diff --git a/action.yml b/action.yml
index f76d9af..19e3b00 100644
--- a/action.yml
+++ b/action.yml
@@ -85,5 +85,5 @@ runs:
           "${{ inputs.composer-options }}" \
           "${{ inputs.working-directory }}" \
           "${{ steps.php.outputs.path }}" \
-          "${{ steps.composer.outputs.command }}" \
+          "${{ steps.composer.outputs.composer_command }}" \
           "${{ steps.composer.outputs.lock }}"
diff --git a/bin/cache_key.sh b/bin/cache_key.sh
index 966e852..f9da134 100755
--- a/bin/cache_key.sh
+++ b/bin/cache_key.sh
@@ -57,7 +57,7 @@ cache_key="$(make_key "${key[@]}")"
 echo "::debug::Cache primary key is '${cache_key}'"
 echo "::debug::Cache restore keys are '$(join_by ", " "${uniq_restore_key[@]}")'"
 
-echo "::set-output name=key::${cache_key}"
+echo "key=${cache_key}" >> "${GITHUB_OUTPUT}"
 
 # Use an environment variable to capture the multiline restore key.
 # See: https://docs.github.com/en/actions/learn-github-actions/workflow-commands-for-github-actions#multiline-strings
diff --git a/bin/composer_paths.sh b/bin/composer_paths.sh
index 8c327ff..4d96a68 100755
--- a/bin/composer_paths.sh
+++ b/bin/composer_paths.sh
@@ -53,7 +53,9 @@ echo "::debug::${composer_version}"
 echo "::debug::Composer cache directory found at '${cache_dir}'"
 echo "::debug::File composer.json found at '${composer_json}'"
 echo "::debug::File composer.lock path computed as '${composer_lock}'"
-echo "::set-output name=command::${composer_path}"
-echo "::set-output name=cache-dir::${cache_dir}"
-echo "::set-output name=json::${composer_json}"
-echo "::set-output name=lock::${composer_lock}"
+{
+    echo "composer_command=${composer_path}"
+    echo "cache-dir=${cache_dir}"
+    echo "json=${composer_json}"
+    echo "lock=${composer_lock}"
+} >> "${GITHUB_OUTPUT}"
diff --git a/bin/php_version.sh b/bin/php_version.sh
index 746c05c..e637e03 100755
--- a/bin/php_version.sh
+++ b/bin/php_version.sh
@@ -16,5 +16,5 @@ php_version=$($php_path -r 'echo phpversion();')
 
 echo "::debug::PHP path is '${php_path}'"
 echo "::debug::PHP version is '${php_version}'"
-echo "::set-output name=path::${php_path}"
-echo "::set-output name=version::${php_version}"
+echo "path=${php_path}" >> "${GITHUB_OUTPUT}"
+echo "version=${php_version}" >> "${GITHUB_OUTPUT}"
diff --git a/bin/should_cache.sh b/bin/should_cache.sh
index 33c2c61..95cbcd0 100755
--- a/bin/should_cache.sh
+++ b/bin/should_cache.sh
@@ -15,4 +15,4 @@ if [ $should_cache -eq 0 ]; then
 fi
 
 echo "::debug::We ${will_cache} the dependencies because ignore-cache is set to '${ignore_cache}'"
-echo "::set-output name=do-cache::${should_cache}"
+echo "do-cache=${should_cache}" >> "${GITHUB_OUTPUT}"
diff --git a/tests/expect/cache_key_01.exp b/tests/expect/cache_key_01.exp
index 63e402b..ba9c4eb 100755
--- a/tests/expect/cache_key_01.exp
+++ b/tests/expect/cache_key_01.exp
@@ -1,17 +1,23 @@
 #!/usr/bin/env -S expect -f
 
+# For testing environment variables written to GITHUB_ENV
 set gitHubEnvFile cache_key_01.txt
 set ::env(GITHUB_ENV) $gitHubEnvFile
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile cache_key_output_01.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/cache_key.sh
 match_max 100000
 
 expect -exact "::debug::Cache primary key is 'php-composer-locked'"
 expect -exact "::debug::Cache restore keys are 'php-composer-locked-'"
-expect -exact "::set-output name=key::php-composer-locked"
+
 expect eof
 
