4567 - support automated tests in SubX

All it takes is to code-generate a simple function called 'run_tests' that
calls all functions starting with 'test_' one by one.

I've temporarily switched the factorial app to run as a test. But that's
temporary, because all the code to print '.' vs 'F' needs to get extracted
out into a helper.

3 files changed, 179 insertions, 11 deletions

diff --git a/subx/040---tests.cc b/subx/040---tests.cc
new file mode 100644
index 00000000..10356174
--- /dev/null
+++ b/subx/040---tests.cc
@@ -0,0 +1,104 @@
+//: Beginning of level 3: support for automatically aggregating functions into
+//: test suites.
+//:
+//: (As explained in the transform layer, level 3 runs before level 2. We
+//: can't use any of the transforms in previous layers. But we *do* rely on
+//: those concepts being present in the input. Particularly labels.)
+
+:(after "Begin Transforms")
+// Begin Level-3 Transforms
+Transform.push_back(create_test_function);
+// End Level-3 Transforms
+
+:(scenario run_test)
+% Reg[ESP].u = 0x100;
+== 0x1
+main:
+  e8/call run_tests/disp32  # 5 bytes
+  f4/halt                   # 1 byte
+
+test_foo:  # offset 7
+  01 d8  # just some unique instruction: add EBX to EAX
+  c3/return
+
+# check that code in test_foo ran (implicitly called by run_tests)
++run: inst: 0x00000007
+
+:(code)
+void create_test_function(program& p) {
+  if (p.segments.empty()) return;
+  segment& code = p.segments.at(0);
+  trace(99, "transform") << "-- create 'run_tests'" << end();
+  vector<line> new_insts;
+  for (int i = 0;  i < SIZE(code.lines);  ++i) {
+    line& inst = code.lines.at(i);
+    for (int j = 0;  j < SIZE(inst.words);  ++j) {
+      const word& curr = inst.words.at(j);
+      if (*curr.data.rbegin() != ':') continue;  // not a label
+      if (!starts_with(curr.data, "test_")) continue;
+      string fn = drop_last(curr.data);
+      new_insts.push_back(call(fn));
+    }
+  }
+  if (new_insts.empty()) return;  // no tests found
+  code.lines.push_back(label("run_tests"));
+  code.lines.insert(code.lines.end(), new_insts.begin(), new_insts.end());
+  code.lines.push_back(ret());
+}
+
+string to_string(const segment& s) {
+  ostringstream out;
+  for (int i = 0;  i < SIZE(s.lines);  ++i) {
+    const line& l = s.lines.at(i);
+    for (int j = 0;  j < SIZE(l.words);  ++j) {
+      if (j > 0) out << ' ';
+      out << to_string(l.words.at(j));
+    }
+    out << '\n';
+  }
+  return out.str();
+}
+
+string to_string(const word& w) {
+  ostringstream out;
+  out << w.data;
+  for (int i = 0;  i < SIZE(w.metadata);  ++i)
+    out << '/' << w.metadata.at(i);
+  return out.str();
+}
+
+line label(string s) {
+  line result;
+  result.words.push_back(word());
+  result.words.back().data = (s+":");
+  return result;
+}
+
+line call(string s) {
+  line result;
+  result.words.push_back(call());
+  result.words.push_back(disp32(s));
+  return result;
+}
+
+word call() {
+  word result;
+  result.data = "e8";
+  result.metadata.push_back("call");
+  return result;
+}
+
+word disp32(string s) {
+  word result;
+  result.data = s;
+  result.metadata.push_back("disp32");
+  return result;
+}
+
+line ret() {
+  line result;
+  result.words.push_back(word());
+  result.words.back().data = "c3";
+  result.words.back().metadata.push_back("return");
+  return result;
+}
diff --git a/subx/apps/factorial b/subx/apps/factorial
index e60e7d21..15fa68ec 100755
--- a/subx/apps/factorial
+++ b/subx/apps/factorial
Binary files differdiff --git a/subx/apps/factorial.subx b/subx/apps/factorial.subx
index 31821dce..d71ea455 100644
--- a/subx/apps/factorial.subx
+++ b/subx/apps/factorial.subx
@@ -13,17 +13,18 @@
 # 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes
 
