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.

1 files changed, 104 insertions, 0 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;
+}