+# Confirm environment variables.
 set fp [open $gitHubEnvFile r]
 set fileData [read $fp]
 close $fp
@@ -27,5 +33,19 @@ if { $expectedValue != $fileData } {
     exit 1
 }
 
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "key=php-composer-locked\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
 # Clean up
 file delete $gitHubEnvFile
+file delete $gitHubOutputFile
diff --git a/tests/expect/cache_key_02.exp b/tests/expect/cache_key_02.exp
index c7a5b20..dee529b 100755
--- a/tests/expect/cache_key_02.exp
+++ b/tests/expect/cache_key_02.exp
@@ -1,17 +1,22 @@
 #!/usr/bin/env -S expect -f
 
+# For testing environment variables written to GITHUB_ENV
 set gitHubEnvFile cache_key_02.txt
 set ::env(GITHUB_ENV) $gitHubEnvFile
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile cache_key_output_02.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/cache_key.sh "Linux" "8.1.1" "" "" "long-files-hash"
 match_max 100000
 
 expect -exact "::debug::Cache primary key is 'Linux-php-8.1.1-composer-locked-long-files-hash'"
 expect -exact "::debug::Cache restore keys are 'Linux-php-8.1.1-composer-locked-'"
-expect -exact "::set-output name=key::Linux-php-8.1.1-composer-locked-long-files-hash"
 expect eof
 
+# Confirm environment variables.
 set fp [open $gitHubEnvFile r]
 set fileData [read $fp]
 close $fp
@@ -27,5 +32,19 @@ if { $expectedValue != $fileData } {
     exit 1
 }
 
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "key=Linux-php-8.1.1-composer-locked-long-files-hash\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
 # Clean up
 file delete $gitHubEnvFile
+file delete $gitHubOutputFile
diff --git a/tests/expect/cache_key_03.exp b/tests/expect/cache_key_03.exp
index 58bfaf6..5b43fac 100755
--- a/tests/expect/cache_key_03.exp
+++ b/tests/expect/cache_key_03.exp
@@ -1,17 +1,22 @@
 #!/usr/bin/env -S expect -f
 
+# For testing environment variables written to GITHUB_ENV
 set gitHubEnvFile cache_key_03.txt
 set ::env(GITHUB_ENV) $gitHubEnvFile
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile cache_key_output_03.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/cache_key.sh "Linux" "8.1.1" "locked" "" "long-files-hash"
 match_max 100000
 
 expect -exact "::debug::Cache primary key is 'Linux-php-8.1.1-composer-locked-long-files-hash'"
 expect -exact "::debug::Cache restore keys are 'Linux-php-8.1.1-composer-locked-'"
-expect -exact "::set-output name=key::Linux-php-8.1.1-composer-locked-long-files-hash"
 expect eof
 
+# Confirm environment variables.
 set fp [open $gitHubEnvFile r]
 set fileData [read $fp]
 close $fp
@@ -27,5 +32,19 @@ if { $expectedValue != $fileData } {
     exit 1
 }
 
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "key=Linux-php-8.1.1-composer-locked-long-files-hash\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
 # Clean up
 file delete $gitHubEnvFile
+file delete $gitHubOutputFile
diff --git a/tests/expect/cache_key_04.exp b/tests/expect/cache_key_04.exp
index 9580171..1020a8b 100755
--- a/tests/expect/cache_key_04.exp
+++ b/tests/expect/cache_key_04.exp
@@ -1,17 +1,22 @@
 #!/usr/bin/env -S expect -f
 
