function io::confirm_or_exit() {
diff --git a/src/main.sh b/src/main.sh
index f7f7cd7..87a109d 100644
--- a/src/main.sh
+++ b/src/main.sh
@@ -3,10 +3,11 @@
 set -euo pipefail
 
 function main::action() {
-  local source=${1:-main}
-  local target=${2:-prod}
-  local develop=${3:-1:-main}
-  local force_release=${4:-false}
+  local force_release=${1:-false}
+
+  local source=${RELEASE_SOURCE_BRANCH:-main}
+  local target=${RELEASE_TARGET_BRANCH:-prod}
+  local develop=${RELEASE_DEVELOPMENT_BRANCH:-$source}
 
   validate::slack_configured "$force_release"
 
@@ -18,15 +19,15 @@ function main::action() {
   main::render_steps "$source" "$target" "$develop"
 
   echo -e "${COLOR_PURPLE}------------------------------------------------------------------${COLOR_RESET}"
-  git fetch origin
-  git status
+  git::fetch_origin
+  git::status
   echo -e "${COLOR_BLUE}------------------------------------------------------------------${COLOR_RESET}"
 
   echo -e "Using source branch: ${COLOR_ORANGE}$source${COLOR_RESET}"
   validate::no_diff_between_local_and_origin "$source" "$target" "$force_release"
 
-  local changed_files=$(git diff --name-only "$target".."$source")
-  local latest_tag=$(git describe --tags "$(git rev-list --tags --max-count=1)" 2>/dev/null || echo "v0")
+  local changed_files=$(git::changed_files "$target" "$source")
+  local latest_tag=$(git::latest_tag)
 
   echo -e "Current latest tag: ${COLOR_CYAN}$latest_tag${COLOR_RESET}"
   local new_tag=$(release::generate_new_tag "$latest_tag" "$changed_files")
@@ -45,19 +46,19 @@ function main::action() {
   env::run_extra_confirmation "$changed_files"
   env::run_extra_commands "$changed_files"
 
-  main::force_checkout "$target"
-  main::merge_source_to_target "$source" "$target"
+  git::force_checkout "$target"
+  git::merge_source_to_target "$source" "$target"
 
   release::create_tag "$target" "$new_tag" "$changed_files"
   release::create_github_release "$latest_tag" "$new_tag"
 
-  main::update_develop "$develop" "$target"
+  git::update_develop "$develop" "$target"
 }
 
 function main::render_steps() {
   local source=$1
-  local target=$1
-  local develop=$2
+  local target=$2
+  local develop=$3
 
   echo "This script will automate the release process and follow the following steps:"
   echo "- Define the branch to release: $source"
@@ -76,61 +77,3 @@ function main::render_steps() {
     return
   fi
 }
-
-function main::update_develop() {
-  local develop=$1
-  local target=$2
-
-  echo -e "Merging ${COLOR_ORANGE}$target${COLOR_RESET} back to" \
-    "${COLOR_ORANGE}$develop${COLOR_RESET} (increase the release contains hotfixes" \
-    "that are not in ${COLOR_ORANGE}$develop${COLOR_RESET})"
-
-  main::force_checkout "$develop"
-  main::merge_source_to_target "$target" "$develop"
-}
-
-function main::merge_source_to_target() {
-  local source=$1
-  local target=$2
-
-  echo -e "Merging ${COLOR_ORANGE}$source${COLOR_RESET} release to ${COLOR_ORANGE}$target${COLOR_RESET}"
-
-  if [[ "$DRY_RUN" == true ]]; then
-    echo -e "${COLOR_CYAN}--dry-run enabled. Skipping git merge ($source into $target)${COLOR_RESET}"
-    return
-  fi
-
-  if ! git merge "$source"; then
-    echo -e "${COLOR_RED}Merge failed. Please resolve conflicts and try again.${COLOR_RESET}"
-    exit 1
-  fi
-
-  git push origin "$target" --no-verify
-
-}
-
-function main::force_checkout() {
-  local branch_name="${1#origin/}"  # Remove 'origin/' prefix if present
-
-  if [[ "$DRY_RUN" == true ]]; then
-    echo -e "${COLOR_CYAN}--dry-run enabled. Skipping git fetch & checkout${COLOR_RESET}" \
-      "${COLOR_ORANGE}origin/$branch_name${COLOR_RESET}"
-    return
-  fi
-
-  git config advice.detachedHead false
-  [ -f .git/hooks/post-checkout ] && mv .git/hooks/post-checkout .git/hooks/post-checkout.bak
-
-  git fetch origin
-
-  if git rev-parse --verify "$branch_name" >/dev/null 2>&1; then
-    # If branch exists locally, force checkout it
-    git checkout -f "$branch_name"
-  else
-    # If branch doesn't exist, create a new local branch from the remote
-    git checkout -b "$branch_name" origin/"$branch_name"
-  fi
-
-  [ -f .git/hooks/post-checkout.bak ] && mv .git/hooks/post-checkout.bak .git/hooks/post-checkout
-  git config advice.detachedHead true
-}
diff --git a/tests/e2e/main_test.sh b/tests/e2e/main_test.sh
index 3e81b58..1fd4b00 100644
--- a/tests/e2e/main_test.sh
+++ b/tests/e2e/main_test.sh
@@ -7,5 +7,61 @@ function set_up() {
 function test_main_without_args() {
   spy gh
   spy git
-  assert_match_snapshot "$($SCRIPT)"
+  assert_match_snapshot "$($SCRIPT -h)"
+}
+
+function test_main_input_given_not_positive() {
+  skip "mocks are not ready yet to work on subshell..." && return
+  spy gh
+  spy read
+  export REPLY=n
+
+  mock io::confirm_or_exit echo confirming_io
+  mock git::status echo "mocked git::status"
+  mock git::fetch_origin echo "mocked git::fetch_origin"
+  mock git::changed_files echo "mocked git::changed_files"
+  mock git::latest_tag echo "mocked git::latest_tag"
+  mock git::force_checkout echo "mocked git::force_checkout"
+  mock git::update_develop echo "mocked git::update_develop"
+  mock git::merge_source_to_target echo "mocked git::merge_source_to_target"
+
+  assert_match_snapshot "$($SCRIPT --dry-run -f)"
+}
+
+function test_main_no_changed_files() {
+  skip "mocks are not ready yet to work on subshell..." && return
+
+  spy gh
+  spy read
+  export REPLY=y
+
+  mock io::confirm_or_exit echo confirming_io
+  mock git::status echo "mocked git::status"
+  mock git::fetch_origin echo "mocked git::fetch_origin"
+  mock git::changed_files echo "mocked git::changed_files"
+  mock git::latest_tag echo "mocked git::latest_tag"
+  mock git::force_checkout echo "mocked git::force_checkout"
+  mock git::update_develop echo "mocked git::update_develop"
+  mock git::merge_source_to_target echo "mocked git::merge_source_to_target"
+
+  assert_match_snapshot "$($SCRIPT --dry-run -f)"
+}
+
+# idea: override bashunit mock - to write to /tmp/mocks.sh
+function mock() {
+  local command=$1
+  shift
+
+  if [[ $# -gt 0 ]]; then
+    eval "function $command() { $*; }"
+  else
+    eval "function $command() { echo \"${CAT:-Mocked output}\"; }"
+  fi
+
+  export -f "${command?}"
+
+  # shellcheck disable=SC2005
+  echo "$(declare -f "$command")" >> /tmp/mocks.sh
+  chmod +x /tmp/mocks.sh
+  trap 'rm -f /tmp/mocks.sh' EXIT
 }