add check for solver installation when initializing solver class instances (#377)

* add check for solver installation when initializing solver class instance

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* refactor check for solver installation using available_solvers and enum

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Apply suggestions from code review

Co-authored-by: Lukas Trippe <[email protected]>

* Apply suggestions from code review

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Lukas Trippe <[email protected]>

Author: 3 people

linopy/solvers.py

@@ -209,6 +209,11 @@ def __init__(
     ):
         self.solver_options = solver_options
 
+        # Check for the solver to be initialized whether the package is installed or not.
+        if self.solver_name.value not in available_solvers:
+            msg = f"Solver package for '{self.solver_name.value}' is not installed. Please install first to initialize solver instance."
+            raise ImportError(msg)
+
     def safe_get_solution(self, status: Status, func: Callable) -> Solution:
         """
         Get solution from function call, if status is unknown still try to run it.
@@ -301,6 +306,10 @@ def solve_problem(
             msg = "No problem file or model specified."
             raise ValueError(msg)
 
+    @property
+    def solver_name(self) -> SolverName:
+        return SolverName[self.__class__.__name__]
+
 
 class CBC(Solver):
     """