3 files changed, 142 insertions, 0 deletions
diff --git a/test/.clang-tidy b/test/.clang-tidy
index f869db0..401b1b0 100644
--- a/test/.clang-tidy
+++ b/test/.clang-tidy
@@ -9,6 +9,7 @@ Checks: >
   -bugprone-multi-level-implicit-pointer-conversion,
   -cert-err33-c,
   -clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling,
+  -concurrency-mt-unsafe,
   -cppcoreguidelines-avoid-non-const-global-variables,
   -google-readability-casting,
   -llvm-header-guard,
diff --git a/test/meson.build b/test/meson.build
index 6aa4e95..309551f 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -73,6 +73,7 @@ sequential_tests = {
   },
   'filesystem': {'': files('../README.md')},
   'digest': {'': []},
+  'environment': {'': []},
   'hash': {'': []},
   'path': {'': []},
   'status': {'': []},
diff --git a/test/test_environment.c b/test/test_environment.c
new file mode 100644
index 0000000..dba7b90
--- /dev/null
+++ b/test/test_environment.c
@@ -0,0 +1,140 @@
+// Copyright 2012-2024 David Robillard <d@drobilla.net>
+// SPDX-License-Identifier: ISC
+
+#undef NDEBUG
+
+#include "failing_allocator.h"
+
+#include <zix/allocator.h>
+#include <zix/environment.h>
+#include <zix/path.h>
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef _WIN32
+
+#  define HOME_NAME "USERPROFILE"
+#  define HOME_VAR "%USERPROFILE%"
+
+#else
+
+#  define HOME_NAME "HOME"
+#  define HOME_VAR "$HOME"
+
+static char*
+concat(ZixAllocator* const allocator,
+       const char* const   prefix,
+       const char* const   suffix)
+{
+  const size_t prefix_len = strlen(prefix);
+  const size_t suffix_len = strlen(suffix);
+  const size_t result_len = prefix_len + suffix_len;
+
+  char* const result = (char*)zix_calloc(allocator, 1U, result_len + 1U);
+  assert(result);
+  memcpy(result, prefix, prefix_len + 1U);
+  memcpy(result + prefix_len, suffix, suffix_len + 1U);
+  return result;
+}
+
+#endif
+
+static void
+check_expansion(const char* const path, const char* const expected)
+{
+  char* const expanded = zix_expand_environment_strings(NULL, path);
+  assert(expanded);
+  assert(!strcmp(expanded, expected));
+  zix_free(NULL, expanded);
+}
+
+static void
+test_expansion(void)
+{
+  // Check non-expansion of hopefully unset variables
+  check_expansion("$ZIX_UNSET0", "$ZIX_UNSET0");
+  check_expansion("$ZIX_unset0", "$ZIX_unset0");
+  check_expansion("%ZIX_UNSET0%", "%ZIX_UNSET0%");
+  check_expansion("%ZIX_unset0%", "%ZIX_unset0%");
+
+  // Check non-expansion of invalid variable names
+  check_expansion("$%INVALID", "$%INVALID");
+  check_expansion("$<INVALID>", "$<INVALID>");
+  check_expansion("$[INVALID]", "$[INVALID]");
+  check_expansion("$invalid", "$invalid");
+  check_expansion("${INVALID}", "${INVALID}");
+
+  const char* const home = getenv(HOME_NAME);
+  if (home) {
+    char* const var_foo  = zix_path_join(NULL, HOME_VAR, "foo");
+    char* const home_foo = zix_path_join(NULL, home, "foo");
+
+    check_expansion(var_foo, home_foo);
+
+#ifndef _WIN32
+    char* const tilde_foo      = zix_path_join(NULL, "~", "foo");
+    char* const home_and_other = concat(NULL, home, ":/other");
+    char* const other_and_home = concat(NULL, "/other:", home);
+    check_expansion("~other", "~other");
+    check_expansion("~", home);
+    check_expansion("~/foo", home_foo);
+    check_expansion("~:/other", home_and_other);
+    check_expansion("/other:~", other_and_home);
+    check_expansion("$HO", "$HO");
+    check_expansion("$HOMEZIX", "$HOMEZIX");
+    zix_free(NULL, other_and_home);
+    zix_free(NULL, home_and_other);
+    zix_free(NULL, tilde_foo);
+#endif
+
+    zix_free(NULL, home_foo);
+    zix_free(NULL, var_foo);
+  }
+}
+
+static void
+test_failed_alloc(void)
+{
+  ZixFailingAllocator allocator = zix_failing_allocator();
+
+  zix_failing_allocator_reset(&allocator, 0U);
+  assert(!zix_expand_environment_strings(&allocator.base, "/one:~"));
+  assert(!zix_expand_environment_strings(&allocator.base, "/only"));
+  assert(!zix_expand_environment_strings(&allocator.base, "~"));
+
+#ifndef _WIN32
+  zix_failing_allocator_reset(&allocator, 1U);
+  assert(!zix_expand_environment_strings(&allocator.base, "/one:~"));
+  assert(!zix_expand_environment_strings(&allocator.base, "/one:$HOME/two"));
+
+  zix_failing_allocator_reset(&allocator, 2U);
+  assert(!zix_expand_environment_strings(&allocator.base, "/one:$HOME/two"));
+#endif
+}
+
+#ifndef _WIN32
+
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+extern char** environ;
+
+static void
+test_null_environ(void)
+{
+  environ = NULL;
+  check_expansion(HOME_VAR, HOME_VAR);
+}
+
+#endif
+
+int
+main(void)
+{
+  test_expansion();
+  test_failed_alloc();
+#ifndef _WIN32
+  test_null_environ();
+#endif
+  return 0;
+}