Make assert handling less error-prone

Prevent my future self or other contributors from using assert in
tests and then having that assert not do anything because of the
NDEBUG macro.

28 files changed, 191 insertions, 130 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 72bf5a95..3e50f0b5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -305,6 +305,10 @@ if(GENERATE_AUTO_JOB)
   add_custom_target(auto_job_files ALL DEPENDS ${auto_job_outputs})
 endif()
 
+add_test(
+  NAME check-assert
+  COMMAND perl ${qpdf_SOURCE_DIR}/check_assert)
+
 # add_subdirectory order affects test order
 add_subdirectory(include)
 add_subdirectory(libqpdf)
diff --git a/README-maintainer b/README-maintainer
index 2e11a11b..88e81461 100644
--- a/README-maintainer
+++ b/README-maintainer
@@ -123,11 +123,23 @@ CODING RULES
   "Code Formatting" section in manual/contributing.rst for details.
   See also "CODE FORMATTING" below.
 
-* Do not use assert in non-test code for any purpose other than as a
-  sanity check during development that would be safe to remove in
-  production. assert is for strong invariant checking. When developing
-  and using assert for that purpose, make sure to use the Debug
-  configuration since assert is disabled in other configurations.
+* Use of assert:
+
+  * Test code: #include <qpdf/assert_test.h> first.
+  * Debug code: #include <qpdf/assert_debug.h> first and use
+    qpdf_assert_debug instead of assert.
+
+  These rules are enforced by the check-assert test. This practices
+  serves to
+
+  * remind us that assert in release code disappears and so should only
+    be used for debugging; when doing so use a Debug build
+    configuration
+
+  * protect us from using assert in test code without explicitly
+    removing the NDEBUG definition, since that would cause the assert
+    not to actually be testing anything in non-Debug build
+    configurations.
 
 * In a source file, include the header file that declares the source
   class first followed by a blank line. If a config file is needed
diff --git a/check_assert b/check_assert
new file mode 100755
index 00000000..81ecf788
--- /dev/null
+++ b/check_assert
@@ -0,0 +1,62 @@
+#!/usr/bin/env perl
+require 5.008;
+use warnings;
+use strict;
+use File::Basename;
+
+my $whoami = basename($0);
+chdir(dirname($0)) or die;
+
+my $errors = 0;
+foreach my $file (glob('*/*.c'), glob('*/*.cc'),
+                  glob('*/*/*.h'), glob('*/*/*.hh'))
+{
+    my $assert_test = 0;
+    if ($file =~ m,^libqpdf/qpdf/assert_,)
+    {
+        next;
+    }
+    open(F, "<$file") or die;
+    my $first_include = undef;
+    while (<F>)
+    {
+        if (m,^\s*#\s*include <qpdf/assert_(.*?).h>,)
+        {
+            if ($1 eq 'test')
+            {
+                $assert_test = 1;
+            }
+            if (defined $first_include)
+            {
+                error("$file:$.: qpdf/assert header must be first");
+            }
+        }
+        if (m,^\s*#\s*include <(.*?)>,)
+        {
+            my $header = $1;
+            if (($header eq 'cassert') || ($header eq 'assert.h'))
+            {
+                error("$file:$.: assert.h and cassert are not allowed --" .
+                      " use one of the qpdf/assert_ files instead");
+            }
+            $first_include = 1;
+        }
+        if ((! $assert_test) && (m/assert\(/))
+        {
+            error("$file:$.: call qpdf_assert_debug instead of assert");
+        }
+    }
+    close(F);
+}
+if ($errors)
+{
+    die "$whoami: errors detected\n";
+}
+print "$whoami: no incorrect use of assert found\n";
+
+sub error
+{
+    my $msg = shift;
+    warn $msg, "\n";
+    $errors = 1;
+}
diff --git a/include/qpdf/QIntC.hh b/include/qpdf/QIntC.hh
index ce2f47e9..dadc7582 100644
--- a/include/qpdf/QIntC.hh
+++ b/include/qpdf/QIntC.hh
@@ -24,7 +24,6 @@
 