+# For testing environment variables written to GITHUB_ENV
 set gitHubEnvFile cache_key_04.txt
 set ::env(GITHUB_ENV) $gitHubEnvFile
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile cache_key_output_04.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/cache_key.sh "Linux" "8.1.1" "lowest" "--ignore-platform-reqs --optimize-autoloader" "long-files-hash"
 match_max 100000
 
 expect -exact "::debug::Cache primary key is 'Linux-php-8.1.1-composer---ignore-platform-reqs---optimize-autoloader-lowest-long-files-hash'"
 expect -exact "::debug::Cache restore keys are 'Linux-php-8.1.1-composer---ignore-platform-reqs---optimize-autoloader-lowest-'"
-expect -exact "::set-output name=key::Linux-php-8.1.1-composer---ignore-platform-reqs---optimize-autoloader-lowest-long-files-hash"
 expect eof
 
+# Confirm environment variables.
 set fp [open $gitHubEnvFile r]
 set fileData [read $fp]
 close $fp
@@ -27,5 +32,19 @@ if { $expectedValue != $fileData } {
     exit 1
 }
 
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "key=Linux-php-8.1.1-composer---ignore-platform-reqs---optimize-autoloader-lowest-long-files-hash\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
 # Clean up
 file delete $gitHubEnvFile
+file delete $gitHubOutputFile
diff --git a/tests/expect/cache_key_05.exp b/tests/expect/cache_key_05.exp
index 242c4ff..0b6b27b 100755
--- a/tests/expect/cache_key_05.exp
+++ b/tests/expect/cache_key_05.exp
@@ -1,17 +1,22 @@
 #!/usr/bin/env -S expect -f
 
+# For testing environment variables written to GITHUB_ENV
 set gitHubEnvFile cache_key_05.txt
 set ::env(GITHUB_ENV) $gitHubEnvFile
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile cache_key_output_05.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/cache_key.sh "Linux" "8.1.1" "locked" "" "long-files-hash" "my-custom-key"
 match_max 100000
 
 expect -exact "::debug::Cache primary key is 'my-custom-key'"
 expect -exact "::debug::Cache restore keys are ''"
-expect -exact "::set-output name=key::my-custom-key"
 expect eof
 
+# Confirm environment variables.
 set fp [open $gitHubEnvFile r]
 set fileData [read $fp]
 close $fp
@@ -27,5 +32,19 @@ if { $expectedValue != $fileData } {
     exit 1
 }
 
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "key=my-custom-key\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
 # Clean up
 file delete $gitHubEnvFile
+file delete $gitHubOutputFile
diff --git a/tests/expect/cache_key_06.exp b/tests/expect/cache_key_06.exp
index 0706cfb..caeda76 100755
--- a/tests/expect/cache_key_06.exp
+++ b/tests/expect/cache_key_06.exp
@@ -1,17 +1,22 @@
 #!/usr/bin/env -S expect -f
 
+# For testing environment variables written to GITHUB_ENV
 set gitHubEnvFile cache_key_06.txt
 set ::env(GITHUB_ENV) $gitHubEnvFile
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile cache_key_output_06.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/cache_key.sh "Linux" "8.1.1" "" "" "long-files-hash" "" "path/to/working/dir"
 match_max 100000
 
 expect -exact "::debug::Cache primary key is 'Linux-php-8.1.1-composer-locked-path/to/working/dir-long-files-hash'"
 expect -exact "::debug::Cache restore keys are 'Linux-php-8.1.1-composer-locked-path/to/working/dir-'"
-expect -exact "::set-output name=key::Linux-php-8.1.1-composer-locked-path/to/working/dir-long-files-hash"
 expect eof
 
+# Confirm environment variables.
 set fp [open $gitHubEnvFile r]
 set fileData [read $fp]
 close $fp
@@ -27,5 +32,19 @@ if { $expectedValue != $fileData } {
     exit 1
 }
 
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "key=Linux-php-8.1.1-composer-locked-path/to/working/dir-long-files-hash\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
 # Clean up
 file delete $gitHubEnvFile
+file delete $gitHubOutputFile
diff --git a/tests/expect/cache_key_07.exp b/tests/expect/cache_key_07.exp
index 7721b3b..1153892 100755
--- a/tests/expect/cache_key_07.exp
+++ b/tests/expect/cache_key_07.exp
@@ -1,17 +1,22 @@
 #!/usr/bin/env -S expect -f
 
