diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8d89f7a9..afbd1875 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 - `--list` (alias `--dry-run`) prints the tests a run would execute, without running them; `--list-format json` emits file, function, name, line and tags. Honours every selection flag, including `--shard` and `--random-order --seed` ordering (#1007)
 - `# @tags a b` above any top-level line applies those tags to every test in the file, unioned with per-function `# @tag` (#1008)
 - `--tag` accepts expressions: `'a&&b'` (AND) and `'!a'` (NOT), combinable as `'a&&!b'`. Repeated `--tag` flags keep OR semantics, and `--exclude-tag` still wins (#1008)
+- `assert_command_available <command>` asserts that an external command, shell builtin or function resolves through `command -v` (#1027)
 - The coverage engine in use is reported by `--verbose`, and an explicit `BASHUNIT_COVERAGE_ENGINE=xtrace` that the running Bash cannot honour now warns instead of being silently ignored (#1005)
 
 ### Changed
diff --git a/README.md b/README.md
index e46dc2df..78f8754b 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@
 ## Why bashunit
 
 A lightweight, fast testing framework for **Bash 3.0+**, focused on developer experience.
-It ships 73 assertions plus spies, mocks, data providers, snapshots and more.
+It ships 75 assertions plus spies, mocks, data providers, snapshots and more.
 
 ## Quick start
 
diff --git a/completions/_bashunit b/completions/_bashunit
index 8202c39f..62724ebf 100644
--- a/completions/_bashunit
+++ b/completions/_bashunit
@@ -17,7 +17,7 @@ _bashunit() {
     assert_fns=(
       assert_array_contains assert_array_length assert_array_not_contains
       assert_arrays_equal assert_assertion_fails assert_assertion_fails_with
-      assert_assertion_passes assert_command_not_found assert_contains
+      assert_assertion_passes assert_command_available assert_command_not_found assert_contains
       assert_contains_ignore_case assert_date_after assert_date_before
       assert_date_equals assert_date_within_delta assert_date_within_range
       assert_directory_exists assert_directory_not_exists assert_duration
diff --git a/completions/bashunit.bash b/completions/bashunit.bash
index 2836bb4f..0f2aa29b 100644
--- a/completions/bashunit.bash
+++ b/completions/bashunit.bash
@@ -30,7 +30,7 @@ _BASHUNIT_COMPLETIONS_TEST_OPTS="--assert --boot --coverage --coverage-exclude \
 
 _BASHUNIT_COMPLETIONS_ASSERT_FNS="assert_array_contains assert_array_length \
 assert_array_not_contains assert_arrays_equal assert_assertion_fails \
-assert_assertion_fails_with assert_assertion_passes assert_command_not_found \
+assert_assertion_fails_with assert_assertion_passes assert_command_available assert_command_not_found \
 assert_contains assert_contains_ignore_case assert_date_after \
 assert_date_before assert_date_equals assert_date_within_delta \
 assert_date_within_range assert_directory_exists assert_directory_not_exists \
diff --git a/docs/assertions.md b/docs/assertions.md
index de9c15f2..19d0bba0 100644
--- a/docs/assertions.md
+++ b/docs/assertions.md
@@ -22,7 +22,7 @@ to narrow it (`bashunit doc json`).
