stage: fix --dry-run (#3799)

* tests: unit: move stage tests into a separate dir

* stage: fix --dry-run

Part of #3777

dvc/stage/run.py

@@ -78,6 +78,7 @@ def cmd_run(stage, *args, **kwargs):
 
 def run_stage(stage, dry=False, force=False, run_cache=False):
     if dry:
+        logger.info("Running command:\n\t{}".format(stage.cmd))
         return
     stage_cache = stage.repo.stage_cache
     stage_cached = (

tests/unit/stage/test_run.py

@@ -0,0 +1,10 @@
+import logging
+
+from dvc.stage import Stage
+from dvc.stage.run import run_stage
+
+
+def test_run_stage_dry(caplog):
+    with caplog.at_level(level=logging.INFO, logger="dvc"):
+        run_stage(Stage(None, cmd="mycmd arg1 arg2"), dry=True)
+        assert caplog.messages == ["Running command:\n\tmycmd arg1 arg2"]