add rcha codec test

Author: mjreno

test/test_mf6_codec.py

@@ -302,6 +302,48 @@ def test_dumps_chdg():
     pprint(loaded)
 
 
+def test_dumps_rcha():
+    from flopy4.mf6.gwf import Dis, Gwf, Rcha
+
+    nlay = 3
+    nrow = 10
+    ncol = 10
+
+    dis = Dis(nlay=nlay, nrow=nrow, ncol=ncol)
+    gwf = Gwf(dis=dis)
+
+    recharge = np.full((nrow, ncol), FILL_DNODATA, dtype=float)
+    recharge[0, 0] = 1.0
+    recharge[9, 9] = 0.0
+    rch = Rcha(
+        parent=gwf,
+        recharge=np.expand_dims(recharge.ravel(), axis=0),
+        save_flows=True,
+        print_input=True,
+        dims={"nper": 1},
+    )
+
+    dumped = dumps(COMPONENT_CONVERTER.unstructure(rch))
+    print("RCH dump:")
+    print(dumped)
+
+    assert "BEGIN PERIOD 1" in dumped
+    assert "END PERIOD 1" in dumped
+
+    period_section = dumped.split("BEGIN PERIOD 1")[1].split("END PERIOD 1")[0].strip()
+    lines = [line.strip() for line in period_section.split("\n") if line.strip()]
+
+    assert len(lines) == 3
+    assert "READASARRAYS" in dumped
+    dump_data = [float(x) for x in lines[2].split()]
+    dump_recharge = np.array(dump_data)
+    assert np.allclose(recharge, dump_recharge.reshape(nrow, ncol))
+
+    loaded = loads(dumped)
+    print("RCHA load:")
+    pprint(loaded)
+
+
 def test_dumps_wel():
     from flopy4.mf6.gwf import Dis, Gwf, Wel