 #include <qpdf/DLL.h>
 #include <qpdf/Types.h>
-#include <cassert>
 #include <iostream>
 #include <limits>
 #include <locale>
diff --git a/libqpdf/QPDFWriter.cc b/libqpdf/QPDFWriter.cc
index e5270449..103abee1 100644
--- a/libqpdf/QPDFWriter.cc
+++ b/libqpdf/QPDFWriter.cc
@@ -1,4 +1,6 @@
-#include <qpdf/qpdf-config.h> // include first for large file support
+#include <qpdf/assert_debug.h>
+
+#include <qpdf/qpdf-config.h> // include early for large file support
 
 #include <qpdf/QPDFWriter.hh>
 
@@ -21,7 +23,6 @@
 #include <qpdf/RC4.hh>
 
 #include <algorithm>
-#include <cassert>
 #include <stdlib.h>
 
 QPDFWriter::Members::Members(QPDF& pdf) :
@@ -996,7 +997,7 @@ QPDFWriter::writePad(int nspaces)
 Pipeline*
 QPDFWriter::pushPipeline(Pipeline* p)
 {
-    assert(dynamic_cast<Pl_Count*>(p) == 0);
+    qpdf_assert_debug(dynamic_cast<Pl_Count*>(p) == 0);
     this->m->pipeline_stack.push_back(p);
     return p;
 }
@@ -1027,9 +1028,9 @@ QPDFWriter::PipelinePopper::~PipelinePopper()
     if (stack_id.empty()) {
         return;
     }
-    assert(qw->m->pipeline_stack.size() >= 2);
+    qpdf_assert_debug(qw->m->pipeline_stack.size() >= 2);
     qw->m->pipeline->finish();
-    assert(
+    qpdf_assert_debug(
         dynamic_cast<Pl_Count*>(qw->m->pipeline_stack.back()) ==
         qw->m->pipeline);
     // It might be possible for this assertion to fail if
@@ -1038,7 +1039,7 @@ QPDFWriter::PipelinePopper::~PipelinePopper()
     // which two dynamically allocated PipelinePopper objects ever
     // exist at the same time, so the assertion will fail if they get
     // popped out of order from automatic destruction.
-    assert(qw->m->pipeline->getIdentifier() == stack_id);
+    qpdf_assert_debug(qw->m->pipeline->getIdentifier() == stack_id);
     delete qw->m->pipeline_stack.back();
     qw->m->pipeline_stack.pop_back();
     while (dynamic_cast<Pl_Count*>(qw->m->pipeline_stack.back()) == 0) {
@@ -1109,9 +1110,9 @@ QPDFWriter::pushMD5Pipeline(PipelinePopper& pp)
         throw std::logic_error("Deterministic ID computation enabled after ID"
                                " generation has already occurred.");
     }
-    assert(this->m->deterministic_id);
-    assert(this->m->md5_pipeline == 0);
-    assert(this->m->pipeline->getCount() == 0);
+    qpdf_assert_debug(this->m->deterministic_id);
+    qpdf_assert_debug(this->m->md5_pipeline == 0);
+    qpdf_assert_debug(this->m->pipeline->getCount() == 0);
     this->m->md5_pipeline = new Pl_MD5("qpdf md5", this->m->pipeline);
     this->m->md5_pipeline->persistAcrossFinish(true);
     // Special case code in popPipelineStack clears this->m->md5_pipeline
@@ -1123,8 +1124,8 @@ QPDFWriter::pushMD5Pipeline(PipelinePopper& pp)
 void
 QPDFWriter::computeDeterministicIDData()
 {
-    assert(this->m->md5_pipeline != 0);
-    assert(this->m->deterministic_id_data.empty());
+    qpdf_assert_debug(this->m->md5_pipeline != 0);
+    qpdf_assert_debug(this->m->deterministic_id_data.empty());
     this->m->deterministic_id_data = this->m->md5_pipeline->getHexDigest();
     this->m->md5_pipeline->enable(false);
 }
@@ -1786,7 +1787,7 @@ QPDFWriter::writeObjectStream(QPDFObjectHandle object)
     // object stream that we are generating from scratch.
 
