Fix test framework and add input type check tests

This commit's tests do not run through properly, I will fix that in the next few commits.

test.sh

@@ -1,8 +1,9 @@
 #!/usr/bin/env bash
+export "LC_ALL=C.UTF-8"
 set -uo pipefail
 IFS=$'\n'
 
-unset TEST TESTS
+unset TESTS TEST STAGE
 
 TESTS="
 # Logging
@@ -15,34 +16,38 @@ logger_error
 logger_crash
 
 # Checks
+## Command type
 check_command_alias
 check_command_keyword
 check_command_function
 check_command_builtin
 check_command_file
 check_command_defined
+## Input type
+check_input_bool
+check_input_byte
+check_input_int
+check_input_char
 "
 
 # Utility methods
 function invalid() { echo ":: Error: Invalid test ${TEST}, skipping"; }
 function fail() {
-  echo -e ":: Test ${TEST} failed\n   ${*//\\n/\\n   }"
+  echo -e ":: Test ${TEST} failed during stage ${STAGE}\n   ${*//\\n/\\n   }"
-  [ "${TEST_FAILFAST}" == "true" ] && exit 1
+  [ "${TEST_FAILFAST:-true}" == "true" ] && exit 1
 }
 ## Assertions
 function assert_equals() {
   EXPECTED="${1}"
-  shift
+  ACTUAL="${2}"
-  ACTUAL="${*}"
 
-  [[ "${ACTUAL}" != "${EXPECTED}" ]] && fail "${1}" "String does not match expected string\nExpected: ${EXPECTED}\nActual: ${ACTUAL}"
+  [[ "${ACTUAL}" != "${EXPECTED}" ]] && fail "String does not match expected string\nExpected: '${EXPECTED}'\nActual: '${ACTUAL}'"
 }
 function assert_contains() {
   EXPECTED="${1}"
-   shift
+  ACTUAL="${2}"
-   ACTUAL="${*}"
 
-   [[ "${ACTUAL}" != *"${EXPECTED}"* ]] && fail "${1}" "String does not contain expected string\nExpected: ${EXPECTED}\nActual: ${ACTUAL}"
+  [[ "${ACTUAL}" != *"${EXPECTED}"* ]] && fail "String does not contain expected string\nExpected: '${EXPECTED}'\nActual: '${ACTUAL}'"
  }
 
 # Test loop
@@ -50,7 +55,8 @@ for TEST in ${TESTS}; do
   [ -z "${TEST}" ] || [[ "${TEST}" == "#"* ]] && continue
 
   echo ":: Running test ${TEST}"
-  export TEST
+  export "TEST"
+  export "STAGE=0"
 
   # Logging
   if [[ "${TEST}" == "logger_"* ]]; then
@@ -73,7 +79,7 @@ for TEST in ${TESTS}; do
   elif [[ "${TEST}" == "check_"* ]]; then
     # Command checks
     if [[ "${TEST}" == "check_command_"* ]]; then
-      case "${TEST//check_command/}" in
+      case "${TEST//check_command_/}" in
         "alias")
           assert_equals "0" "$(
             source "bashutils.sh"
@@ -117,6 +123,123 @@ for TEST in ${TESTS}; do
             echo "${?}"
           )"
           ;;
+        *)
+          invalid
+          ;;
+      esac
+
+    # Input checks
+    elif [[ "${TEST}" == "check_input_"* ]]; then
+      case "${TEST//check_input_/}" in
+        "bool")
+          assert_equals "0" "$(
+            source "bashutils.sh"
+            is_input_bool "true"
+            echo "${?}"
+          )"
+          export "STAGE=1"
+          assert_equals "0" "$(
+            source "bashutils.sh"
+            is_input_bool "false"
+            echo "${?}"
+          )"
+          export "STAGE=2"
+          assert_equals "1" "$(
+            source "bashutils.sh"
+            is_input_bool "0"
+            echo "${?}"
+          )"
+          export "STAGE=3"
+          assert_equals "1" "$(
+            source "bashutils.sh"
+            is_input_bool "1"
+            echo "${?}"
+          )"
+          ;;
+        "byte")
+          assert_equals "0" "$(
+            source "bashutils.sh"
+            is_input_byte "0"
+            echo "${?}"
+          )"
+          export "STAGE=1"
+          assert_equals "0" "$(
+            source "bashutils.sh"
+            is_input_byte "255"
+            echo "${?}"
+          )"
+          export "STAGE=2"
+          assert_equals "0" "$(
+            source "bashutils.sh"
+            is_input_byte "69"
+            echo "${?}"
+          )"
+          export "STAGE=3"
+          assert_equals "1" "$(
+            source "bashutils.sh"
+            is_input_byte "256"
+            echo "${?}"
+          )"
+          export "STAGE=4"
+          assert_equals "1" "$(
+            source "bashutils.sh"
+            is_input_byte "-1"
+            echo "${?}"
+          )"
+          export "STAGE=5"
+          assert_equals "1" "$(
+            source "bashutils.sh"
+            is_input_int "asd"
+            echo "${?}"
+          )"
+          ;;
+        "int")
+          assert_equals "0" "$(
+            source "bashutils.sh"
+            is_input_int "9223372036854775807"
+            echo "${?}"
+          )"
+          export "STAGE=1"
+          assert_equals "1" "$(
+            source "bashutils.sh"
+            is_input_int "asd"
+            echo "${?}"
+          )"
+          ;;
+        "char")
+          assert_equals "0" "$(
+            source "bashutils.sh"
+            is_input_int "!"
+            echo "${?}"
+          )"
+          export "STAGE=1"
+          assert_equals "0" "$(
+            source "bashutils.sh"
+            is_input_int "™"
+            echo "${?}"
+          )"
+          export "STAGE=2"
+          assert_equals "0" "$(
+            source "bashutils.sh"
+            is_input_int "5"
+            echo "${?}"
+          )"
+          export "STAGE=3"
+          assert_equals "1" "$(
+            source "bashutils.sh"
+            is_input_int "asd"
+            echo "${?}"
+          )"
+          export "STAGE=4"
+          assert_equals "1" "$(
+            source "bashutils.sh"
+            is_input_int "666"
+            echo "${?}"
+          )"
+          ;;
+        *)
+          invalid
+          ;;
       esac
 
     # Invalid command