 | **Strings** | [assert_contains](#assert-contains) · [assert_not_contains](#assert-not-contains) · [assert_contains_ignore_case](#assert-contains-ignore-case) · [assert_matches](#assert-matches) · [assert_not_matches](#assert-not-matches) · [assert_string_starts_with](#assert-string-starts-with) · [assert_string_not_starts_with](#assert-string-not-starts-with) · [assert_string_ends_with](#assert-string-ends-with) · [assert_string_not_ends_with](#assert-string-not-ends-with) · [assert_string_matches_format](#assert-string-matches-format) · [assert_string_not_matches_format](#assert-string-not-matches-format) · [assert_empty](#assert-empty) · [assert_not_empty](#assert-not-empty) · [assert_line_count](#assert-line-count) |
 | **Numbers** | [assert_less_than](#assert-less-than) · [assert_less_or_equal_than](#assert-less-or-equal-than) · [assert_greater_than](#assert-greater-than) · [assert_greater_or_equal_than](#assert-greater-or-equal-than) · [assert_within_delta](#assert-within-delta) |
 | **Dates** | [assert_date_equals](#assert-date-equals) · [assert_date_before](#assert-date-before) · [assert_date_after](#assert-date-after) · [assert_date_within_range](#assert-date-within-range) · [assert_date_within_delta](#assert-date-within-delta) |
-| **Exit codes and commands** | [assert_exit_code](#assert-exit-code) · [assert_successful_code](#assert-successful-code) · [assert_unsuccessful_code](#assert-unsuccessful-code) · [assert_general_error](#assert-general-error) · [assert_command_not_found](#assert-command-not-found) · [assert_exec](#assert-exec) |
+| **Exit codes and commands** | [assert_exit_code](#assert-exit-code) · [assert_successful_code](#assert-successful-code) · [assert_unsuccessful_code](#assert-unsuccessful-code) · [assert_general_error](#assert-general-error) · [assert_command_available](#assert-command-available) · [assert_command_not_found](#assert-command-not-found) · [assert_exec](#assert-exec) |
 | **Files** | [assert_file_exists](#assert-file-exists) · [assert_file_not_exists](#assert-file-not-exists) · [assert_file_contains](#assert-file-contains) · [assert_file_not_contains](#assert-file-not-contains) · [assert_is_file](#assert-is-file) · [assert_is_file_empty](#assert-is-file-empty) · [assert_is_symlink](#assert-is-symlink) · [assert_is_not_symlink](#assert-is-not-symlink) · [assert_symlink_to](#assert-symlink-to) · [assert_file_permissions](#assert-file-permissions) · [assert_files_equals](#assert-files-equals) · [assert_files_not_equals](#assert-files-not-equals) |
 | **Directories** | [assert_directory_exists](#assert-directory-exists) · [assert_directory_not_exists](#assert-directory-not-exists) · [assert_is_directory](#assert-is-directory) · [assert_is_directory_empty](#assert-is-directory-empty) · [assert_is_directory_not_empty](#assert-is-directory-not-empty) · [assert_is_directory_readable](#assert-is-directory-readable) · [assert_is_directory_not_readable](#assert-is-directory-not-readable) · [assert_is_directory_writable](#assert-is-directory-writable) · [assert_is_directory_not_writable](#assert-is-directory-not-writable) |
 | **Arrays** | [assert_arrays_equal](#assert-arrays-equal) · [assert_array_contains](#assert-array-contains) · [assert_array_not_contains](#assert-array-not-contains) · [assert_array_length](#assert-array-length) |
@@ -832,6 +832,33 @@ function test_failure() {
 ```
 :::
 
+## assert_command_available
+> `assert_command_available "command"`
+
+Reports an error if `command` is not available.
+
+Availability uses the same `command -v` check as the
+[bashunit::is_command_available](/globals#bashunit-is-command-available) helper, so
+external commands, shell builtins and shell functions are supported. The command
+is only resolved; it is not executed.
+
+::: code-group
+```bash [Example]
+function test_dependencies_are_installed() {
+  assert_command_available bash
+  assert_command_available jq
+}
+
+function test_shell_function_is_available() {
+  function project_build() {
+    make build
+  }
+
+  assert_command_available project_build
+}
+```
+:::
+
 ## assert_command_not_found
 > `assert_command_not_found`
 
diff --git a/docs/public/bashunit-skill.md b/docs/public/bashunit-skill.md
index 82dbcc8b..7f08f7cc 100644
--- a/docs/public/bashunit-skill.md
+++ b/docs/public/bashunit-skill.md
@@ -118,7 +118,7 @@ cleaned up automatically and are safe under `--parallel`.