+# For testing environment variables written to GITHUB_ENV
 set gitHubEnvFile cache_key_07.txt
 set ::env(GITHUB_ENV) $gitHubEnvFile
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile cache_key_output_07.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/cache_key.sh "Windows" "8.0.2" "foobar" "" "some-other-hash"
 match_max 100000
 
 expect -exact "::debug::Cache primary key is 'Windows-php-8.0.2-composer-locked-some-other-hash'"
 expect -exact "::debug::Cache restore keys are 'Windows-php-8.0.2-composer-locked-'"
-expect -exact "::set-output name=key::Windows-php-8.0.2-composer-locked-some-other-hash"
 expect eof
 
+# Confirm environment variables.
 set fp [open $gitHubEnvFile r]
 set fileData [read $fp]
 close $fp
@@ -27,5 +32,19 @@ if { $expectedValue != $fileData } {
     exit 1
 }
 
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "key=Windows-php-8.0.2-composer-locked-some-other-hash\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
 # Clean up
 file delete $gitHubEnvFile
+file delete $gitHubOutputFile
diff --git a/tests/expect/composer_paths_01.exp b/tests/expect/composer_paths_01.exp
index 4d3f3a9..95c6dfd 100755
--- a/tests/expect/composer_paths_01.exp
+++ b/tests/expect/composer_paths_01.exp
@@ -1,5 +1,8 @@
 #!/usr/bin/env -S expect -f
 
+set gitHubOutputFile composer_paths_01.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/composer_paths.sh
 match_max 100000
@@ -9,9 +12,19 @@ expect "::debug::Composer path is '*'\r
 ::debug::Composer cache directory found at '*'\r
 ::debug::File composer.json found at './composer.json'\r
 ::debug::File composer.lock path computed as './composer.lock'\r
-::set-output name=command::*\r
-::set-output name=cache-dir::*\r
-::set-output name=json::./composer.json\r
-::set-output name=lock::./composer.lock\r
 "
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+if {[regexp {^composer_command=\S*\s*cache-dir=\S*\s*json=\./composer\.json\s*lock=./composer.lock\s*$} $fileData] == 0} {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/composer_paths_05.exp b/tests/expect/composer_paths_05.exp
index 5e81a89..676476b 100755
--- a/tests/expect/composer_paths_05.exp
+++ b/tests/expect/composer_paths_05.exp
@@ -1,5 +1,9 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile composer_paths_05.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/composer_paths.sh "" "../fixtures/no-lock-file"
 match_max 100000
@@ -10,9 +14,19 @@ expect "::debug::Unable to find composer.lock at '../fixtures/no-lock-file/compo
 ::debug::Composer cache directory found at '*'\r
 ::debug::File composer.json found at '../fixtures/no-lock-file/composer.json'\r
 ::debug::File composer.lock path computed as ''\r
-::set-output name=command::*\r
-::set-output name=cache-dir::*\r
-::set-output name=json::../fixtures/no-lock-file/composer.json\r
-::set-output name=lock::\r
 "
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+if {[regexp {^composer_command=\S*\s*cache-dir=\S*\s*json=\.\./fixtures/no-lock-file/composer\.json\s*lock=\s*$} $fileData] == 0} {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/composer_paths_06.exp b/tests/expect/composer_paths_06.exp
index a0d2da7..7b176ee 100755
--- a/tests/expect/composer_paths_06.exp
+++ b/tests/expect/composer_paths_06.exp
@@ -1,5 +1,9 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile composer_paths_06.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/composer_paths.sh "" "../fixtures/with-lock-file"
 match_max 100000
@@ -9,9 +13,19 @@ expect "::debug::Composer path is '*'\r
 ::debug::Composer cache directory found at '*'\r
 ::debug::File composer.json found at '../fixtures/with-lock-file/composer.json'\r
 ::debug::File composer.lock path computed as '../fixtures/with-lock-file/composer.lock'\r
-::set-output name=command::*\r
-::set-output name=cache-dir::*\r
-::set-output name=json::../fixtures/with-lock-file/composer.json\r
-::set-output name=lock::../fixtures/with-lock-file/composer.lock\r
 "
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+if {[regexp {^composer_command=\S*\s*cache-dir=\S*\s*json=\.\./fixtures/with-lock-file/composer\.json\s*lock=\.\./fixtures/with-lock-file/composer\.lock\s*$} $fileData] == 0} {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/composer_paths_08.exp b/tests/expect/composer_paths_08.exp
index 7e96005..01fb397 100755
--- a/tests/expect/composer_paths_08.exp
+++ b/tests/expect/composer_paths_08.exp
@@ -1,5 +1,9 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile composer_paths_08.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/composer_paths.sh "" "../fixtures/out-of-sync-lock"
 match_max 100000
@@ -9,9 +13,19 @@ expect "::debug::Composer path is '*'\r
 ::debug::Composer cache directory found at '*'\r
 ::debug::File composer.json found at '../fixtures/out-of-sync-lock/composer.json'\r
 ::debug::File composer.lock path computed as '../fixtures/out-of-sync-lock/composer.lock'\r
-::set-output name=command::*\r
-::set-output name=cache-dir::*\r
-::set-output name=json::../fixtures/out-of-sync-lock/composer.json\r
-::set-output name=lock::../fixtures/out-of-sync-lock/composer.lock\r
 "
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+if {[regexp {^composer_command=\S*\s*cache-dir=\S*\s*json=\.\./fixtures/out-of-sync-lock/composer\.json\s*lock=\.\./fixtures/out-of-sync-lock/composer\.lock\s*$} $fileData] == 0} {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/composer_paths_09.exp b/tests/expect/composer_paths_09.exp
index 953b5a0..8575903 100755
--- a/tests/expect/composer_paths_09.exp
+++ b/tests/expect/composer_paths_09.exp
@@ -1,17 +1,31 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile composer_paths_09.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/composer_paths.sh "../fixtures/composer.phar"
 match_max 100000
 
