2 files changed, 90 insertions, 0 deletions
diff --git a/Tests/Environment/CMakeLists.txt b/Tests/Environment/CMakeLists.txt
index 2b18d24..17009bd 100644
--- a/Tests/Environment/CMakeLists.txt
+++ b/Tests/Environment/CMakeLists.txt
@@ -9,6 +9,7 @@ add_test(Environment1 Environment)
 add_test(Environment2 Environment)
 add_test(EchoEnvironment1 ${CMAKE_COMMAND} -E environment)
 add_test(EchoEnvironment2 ${CMAKE_COMMAND} -E environment)
+add_test(EchoEnvironment3 ${CMAKE_COMMAND} -P "${CMAKE_CURRENT_SOURCE_DIR}/check_mod.cmake")
 
 # Make sure "CMAKE_ENV.*Happy Thanksgiving" is in the output of
 # the "1" tests:
@@ -24,3 +25,37 @@ set_tests_properties(Environment1 EchoEnvironment1 PROPERTIES
 set_tests_properties(Environment2 EchoEnvironment2 PROPERTIES
   FAIL_REGULAR_EXPRESSION "CMAKE_ENV.*Happy Thanksgiving"
 )
+
+set_property(TEST EchoEnvironment3
+  PROPERTY ENVIRONMENT_MODIFICATION
+    # Variables expected to be unset.
+    "UNSET_EXPLICIT=set:value"
+    "UNSET_EXPLICIT=unset:"
+    "UNSET_VIA_RESET=set:value"
+    "UNSET_VIA_RESET=reset:"
+
+    # Direct settings.
+    "DIRECT=set:old"
+    "DIRECT=set:new"
+
+    # String manipulation.
+    "STRING_MANIP=set:-core-"
+    "STRING_MANIP=string_append:post-"
+    "STRING_MANIP=string_prepend:-pre"
+    "STRING_MANIP=string_append:suffix"
+    "STRING_MANIP=string_prepend:prefix"
+
+    # Path manipulation.
+    "PATH_MANIP=set:core"
+    "PATH_MANIP=path_list_append:post"
+    "PATH_MANIP=path_list_prepend:pre"
+    "PATH_MANIP=path_list_append:suffix"
+    "PATH_MANIP=path_list_prepend:prefix"
+
+    # CMake list manipulation.
+    "CMAKE_LIST_MANIP=set:core"
+    "CMAKE_LIST_MANIP=cmake_list_append:post"
+    "CMAKE_LIST_MANIP=cmake_list_prepend:pre"
+    "CMAKE_LIST_MANIP=cmake_list_append:suffix"
+    "CMAKE_LIST_MANIP=cmake_list_prepend:prefix"
+)
diff --git a/Tests/Environment/check_mod.cmake b/Tests/Environment/check_mod.cmake
new file mode 100644
index 0000000..16d02f2
--- /dev/null
+++ b/Tests/Environment/check_mod.cmake
@@ -0,0 +1,55 @@
+execute_process(
+  COMMAND ${CMAKE_COMMAND} -E environment
+  OUTPUT_VARIABLE out
+  ERROR_VARIABLE err
+  RESULT_VARIABLE res)
+
+if (res)
+  message(FATAL_ERROR "Failed with exit code ${res}: ${err}")
+endif ()
+
+if (CMAKE_HOST_WIN32)
+  set(path_sep ";")
+else ()
+  set(path_sep ":")
+endif ()
+
+set(unexpect_UNSET_EXPLICIT "")
+set(unexpect_UNSET_VIA_RESET "")
+set(expect_DIRECT "new")
+set(expect_STRING_MANIP "prefix-pre-core-post-suffix")
+set(expect_PATH_MANIP "prefix${path_sep}pre${path_sep}core${path_sep}post${path_sep}suffix")
+set(expect_CMAKE_LIST_MANIP "prefix;pre;core;post;suffix")
+
+set(expected_vars
+  DIRECT
+  STRING_MANIP
+  PATH_MANIP
+  CMAKE_LIST_MANIP)
+
+while (out)
+  string(FIND "${out}" "\n" nl_pos)
+  string(SUBSTRING "${out}" 0 "${nl_pos}" line)
+  math(EXPR line_next "${nl_pos} + 1")
+  string(SUBSTRING "${out}" "${line_next}" -1 out)
+
+  string(FIND "${line}" "=" eq_pos)
+  string(SUBSTRING "${line}" 0 "${eq_pos}" name)
+  math(EXPR value_start "${eq_pos} + 1")
+  string(SUBSTRING "${line}" "${value_start}" -1 value)
+
+  if (DEFINED "unexpect_${name}")
+    message(SEND_ERROR "Found `${name}=${value}` when it should have been unset")
+  elseif (DEFINED "expect_${name}")
+    list(REMOVE_ITEM expected_vars "${name}")
+    if (expect_${name} STREQUAL value)
+      message(STATUS "Found `${name}=${value}` as expected")
+    else ()
+      message(SEND_ERROR "Found `${name}=${value}` when it should have been ${expect_${name}}")
+    endif ()
+  endif ()
+endwhile ()
+
+if (expected_vars)
+  message(SEND_ERROR "Did not test expected variables: ${expected_vars}")
+endif ()