feat: add support to format path writability assertion errors (#181)

cmake/Assertion.cmake

@@ -137,6 +137,9 @@ function(assert)
       elseif(ARGV0 STREQUAL "IS_READABLE")
         fail("expected path" ARGV1 "to be readable")
         return()
+      elseif(ARGV0 STREQUAL "IS_WRITABLE")
+        fail("expected path" ARGV1 "to be writable")
+        return()
       elseif(ARGV0 STREQUAL "IS_EXECUTABLE")
         fail("expected path" ARGV1 "to be an executable")
         return()
@@ -168,6 +171,9 @@ function(assert)
       elseif(ARGV1 STREQUAL "IS_READABLE")
         fail("expected path" ARGV2 "not to be readable")
         return()
+      elseif(ARGV1 STREQUAL "IS_WRITABLE")
+        fail("expected path" ARGV2 "not to be writable")
+        return()
       elseif(ARGV1 STREQUAL "IS_EXECUTABLE")
         fail("expected path" ARGV2 "not to be an executable")
         return()

test/assert.cmake

@@ -249,8 +249,7 @@ section("path readability condition assertions")
 
   file(REMOVE non_readable_file)
   file(TOUCH non_readable_file)
-  file(CHMOD non_readable_file
-    PERMISSIONS OWNER_WRITE OWNER_EXECUTE GROUP_EXECUTE WORLD_EXECUTE)
+  file(CHMOD non_readable_file PERMISSIONS OWNER_WRITE)
 
   section("it should assert path readability conditions")
     assert(IS_READABLE some_file)
@@ -268,6 +267,28 @@ section("path readability condition assertions")
   endsection()
 endsection()
 
+section("path writability condition assertions")
+  file(TOUCH some_file)
+
+  file(TOUCH non_writable_file)
+  file(CHMOD non_writable_file PERMISSIONS OWNER_READ GROUP_READ WORLD_READ)
+
+  section("it should assert path writability conditions")
+    assert(IS_WRITABLE some_file)
+    assert(NOT IS_WRITABLE non_writable_file)
+  endsection()
+
+  section("it should fail to assert path writability conditions")
+    assert_fatal_error(
+      CALL assert IS_WRITABLE non_writable_file
+      MESSAGE "expected path:\n  non_writable_file\nto be writable")
+
+    assert_fatal_error(
+      CALL assert NOT IS_WRITABLE some_file
+      MESSAGE "expected path:\n  some_file\nnot to be writable")
+  endsection()
+endsection()
+
 section("executable path condition assertions")
   file(TOUCH some_executable)
   file(