no-op if not Windows in tools.vcvars() (conan-io#2608)

* no-op if not Windows in tools.vcvars() and test

* use platform.system() instead of settings

* Removed profiles from test

* fix profiles delete

* review

conans/client/tools/win.py

@@ -346,8 +346,11 @@ def relevant_path(path):
 
 @contextmanager
 def vcvars(*args, **kwargs):
-    new_env = vcvars_dict(*args, **kwargs)
-    with environment_append(new_env):
+    if platform.system() == "Windows":
+        new_env = vcvars_dict(*args, **kwargs)
+        with environment_append(new_env):
+            yield
+    else:
         yield
 
 

conans/test/util/tools_test.py

@@ -576,6 +576,29 @@ def vcvars_constrained_test(self):
                 # Not raising
                 tools.vcvars_command(settings, force=True)
 
+    def vcvars_context_manager_test(self):
+        conanfile = """
+from conans import ConanFile, tools
+
+class MyConan(ConanFile):
+    name = "MyConan"
+    version = "0.1"
+    settings = "os", "compiler"
+
+    def build(self):
+        with tools.vcvars(self.settings):
+            self.output.info("VCINSTALLDIR set to: " + str(tools.get_env("VCINSTALLDIR")))
+"""
+        client = TestClient()
+        client.save({"conanfile.py": conanfile})
+
+        if platform.system() == "Windows":
+            client.run("create . conan/testing")
+            self.assertNotIn("VCINSTALLDIR set to: None", client.out)
+        else:
+            client.run("create . conan/testing")
+            self.assertIn("VCINSTALLDIR set to: None", client.out)
+
     def run_in_bash_test(self):
         if platform.system() != "Windows":
             return