 
 ## Assertions
 
-`bashunit doc` prints the full catalogue (73 assertions) locally; `bashunit doc contains`
+`bashunit doc` prints the full catalogue (75 assertions) locally; `bashunit doc contains`
 filters it. The same list is at https://bashunit.com/assertions. **Do not invent names**
 — a wrong name is a runtime error, not a failed assertion.
 
@@ -127,7 +127,7 @@ filters it. The same list is at https://bashunit.com/assertions. **Do not invent
   `assert_string_starts_with`, `assert_string_ends_with`, `assert_empty`, `assert_not_empty`
 - Numbers: `assert_greater_than`, `assert_less_than`, `assert_within_delta`
 - Exit codes: `assert_successful_code`, `assert_general_error`, `assert_exit_code`,
-  `assert_command_not_found`
+  `assert_command_not_found`, `assert_command_available`
 - Files: `assert_file_exists`, `assert_file_contains`, `assert_is_file_empty`,
   `assert_directory_exists`, `assert_file_permissions`
 - Arrays: `assert_array_contains`, `assert_array_length`, `assert_arrays_equal`
diff --git a/src/assert/core.sh b/src/assert/core.sh
index c03a287b..e0954866 100755
--- a/src/assert/core.sh
+++ b/src/assert/core.sh
@@ -814,6 +814,32 @@ function assert_general_error() {
   bashunit::state::add_assertions_passed
 }
 
+##
+# Reports an error unless the command resolves through
+# bashunit::is_command_available, so builtins and shell functions count as
+# available exactly as they do for that helper. The command is resolved, never
+# executed.
+# Arguments: $1 - command, $2 - label override (optional)
+##
+function assert_command_available() {
+  bashunit::assert::should_skip && return 0
+  if [ "$#" -lt 1 ]; then
+    bashunit::assert::usage_error "${FUNCNAME[0]}" 1 "command" "$#"
+    return 2
+  fi
+
+  local command="$1"
+  local label_override="${2:-}"
+
+  if ! bashunit::is_command_available "$command"; then
+    bashunit::assert::fail_with "${label_override:-}" \
+      "${command}" "to be available but was" "not found"
+    return
+  fi
+
+  bashunit::state::add_assertions_passed
+}
+
 function assert_command_not_found() {
   local actual_exit_code=${3-"$?"} # Capture $? before guard check
   local label_override=""
diff --git a/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_all_assert_docs.snapshot b/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_all_assert_docs.snapshot
index 3d150e4f..eaa54f5f 100644
--- a/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_all_assert_docs.snapshot
+++ b/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_all_assert_docs.snapshot
@@ -319,6 +319,18 @@ Use assert_exec if you want to pass a command as a string and check its exit cod
 - assert_exit_code is the full version of this assertion where you can specify the expected exit code.
 
 
+## assert_command_available
+--------------
+> `assert_command_available "command"`
+
+Reports an error if `command` is not available.
+
+Availability uses the same `command -v` check as the
+bashunit::is_command_available(/globals#bashunit-is-command-available) helper, so
+external commands, shell builtins and shell functions are supported. The command
+is only resolved; it is not executed.
+
+
 ## assert_command_not_found
 --------------
 > `assert_command_not_found`
diff --git a/tests/unit/assert/advanced_test.sh b/tests/unit/assert/advanced_test.sh
index fc29dd07..0660f9fb 100644
--- a/tests/unit/assert/advanced_test.sh
+++ b/tests/unit/assert/advanced_test.sh
@@ -55,6 +55,57 @@ function test_unsuccessful_assert_command_not_found() {
     "$(assert_command_not_found "$(fake_function)")"
 }
 
+function test_successful_assert_command_available_for_external_command() {
+  assert_empty "$(assert_command_available bash)"
+}
+
+function test_successful_assert_command_available_for_builtin() {
+  assert_empty "$(assert_command_available printf)"
+}
+
+function test_successful_assert_command_available_for_shell_function() {
+  function available_shell_function() {
+    # shellcheck disable=SC2317  # Never invoked: the assertion only resolves it.