 # main:
-  # prepare to make a call
-  55/push                         .               .             .           .             .           .           .               .                 # push EBP
-  89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
-  # factorial(5)
-  68/push                         .               .             .           .             .           .           .               5/imm32           # push 5
-  e8/call                         .               .             .           .             .           .           factorial/disp32
-  # discard arg
-  81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add 4 to ESP
-  # clean up after call
-  89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
-  5d/pop                          .               .             .           .             .           .           .               .                 # pop to EBP
+  e8/call run_tests/disp32
+#?   # prepare to make a call
+#?   55/push                         .               .             .           .             .           .           .               .                 # push EBP
+#?   89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
+#?   # factorial(5)
+#?   68/push                         .               .             .           .             .           .           .               5/imm32           # push 5
+#?   e8/call                         .               .             .           .             .           .           factorial/disp32
+#?   # discard arg
+#?   81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add 4 to ESP
+#?   # clean up after call
+#?   89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
+#?   5d/pop                          .               .             .           .             .           .           .               .                 # pop to EBP
 
   # exit(EAX)
   89/copy                         3/mod/direct    3/rm32/EBX    .           .             .           0/r32/EAX   .               .                 # copy EAX to EBX
@@ -59,4 +60,67 @@ factorial:
 $factorial:exit:
   c3/return
 
+test_factorial:
+  # factorial(5)
+    # push arg
+  68/push                         .               .             .           .             .           .           .               5/imm32           # push 5
+    # call
+  e8/call                         .               .             .           .             .           .           factorial/disp32
+    # discard arg
+  81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add 4 to ESP
+  # if EAX == 120
+  3d/compare                      .               .             .           .             .           .           .               0x78/imm32/120    # compare EAX with 120
+  75/jump-if-unequal              .               .             .           .             .           .           $test_factorial:else/disp8
+    # print('.')
+      # push args
+  68/push                         .               .             .           .             .           .           .               Test_passed/imm32
+      # call
+  e8/call                         .               .             .           .             .           .           write_stderr/disp32
+      # discard arg
+  81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add 4 to ESP
+    # return
+  c3/return
+  # else:
+$test_factorial:else:
+    # print('F')
+      # push args
+  68/push                         .               .             .           .             .           .           .               Test_failed/imm32
+      # call
+  e8/call                         .               .             .           .             .           .           write_stderr/disp32
+      # discard arg
+  81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add 4 to ESP
+  # end
+  c3/return
+
+## helpers
+
+write_stderr:  # s : (address array byte) -> <void>
+  # write(2/stderr, (data) s+4, (size) *s)
+    # fd = 2 (stderr)
+  bb/copy                         .               .             .           .             .           .           .               2/imm32           # copy 2 to EBX
+    # x = s+4
+  8b/copy                         1/mod/*+disp8   4/rm32/SIB    4/base/ESP  4/index/none  .           1/r32/ECX   4/disp8         .                 # copy *(ESP+4) to ECX
+  81          0/subop/add         3/mod/direct    1/rm32/ECX    .           .             .           .           .               4/imm32           # add 4 to ECX
+    # size = *s
+  8b/copy                         1/mod/*+disp8   4/rm32/SIB    4/base/ESP  4/index/none  .           2/r32/EDX   4/disp8         .                 # copy *(ESP+4) to EDX
+  8b/copy                         0/mod/indirect  2/rm32/EDX    .           .             .           2/r32/EDX   .               .                 # copy *EDX to EDX
+    # call write()
+  b8/copy                         .               .             .           .             .           .           .               4/imm32/write     # copy 1 to EAX
+  cd/syscall                      .               .             .           .             .           .           .               0x80/imm8         # int 80h
+  # end
+  c3/return
+
+== data
+Test_passed:
+  # size
+  01 00 00 00
+  # data
+  2e/dot
+
+Test_failed:
+  # size
+  01 00 00 00
+  # data
+  46/F
+
 # vim:ft=subx:nowrap:so=0