* Adding a test for all PINN solvers to assert that the metrics are correctly log

* Adding test for Metric Tracker
* Modify Metric Tracker to correctly log metrics

tests/test_solvers/test_competitive_pinn.py

@@ -163,6 +163,17 @@ def test_train_cpu():
                       accelerator='cpu', batch_size=20)
     trainer.train()
 
+def test_log():
+    poisson_problem.discretise_domain(100)
+    solver = PINN(problem = poisson_problem, model=model, loss=LpLoss())
+    trainer = Trainer(solver, max_epochs=2, accelerator='cpu')
+    trainer.train()
+    # assert the logged metrics are correct
+    logged_metrics = sorted(list(trainer.logged_metrics.keys()))
+    total_metrics = sorted(
+        list([key + '_loss' for key in poisson_problem.conditions.keys()])
+        + ['mean_loss'])
+    assert logged_metrics == total_metrics
 
 def test_train_restore():
     tmpdir = "tests/tmp_restore"