     QPDFObjGen old_og = object.getObjGen();
-    assert(old_og.getGen() == 0);
+    qpdf_assert_debug(old_og.getGen() == 0);
     int old_id = old_og.getObj();
     int new_id = this->m->obj_renumber[old_og];
 
@@ -3003,7 +3004,7 @@ QPDFWriter::writeLinearized()
         closeObject(lindict_id);
         static int const pad = 200;
         int spaces = QIntC::to_int(pos - this->m->pipeline->getCount() + pad);
-        assert(spaces >= 0);
+        qpdf_assert_debug(spaces >= 0);
         writePad(spaces);
         writeString("\n");
 
@@ -3177,7 +3178,7 @@ QPDFWriter::writeLinearized()
                     need_xref_stream ? 0 : 1);
                 computeDeterministicIDData();
                 pp_md5 = 0;
-                assert(this->m->md5_pipeline == 0);
+                qpdf_assert_debug(this->m->md5_pipeline == 0);
             }
 
             // Close first pass pipeline
@@ -3377,6 +3378,6 @@ QPDFWriter::writeStandard()
             "QPDFWriter standard deterministic ID",
             this->m->object_stream_to_objects.empty() ? 0 : 1);
         pp_md5 = 0;
-        assert(this->m->md5_pipeline == 0);
+        qpdf_assert_debug(this->m->md5_pipeline == 0);
     }
 }
diff --git a/libqpdf/QPDF_encryption.cc b/libqpdf/QPDF_encryption.cc
index 14b22d88..6a9ad871 100644
--- a/libqpdf/QPDF_encryption.cc
+++ b/libqpdf/QPDF_encryption.cc
@@ -1,6 +1,8 @@
 // This file implements methods from the QPDF class that involve
 // encryption.
 
+#include <qpdf/assert_debug.h>
+
 #include <qpdf/QPDF.hh>
 
 #include <qpdf/QPDFExc.hh>
@@ -15,7 +17,6 @@
 #include <qpdf/RC4.hh>
 
 #include <algorithm>
-#include <cassert>
 #include <string.h>
 
 static unsigned char const padding_string[] = {
@@ -288,7 +289,7 @@ hash_V5(
 
             ++round_number;
             std::string K1 = password + K + udata;
-            assert(K.length() >= 32);
+            qpdf_assert_debug(K.length() >= 32);
             std::string E = process_with_aes(
                 K.substr(0, 16),
                 true,
diff --git a/libqpdf/QPDF_optimization.cc b/libqpdf/QPDF_optimization.cc
index ac1bbfe6..4204a20d 100644
--- a/libqpdf/QPDF_optimization.cc
+++ b/libqpdf/QPDF_optimization.cc
@@ -1,12 +1,13 @@
 // See the "Optimization" section of the manual.
 
+#include <qpdf/assert_debug.h>
+
 #include <qpdf/QPDF.hh>
 
 #include <qpdf/QPDFExc.hh>
 #include <qpdf/QPDF_Array.hh>
 #include <qpdf/QPDF_Dictionary.hh>
 #include <qpdf/QTC.hh>
-#include <cassert>
 
 QPDF::ObjUser::ObjUser() :
     ou_type(ou_bad),
@@ -18,14 +19,14 @@ QPDF::ObjUser::ObjUser(user_e type) :
     ou_type(type),
     pageno(0)
 {
-    assert(type == ou_root);
+    qpdf_assert_debug(type == ou_root);
 }
 
 QPDF::ObjUser::ObjUser(user_e type, int pageno) :
     ou_type(type),
     pageno(pageno)
 {
-    assert((type == ou_page) || (type == ou_thumb));
+    qpdf_assert_debug((type == ou_page) || (type == ou_thumb));
 }
 