 expect "::debug::Composer path is '../fixtures/composer.phar'\r
-::debug::Composer version 2.2.2 2021-12-29 14:15:27\r
+::debug::Composer version 2.2.18 2022-08-20 11:33:38\r
 ::debug::Composer cache directory found at '*'\r
 ::debug::File composer.json found at './composer.json'\r
 ::debug::File composer.lock path computed as './composer.lock'\r
-::set-output name=command::../fixtures/composer.phar\r
-::set-output name=cache-dir::*\r
-::set-output name=json::./composer.json\r
-::set-output name=lock::./composer.lock\r
 "
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+if {[regexp {^composer_command=\.\./fixtures/composer\.phar\s*cache-dir=\S*\s*json=\./composer\.json\s*lock=\./composer\.lock\s*$} $fileData] == 0} {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/php_version_01.exp b/tests/expect/php_version_01.exp
index eae2c7a..68f80f3 100755
--- a/tests/expect/php_version_01.exp
+++ b/tests/expect/php_version_01.exp
@@ -1,12 +1,28 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile php_version_01.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/php_version.sh
 match_max 100000
 
 expect "::debug::PHP path is '*'\r
 ::debug::PHP version is '*.*.*'\r
-::set-output name=path::*\r
-::set-output name=version::*.*.*\r
 "
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+if {[regexp {^path=\S*\s*version=\d*\.\d*\.\d*\s*$} $fileData] == 0} {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/should_cache_01.exp b/tests/expect/should_cache_01.exp
index 82e8bc3..8cab46c 100755
--- a/tests/expect/should_cache_01.exp
+++ b/tests/expect/should_cache_01.exp
@@ -1,9 +1,28 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile should_cache_01.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/should_cache.sh
 match_max 100000
 
 expect -exact "::debug::We will cache the dependencies because ignore-cache is set to ''"
-expect -exact "::set-output name=do-cache::1"
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "do-cache=1\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/should_cache_02.exp b/tests/expect/should_cache_02.exp
index fb41936..91c04eb 100755
--- a/tests/expect/should_cache_02.exp
+++ b/tests/expect/should_cache_02.exp
@@ -1,9 +1,28 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile should_cache_02.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/should_cache.sh "no"
 match_max 100000
 
