Update error handling to improve UX

Add discrete exception for version conflict vs not in lockfile errors
Update to set tox venv to failed when conflict happens
Update tox reporting for errors to use proper level

tox_poetry_installer.py

@@ -60,8 +60,12 @@ class ToxPoetryInstallerException(Exception):
     """Error while installing locked dependencies to the test environment"""
 
 
-class NoLockedDependencyError(ToxPoetryInstallerException):
-    """Cannot install a package that is not in the lockfile"""
+class LockedDepVersionConflictError(ToxPoetryInstallerException):
+    """Locked dependencies cannot specify an alternate version for installation"""
+
+
+class LockedDepNotFoundError(ToxPoetryInstallerException):
+    """Locked dependency was not found in the lockfile"""
 
 
 def _sort_env_deps(venv: ToxVirtualEnv) -> _SortedEnvDeps:
@@ -172,12 +176,11 @@ def _find_transients(poetry: Poetry, dependency_name: str) -> List[PoetryPackage
         if any(
             delimiter in dependency_name for delimiter in _PEP508_VERSION_DELIMITERS
         ):
-            message = "cannot specify a version for a locked env dependency"
-        else:
-            message = "no version of the env dependency was found in the current project's lockfile"
-
-        raise NoLockedDependencyError(
-            f"Cannot install env dependency '{dependency_name}': {message}"
+            raise LockedDepVersionConflictError(
+                f"Locked dependency '{dependency_name}' cannot include version specifier"
+            ) from None
+        raise LockedDepNotFoundError(
+            f"No version of locked dependency '{dependency_name}' found in the project lockfile"
         ) from None
 
 
@@ -191,7 +194,12 @@ def _install_env_dependencies(venv: ToxVirtualEnv, poetry: Poetry):
 
     dependencies: List[PoetryPackage] = []
     for dep in env_deps.locked_deps:
-        dependencies += _find_transients(poetry, dep.name)
+        try:
+            dependencies += _find_transients(poetry, dep.name)
+        except ToxPoetryInstallerException as err:
+            venv.status = "install-locked-deps-failed"
+            reporter.error(f"{_REPORTER_PREFIX} {err}")
+            raise err
 
     reporter.verbosity1(
         f"{_REPORTER_PREFIX} identified {len(dependencies)} actual dependencies from {len(venv.envconfig.deps)} specified env dependencies"