 QPDF::ObjUser::ObjUser(user_e type, std::string const& key) :
@@ -33,7 +34,7 @@ QPDF::ObjUser::ObjUser(user_e type, std::string const& key) :
     pageno(0),
     key(key)
 {
-    assert((type == ou_trailer_key) || (type == ou_root_key));
+    qpdf_assert_debug((type == ou_trailer_key) || (type == ou_root_key));
 }
 
 bool
diff --git a/libqpdf/qpdf/assert_debug.h b/libqpdf/qpdf/assert_debug.h
new file mode 100644
index 00000000..0543d8fb
--- /dev/null
+++ b/libqpdf/qpdf/assert_debug.h
@@ -0,0 +1,18 @@
+/*
+ * Include this file to use assert in regular code for
+ * debugging/strong sanity checking, knowing that the assert will be
+ * disabled in release code. Use qpdf_assert_debug in the code.
+ */
+
+/* assert_debug and assert_test intentionally use the same
+ * guard. Search for assert in README-MAINTAINER.
+ */
+#ifdef QPDF_ASSERT_H
+# error "At most one qpdf/assert header may be included at most one time"
+#else
+# define QPDF_ASSERT_H
+
+# include <assert.h>
+# define qpdf_assert_debug assert
+
+#endif /* QPDF_ASSERT_H */
diff --git a/libqpdf/qpdf/assert_test.h b/libqpdf/qpdf/assert_test.h
new file mode 100644
index 00000000..5310cdaa
--- /dev/null
+++ b/libqpdf/qpdf/assert_test.h
@@ -0,0 +1,20 @@
+/*
+ * Include this file to use assert in regular code for
+ * debugging/strong sanity checking, knowing that the assert will be
+ * disabled in release code. Use qpdf_debug_assert in the code.
+ */
+
+/* assert_debug and assert_test intentionally use the same
+ * guard. Search for assert in README-MAINTAINER.
+ */
+#ifdef QPDF_ASSERT_H
+# error "At most one qpdf/assert header may be included at most one time"
+#else
+# define QPDF_ASSERT_H
+
+# ifdef NDEBUG
+#  undef NDEBUG
+# endif
+# include <assert.h>
+
+#endif /* QPDF_ASSERT_H */
diff --git a/libtests/arg_parser.cc b/libtests/arg_parser.cc
index 8b4d556a..1480a717 100644
--- a/libtests/arg_parser.cc
+++ b/libtests/arg_parser.cc
@@ -1,15 +1,11 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/QPDFArgParser.hh>
 #include <qpdf/QPDFUsage.hh>
 #include <qpdf/QUtil.hh>
 #include <cstring>
 #include <iostream>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 class ArgParser
 {
   public:
diff --git a/libtests/base64.cc b/libtests/base64.cc
index 66f2d828..0ce6f9a3 100644
--- a/libtests/base64.cc
+++ b/libtests/base64.cc
@@ -1,8 +1,9 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/Pl_Base64.hh>
 
 #include <qpdf/Pl_StdioFile.hh>
 #include <qpdf/QUtil.hh>
-#include <cassert>
 #include <cstdlib>
 #include <cstring>
 #include <iostream>
diff --git a/libtests/buffer.cc b/libtests/buffer.cc
index a24c0f99..a65efb1c 100644
--- a/libtests/buffer.cc
+++ b/libtests/buffer.cc
@@ -1,3 +1,5 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/Pl_Buffer.hh>
 #include <qpdf/Pl_Count.hh>
 #include <qpdf/Pl_Discard.hh>
@@ -7,12 +9,6 @@
 #include <stdexcept>
 #include <stdlib.h>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 static unsigned char*
 uc(char const* s)
 {
diff --git a/libtests/concatenate.cc b/libtests/concatenate.cc
index 10902adf..9bc0fd04 100644
--- a/libtests/concatenate.cc
+++ b/libtests/concatenate.cc
@@ -1,15 +1,11 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/Pl_Buffer.hh>
 #include <qpdf/Pl_Concatenate.hh>
 #include <qpdf/Pl_Flate.hh>
 #include <qpdf/QUtil.hh>
 #include <iostream>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 static void
 pipeStringAndFinish(Pipeline* p, std::string const& str)
 {
diff --git a/libtests/cxx11.cc b/libtests/cxx11.cc
index 4c2c2cb6..250e7e2b 100644
--- a/libtests/cxx11.cc
+++ b/libtests/cxx11.cc
@@ -1,3 +1,5 @@
+#include <qpdf/assert_test.h>
+
 #include <cstdint>
 #include <cstdlib>
 #include <cstring>
@@ -9,12 +11,6 @@
 #include <type_traits>
 #include <vector>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 // Functional programming
 
