(maint) Prefer apt-get to apt

For the couple of package manager operations in common.sh, apt had
preference before apt-get when searching for a system tool. But, from
what I've read, apt is not a replacement for apt-get, and the
expectation is not that newer Debian systems will eventually have apt
instead of apt-get. The apt tool is intended as a more user friendly
interface, while apt-get remains a stabler UI and more complete toolset
better suited for scripting. For this particular script, we aren't doing
any parsing, so it's academic. But given that we're not relying on a
behavior difference between the two, I've switched the order to favor
apt-get to adhere to the spirit of their differences.

I'm actually not aware of an installation where you would have apt-get
without apt or vice-versa, so a fallback may be unnecessary as well, but
there is undoubtadely some edge case somewhere...

Author: jpartlow

files/common.sh

@@ -339,10 +339,10 @@ install_package() {
 
   case ${_os_family} in
     debian|ubuntu)
-      if exists 'apt'; then
-        exec_and_capture apt install -y "${_package_and_version}"
-      elif exists 'apt-get'; then
+      if exists 'apt-get'; then
         exec_and_capture apt-get install -y "${_package_and_version}"
+      elif exists 'apt'; then
+        exec_and_capture apt install -y "${_package_and_version}"
       else
         fail "Unable to install ${_package}. Neither apt nor apt-get are installed."
       fi
@@ -363,10 +363,10 @@ install_package() {
 
 # Update the package manager cache.
 refresh_package_cache() {
-  if exists 'apt'; then
-    exec_and_capture apt update
-  elif exists 'apt-get'; then
+  if exists 'apt-get'; then
     exec_and_capture apt-get update
+  elif exists 'apt'; then
+    exec_and_capture apt update
   elif exists 'dnf'; then
     exec_and_capture dnf clean all
   elif exists 'yum'; then

spec/unit/bash/common_sh_spec.rb

@@ -329,50 +329,50 @@
 
       before do
         mock_facts_task_bash_sh(os)
-        allow_script.to receive_command(:apt).and_exec('echo "apt given: $*"')
+        allow_script.to receive_command('apt-get').and_exec('echo "apt-get given: $*"')
       end
 
       it 'installs a package' do
         output, status = test('install_package foo')
 
-        expect(output).to include('apt given: install -y foo')
+        expect(output).to include('apt-get given: install -y foo')
         expect(status.success?).to be(true)
       end
 
       it 'installs a package with a version' do
         output, status = test('install_package foo 1.2.3')
 
         expect(status.success?).to be(true)
-        expect(output).to include('apt given: install -y foo=1.2.3-1+ubuntu24.04')
+        expect(output).to include('apt-get given: install -y foo=1.2.3-1+ubuntu24.04')
       end
 
       it 'installs a deb with full package version given' do
         output, status = test('install_package foo 1.2.3-1something')
 
         expect(status.success?).to be(true)
-        expect(output).to include('apt given: install -y foo=1.2.3-1something')
+        expect(output).to include('apt-get given: install -y foo=1.2.3-1something')
       end
 
       it 'fails if package manager fails' do
-        allow_script.to receive_command(:apt).and_exec(<<~EOF)
-          echo 'apt failed'
+        allow_script.to receive_command('apt-get').and_exec(<<~EOF)
+          echo 'apt-get failed'
           return 1
         EOF
 
         output, status = test('install_package doesnotexist')
 
         expect(status.success?).to be(false)
-        expect(output).to include('apt failed')
+        expect(output).to include('apt-get failed')
       end
 
       it 'falls back to apt-get' do
-        behave_as_if_command_does_not_exist(:apt)
-        allow_script.to receive_command('apt-get').and_exec('echo "apt-get given: $*"')
+        behave_as_if_command_does_not_exist('apt-get')
+        allow_script.to receive_command(:apt).and_exec('echo "apt given: $*"')
 
         output, status = test('install_package foo')
 
         expect(status.success?).to be(true)
-        expect(output).to include('apt-get given: install -y foo')
+        expect(output).to include('apt given: install -y foo')
       end
 
       it 'fails if neither apt nor apt-get are available' do