atlas tool: testing via mocking (#18588)

* atlas: refactoring
* Atlas: do some basic testing via mocking

tools/atlas/tests/npeg.nimble

@@ -0,0 +1,48 @@
+# Package
+
+version       = "0.24.1"
+author        = "Ico Doornekamp"
+description   = "a PEG library"
+license       = "MIT"
+srcDir        = "src"
+installExt    = @["nim"]
+
+# Dependencies
+
+requires "nim >= 0.19.0"
+
+# Test
+
+task test, "Runs the test suite":
+  exec "nimble testc && nimble testcpp && nimble testarc && nimble testjs"
+
+task testc, "C tests":
+  exec "nim c -r tests/tests.nim"
+
+task testcpp, "CPP tests":
+  exec "nim cpp -r tests/tests.nim"
+
+task testjs, "JS tests":
+  exec "nim js -r tests/tests.nim"
+
+task testdanger, "Runs the test suite in danger mode":
+  exec "nim c -d:danger -r tests/tests.nim"
+
+task testwin, "Mingw tests":
+  exec "nim c -d:mingw tests/tests.nim && wine tests/tests.exe"
+
+task test32, "32 bit tests":
+  exec "nim c --cpu:i386 --passC:-m32 --passL:-m32 tests/tests.nim && tests/tests"
+
+task testall, "Test all":
+  exec "nimble test && nimble testcpp && nimble testdanger && nimble testjs && nimble testwin"
+
+when (NimMajor, NimMinor) >= (1, 1):
+  task testarc, "--gc:arc tests":
+    exec "nim c --gc:arc -r tests/tests.nim"
+else:
+  task testarc, "--gc:arc tests":
+    exec "true"
+
+task perf, "Test performance":
+  exec "nim cpp -r -d:danger tests/performance.nim"