 // Function that returns a callable in the form of a lambda
diff --git a/libtests/json.cc b/libtests/json.cc
index 43f2b3c6..3844222f 100644
--- a/libtests/json.cc
+++ b/libtests/json.cc
@@ -1,13 +1,9 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/JSON.hh>
 #include <qpdf/QPDFObjectHandle.hh>
 #include <iostream>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 static void
 check(JSON const& j, std::string const& exp)
 {
diff --git a/libtests/json_handler.cc b/libtests/json_handler.cc
index 567cde86..4e610b08 100644
--- a/libtests/json_handler.cc
+++ b/libtests/json_handler.cc
@@ -1,14 +1,10 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/JSONHandler.hh>
 #include <qpdf/QPDFUsage.hh>
 #include <qpdf/QUtil.hh>
 #include <iostream>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 static void
 print_null(std::string const& path)
 {
diff --git a/libtests/matrix.cc b/libtests/matrix.cc
index 7dc73390..f69d270c 100644
--- a/libtests/matrix.cc
+++ b/libtests/matrix.cc
@@ -1,13 +1,9 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/QPDFMatrix.hh>
 #include <qpdf/QUtil.hh>
 #include <iostream>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 static void
 check(QPDFMatrix const& m, std::string const& exp)
 {
diff --git a/libtests/pdf_version.cc b/libtests/pdf_version.cc
index e9bfb00b..5db444b3 100644
--- a/libtests/pdf_version.cc
+++ b/libtests/pdf_version.cc
@@ -1,13 +1,9 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/PDFVersion.hh>
 
 #include <iostream>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 int
 main()
 {
diff --git a/libtests/predictors.cc b/libtests/predictors.cc
index c024cbd6..a8f6c5d9 100644
--- a/libtests/predictors.cc
+++ b/libtests/predictors.cc
@@ -1,3 +1,5 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/Pl_PNGFilter.hh>
 #include <qpdf/Pl_StdioFile.hh>
 #include <qpdf/Pl_TIFFPredictor.hh>
@@ -9,12 +11,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 void
 run(char const* filename,
     char const* filter,
diff --git a/libtests/qintc.cc b/libtests/qintc.cc
index d3e19f5b..d5738a4b 100644
--- a/libtests/qintc.cc
+++ b/libtests/qintc.cc
@@ -1,12 +1,8 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/QIntC.hh>
 #include <stdint.h>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 #define try_convert(exp_pass, fn, i) \
  try_convert_real(#fn "(" #i ")", exp_pass, fn, i)
 
diff --git a/libtests/qutil.cc b/libtests/qutil.cc
index 017f371b..f79f9a3f 100644
--- a/libtests/qutil.cc
+++ b/libtests/qutil.cc
@@ -1,3 +1,5 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/Pl_Buffer.hh>
 #include <qpdf/QPDFSystemError.hh>
 #include <qpdf/QUtil.hh>
@@ -17,12 +19,6 @@
 # include <unistd.h>
 #endif
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 template <class int_T>
 void
 test_to_number(
diff --git a/libtests/rc4.cc b/libtests/rc4.cc
index 7245ef86..1b1a8744 100644
--- a/libtests/rc4.cc
+++ b/libtests/rc4.cc
@@ -1,3 +1,5 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/Pl_RC4.hh>
 #include <qpdf/Pl_StdioFile.hh>
 #include <qpdf/QIntC.hh>
@@ -8,12 +10,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 static void
 other_tests()
 {
diff --git a/libtests/sparse_array.cc b/libtests/sparse_array.cc
index 8d37bc2f..62410399 100644
--- a/libtests/sparse_array.cc
+++ b/libtests/sparse_array.cc
@@ -1,12 +1,8 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/SparseOHArray.hh>
 #include <iostream>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 int
 main()
 {
diff --git a/qpdf/CMakeLists.txt b/qpdf/CMakeLists.txt
index 94cf9e2d..bc4ddf11 100644
--- a/qpdf/CMakeLists.txt
+++ b/qpdf/CMakeLists.txt
@@ -29,6 +29,16 @@ endforeach()
 target_include_directories(qpdf-ctest PRIVATE ${CMAKE_BINARY_DIR}/libqpdf)
 target_include_directories(sizes PRIVATE ${JPEG_INCLUDE})
 