+    :
+  }
+
+  assert_empty "$(assert_command_available available_shell_function)"
+}
+
+function test_unsuccessful_assert_command_available_names_command() {
+  local command_name="bashunit_command_that_does_not_exist"
+
+  assert_same \
+    "$(bashunit::console_results::print_failed_test \
+      "Unsuccessful assert command available names command" \
+      "$command_name" "to be available but was" "not found")" \
+    "$(assert_command_available "$command_name")"
+}
+
+function test_unsuccessful_assert_command_available_with_custom_label() {
+  assert_same \
+    "$(bashunit::console_results::print_failed_test "my custom label" \
+      "bashunit_command_that_does_not_exist" "to be available but was" "not found")" \
+    "$(assert_command_available "bashunit_command_that_does_not_exist" "my custom label")"
+}
+
+function test_assert_command_available_moves_the_assertion_counters() {
+  assert_assertion_passes assert_command_available printf
+  assert_assertion_fails assert_command_available "bashunit_command_that_does_not_exist"
+}
+
+# The two never agree about the same command. Both run inside $() so their
+# failures stay in the subshell instead of moving this test's counters.
+function test_assert_command_available_is_the_inverse_of_assert_command_not_found() {
+  # Missing: not_found passes on the 127, available fails.
+  assert_empty "$(assert_command_not_found "$(bashunit_command_that_does_not_exist 2>/dev/null)")"
+  assert_not_empty "$(assert_command_available "bashunit_command_that_does_not_exist")"
+
+  # Present: available passes, not_found fails on the 0.
+  assert_empty "$(assert_command_available printf)"
+  assert_not_empty "$(assert_command_not_found "$(printf '')")"
+}
+
 function test_successful_assert_exec() {
   # shellcheck disable=SC2317
   function fake_command() {
diff --git a/tests/unit/assert/arity_test.sh b/tests/unit/assert/arity_test.sh
index 285f087c..21aa71b1 100644
--- a/tests/unit/assert/arity_test.sh
+++ b/tests/unit/assert/arity_test.sh
@@ -1,17 +1,23 @@
 #!/usr/bin/env bash
 
-# @data_provider provide_core_comparison_assertions
-function test_core_comparison_assertions_reject_missing_arguments() {
+# @data_provider provide_core_assertions_requiring_arguments
+function test_core_assertions_reject_missing_arguments() {
   local assertion=$1
   local required=$2
   local signature=$3
   local output exit_code=0
 
-  if [ "$required" -eq 3 ]; then
-    output=$("$assertion" "first" "second" 2>&1) || exit_code=$?
-  else
-    output=$("$assertion" "first" 2>&1) || exit_code=$?
-  fi
+  # One argument short of the signature, whatever the arity. The `+` guard keeps
+  # an empty list expandable under `set -u` on Bash 3.x (a one-argument
+  # assertion is called with nothing at all).
+  local supplied=1
+  local -a args=()
+  while [ "$supplied" -lt "$required" ]; do
+    args[${#args[@]}]="arg${supplied}"
+    supplied=$((supplied + 1))
+  done
+
+  output=$("$assertion" "${args[@]+"${args[@]}"}" 2>&1) || exit_code=$?
 
   assert_same 2 "$exit_code"
   assert_same \
@@ -19,7 +25,7 @@ function test_core_comparison_assertions_reject_missing_arguments() {
     "$output"
 }
 
-function provide_core_comparison_assertions() {
+function provide_core_assertions_requiring_arguments() {
   bashunit::data_set assert_same 2 "expected, actual"
   bashunit::data_set assert_equals 2 "expected, actual"
   bashunit::data_set assert_not_same 2 "expected, actual"
@@ -41,6 +47,7 @@ function provide_core_comparison_assertions() {
   bashunit::data_set assert_line_count 2 "expected, actual"
   bashunit::data_set assert_string_matches_format 2 "format, actual"
   bashunit::data_set assert_string_not_matches_format 2 "format, actual"
+  bashunit::data_set assert_command_available 1 "command"
 }
 
 function test_empty_values_still_count_as_supplied_arguments() {