migrate some Cache tests to integration tests

build_tests/two_sources/cache_strict_deps.rb

@@ -0,0 +1,19 @@
+class StrictBuilder < Rscons::Builder
+  def run(options)
+    target, sources, cache, env = options.values_at(:target, :sources, :cache, :env)
+    command = %W[gcc -o #{target}] + sources.sort
+    unless cache.up_to_date?(target, command, sources, env, strict_deps: true)
+      return false unless env.execute("StrictBuilder #{target}", command)
+      cache.register_build(target, command, sources, env)
+    end
+    target
+  end
+end
+
+Rscons::Environment.new(echo: :command) do |env|
+  env.add_builder(StrictBuilder.new)
+  env.Object("one.o", "one.c", "CCFLAGS" => %w[-DONE])
+  env.Object("two.o", "two.c")
+  sources = File.read("sources", mode: "rb").split(" ")
+  env.StrictBuilder("program.exe", sources)
+end