+set(needs_private_headers
+  test_large_file
+  test_driver
+  qpdf-ctest
+  qpdfjob-ctest
+  )
+foreach(TARGET ${needs_private_headers})
+  target_include_directories(${TARGET} PRIVATE ${CMAKE_SOURCE_DIR}/libqpdf)
+endforeach()
+
 foreach(B qpdf test_unicode_filenames fix-qdf test_shell_glob)
   if(WINDOWS_WMAIN_COMPILE)
     target_compile_options(${B} PRIVATE ${WINDOWS_WMAIN_COMPILE})
diff --git a/qpdf/qpdf-ctest.c b/qpdf/qpdf-ctest.c
index 62274c52..07d6ca9e 100644
--- a/qpdf/qpdf-ctest.c
+++ b/qpdf/qpdf-ctest.c
@@ -1,3 +1,5 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/qpdf-c.h>
 #include <errno.h>
 #include <stdio.h>
@@ -6,12 +8,6 @@
 
 #include <qpdf/qpdf-config.h> // for LL_FMT -- special case in build
 
-#ifdef NDEBUG
-/* We need assert even in a release build for test code. */
-# undef NDEBUG
-#endif
-#include <assert.h>
-
 static char* whoami = 0;
 static qpdf_data qpdf = 0;
 
diff --git a/qpdf/qpdfjob-ctest.c b/qpdf/qpdfjob-ctest.c
index e67890e8..8d5e374e 100644
--- a/qpdf/qpdfjob-ctest.c
+++ b/qpdf/qpdfjob-ctest.c
@@ -1,14 +1,10 @@
+#include <qpdf/assert_test.h>
+
 #include <qpdf/qpdfjob-c.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-#ifdef NDEBUG
-/* We need assert even in a release build for test code. */
-# undef NDEBUG
-#endif
-#include <assert.h>
-
 #ifndef QPDF_NO_WCHAR_T
 static void
 wide_test()
diff --git a/qpdf/test_driver.cc b/qpdf/test_driver.cc
index f0c56176..1934b02b 100644
--- a/qpdf/test_driver.cc
+++ b/qpdf/test_driver.cc
@@ -1,3 +1,5 @@
+#include <qpdf/assert_test.h>
+
 // This program tests miscellaneous functionality in the qpdf library
 // that we don't want to pollute the qpdf program with.
 
@@ -32,12 +34,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 static char const* whoami = 0;
 
 void
diff --git a/qpdf/test_large_file.cc b/qpdf/test_large_file.cc
index 32494426..904f3dd6 100644
--- a/qpdf/test_large_file.cc
+++ b/qpdf/test_large_file.cc
@@ -1,3 +1,5 @@
+#include <qpdf/assert_test.h>
+
 // NOTE: This test program doesn't do anything special to enable large
 // file support.  This is important since it verifies that programs
 // don't have to do anything special -- all the work is done
@@ -14,12 +16,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#ifdef NDEBUG
-// We need assert even in a release build for test code.
-# undef NDEBUG
-#endif
-#include <cassert>
-
 // Run "test_large_file write small a.pdf" to get a PDF file that you
 // can look at in a reader.