 expect -exact "::debug::We will cache the dependencies because ignore-cache is set to 'no'"
-expect -exact "::set-output name=do-cache::1"
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "do-cache=1\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/should_cache_03.exp b/tests/expect/should_cache_03.exp
index 160401b..e86a442 100755
--- a/tests/expect/should_cache_03.exp
+++ b/tests/expect/should_cache_03.exp
@@ -1,9 +1,28 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile should_cache_03.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/should_cache.sh "yes"
 match_max 100000
 
 expect -exact "::debug::We will NOT cache the dependencies because ignore-cache is set to 'yes'"
-expect -exact "::set-output name=do-cache::0"
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "do-cache=0\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/should_cache_04.exp b/tests/expect/should_cache_04.exp
index 098c4c4..e52973c 100755
--- a/tests/expect/should_cache_04.exp
+++ b/tests/expect/should_cache_04.exp
@@ -1,9 +1,28 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile should_cache_04.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/should_cache.sh "true"
 match_max 100000
 
 expect -exact "::debug::We will NOT cache the dependencies because ignore-cache is set to 'true'"
-expect -exact "::set-output name=do-cache::0"
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "do-cache=0\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/should_cache_05.exp b/tests/expect/should_cache_05.exp
index b26f3e0..15a46ff 100755
--- a/tests/expect/should_cache_05.exp
+++ b/tests/expect/should_cache_05.exp
@@ -1,9 +1,28 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile should_cache_05.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/should_cache.sh "1"
 match_max 100000
 
 expect -exact "::debug::We will NOT cache the dependencies because ignore-cache is set to '1'"
-expect -exact "::set-output name=do-cache::0"
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "do-cache=0\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/should_cache_06.exp b/tests/expect/should_cache_06.exp
index b767c5e..b2c951a 100755
--- a/tests/expect/should_cache_06.exp
+++ b/tests/expect/should_cache_06.exp
@@ -1,9 +1,28 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile should_cache_06.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/should_cache.sh "false"
 match_max 100000
 
 expect -exact "::debug::We will cache the dependencies because ignore-cache is set to 'false'"
-expect -exact "::set-output name=do-cache::1"
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "do-cache=1\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/should_cache_07.exp b/tests/expect/should_cache_07.exp
index dbb1369..ca239ca 100755
--- a/tests/expect/should_cache_07.exp
+++ b/tests/expect/should_cache_07.exp
@@ -1,9 +1,28 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile should_cache_07.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/should_cache.sh "0"
 match_max 100000
 
 expect -exact "::debug::We will cache the dependencies because ignore-cache is set to '0'"
-expect -exact "::set-output name=do-cache::1"
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "do-cache=1\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile
diff --git a/tests/expect/should_cache_08.exp b/tests/expect/should_cache_08.exp
index 4032458..cf3f460 100755
--- a/tests/expect/should_cache_08.exp
+++ b/tests/expect/should_cache_08.exp
@@ -1,9 +1,28 @@
 #!/usr/bin/env -S expect -f
 
+# For testing outputs variables written to GITHUB_OUTPUT
+set gitHubOutputFile should_cache_08.txt
+set ::env(GITHUB_OUTPUT) $gitHubOutputFile
+
 set timeout 3
 spawn ../../bin/should_cache.sh "foo"
 match_max 100000
 
 expect -exact "::debug::We will cache the dependencies because ignore-cache is set to 'foo'"
-expect -exact "::set-output name=do-cache::1"
 expect eof
+
+# Verify output variables have been set correctly.
+set fp [open $gitHubOutputFile r]
+set fileData [read $fp]
+close $fp
+
+set expectedValue "do-cache=1\n"
+
+if { $expectedValue != $fileData } {
+    puts "\nExpected output variable does not match. Received:\n"
+    puts $fileData
+    exit 1
+}
+
+# Clean up
+file delete $gitHubOutputFile