update test_coverage to allow running it on crates

The test was assuming that we always want to run all the tests in an
workspace, but that is not the case when we have multiple crates that we
want to publish part of the same workspace.

To address this issue, we can now select to run the coverage test only
on the crate in scope. This can be achieved by passing the parameter
`--test-scope` with the value "crate". By default, tests are still
running as a workspace so that we do not need to update all the other
rust-vmm components that were counting on this feature.

The `test-scope` option can also be reused in other tests that are
making use of `--all`. For example, cargo build.

Signed-off-by: Andreea Florescu <fandree@amazon.com>

integration_tests/test_coverage.py

@@ -1,4 +1,4 @@
-# Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 # SPDX-License-Identifier: Apache-2.0
 """Test the coverage and update the threshold when coverage is increased."""
 
@@ -63,7 +63,7 @@ def _write_coverage_config(coverage_config):
         json.dump(coverage_config, outfile)
 
 
-def _get_current_coverage(coverage_config, no_cleanup):
+def _get_current_coverage(coverage_config, no_cleanup, test_scope):
     """Helper function that returns the coverage computed with kcov."""
     kcov_output_dir = os.path.join(REPO_ROOT_PATH, "kcov_output")
 
@@ -89,11 +89,15 @@ def _get_current_coverage(coverage_config, no_cleanup):
         exclude_pattern += ',' + additional_exclude_path
 
     additional_kcov_param = ''
+
+    if test_scope == pytest.workspace:
+        additional_kcov_param += '--all '
+
     crate_features = coverage_config["crate_features"]
     if crate_features:
         additional_kcov_param += '--features=' + crate_features
 
-    kcov_cmd = "CARGO_TARGET_DIR={} cargo kcov {} --all " \
+    kcov_cmd = "CARGO_TARGET_DIR={} cargo kcov {} " \
                "--output {} -- " \
                "--exclude-region={} " \
                "--exclude-pattern={} " \
@@ -127,15 +131,15 @@ def _get_current_coverage(coverage_config, no_cleanup):
     return coverage
 
 
-def test_coverage(profile, no_cleanup):
+def test_coverage(profile, no_cleanup, test_scope):
     coverage_config = _read_test_config()
-    current_coverage = _get_current_coverage(coverage_config, no_cleanup)
+    current_coverage = _get_current_coverage(coverage_config, no_cleanup, test_scope)
     previous_coverage = coverage_config["coverage_score"]
     if previous_coverage < current_coverage:
         if profile == pytest.profile_ci:
             # In the CI Profile we expect the coverage to be manually updated.
-            assert False,\
-                "Coverage is increased from {} to {}. "\
+            assert False, \
+                "Coverage is increased from {} to {}. " \
                 "Please update the coverage in coverage_config_{}.json."\
                 .format(
                     previous_coverage,