r.latlong: Add tests (#5523)

Author: Shreshth-Malik

raster/r.latlong/tests/test_r_latlong.py

@@ -0,0 +1,175 @@
+import os
+import pytest
+import grass.script as gs
+
+
+def _init_session(tmp_path, epsg_code):
+    """
+    Create a GRASS LOCATION and return its context manager.
+    """
+    project = tmp_path / f"r_latlong_{epsg_code}_project"
+    gs.create_project(project)
+    return gs.setup.init(project, env=os.environ.copy())
+
+
+@pytest.fixture
+def setup_maps(tmp_path):
+    """Set up a GRASS session and create test raster maps in EPSG:4326."""
+    with _init_session(tmp_path, "4326") as session:
+        gs.run_command(
+            "g.proj",
+            flags="c",
+            epsg="4326",
+            env=session.env,
+        )
+
+        # Define a 3×3 region in degrees
+        gs.run_command(
+            "g.region",
+            n=3,
+            s=0,
+            e=3,
+            w=0,
+            res=1,
+            env=session.env,
+        )
+
+        # Dummy raster map (values are irrelevant to r.latlong)
+        gs.mapcalc(
+            "custom_map = 1",
+            overwrite=True,
+            env=session.env,
+        )
+
+        yield session
+
+
+def clean_output(output):
+    """Normalize output by stripping whitespace from each line."""
+    return "\n".join([line.strip() for line in output.strip().splitlines()])
+
+
+def test_latlong_lat(setup_maps):
+    """Test default r.latlong output (latitude)."""
+    session = setup_maps
+
+    gs.run_command(
+        "r.latlong",
+        input="custom_map",
+        output="latlong_output",
+        env=session.env,
+    )
+
+    ascii_output = gs.read_command(
+        "r.out.ascii",
+        input="latlong_output",
+        env=session.env,
+    )
+    ascii_clean = clean_output(ascii_output)
+
+    expected_output = """north: 3N
+south: 0
+east: 3E
+west: 0
+rows: 3
+cols: 3
+3 3 3
+2 2 2
+1 1 1"""
+
+    assert ascii_clean == expected_output
+
+
+def test_l_flag(setup_maps):
+    """Test -l (longitude) flag output."""
+    session = setup_maps
+
+    gs.run_command(
+        "r.latlong",
+        input="custom_map",
+        output="latlong_output",
+        flags="l",
+        env=session.env,
+    )
+
+    ascii_output = gs.read_command(
+        "r.out.ascii",
+        input="latlong_output",
+        env=session.env,
+    )
+    ascii_clean = clean_output(ascii_output)
+
+    expected_output = """north: 3N
+south: 0
+east: 3E
+west: 0
+rows: 3
+cols: 3
+0 1 2
+0 1 2
+0 1 2"""
+
+    assert ascii_clean == expected_output
+
+
+def test_latlong_projected_epsg_3358(tmp_path):
+    """
+    test r.latlong in a projected CRS (EPSG:3358),
+    verify lat/long outputs stay within valid degree ranges.
+    """
+    with _init_session(tmp_path, "3358") as session:
+        gs.run_command(
+            "g.proj",
+            flags="c",
+            epsg="3358",
+            env=session.env,
+        )
+
+        gs.run_command(
+            "g.region",
+            n=3,
+            s=0,
+            e=3,
+            w=0,
+            res=1,
+            env=session.env,
+        )
+
+        gs.mapcalc(
+            "custom_map = 1",
+            overwrite=True,
+            env=session.env,
+        )
+
+        # Test latitude output
+        gs.run_command(
+            "r.latlong",
+            input="custom_map",
+            output="latlong_proj",
+            env=session.env,
+        )
+        info = gs.parse_command(
+            "r.info",
+            flags="r",  # range: to get min/max
+            map="latlong_proj",
+            env=session.env,
+        )
+        lat_min, lat_max = float(info["min"]), float(info["max"])
+        assert -90.0 <= lat_min < lat_max <= 90.0
+
+        # Test longitude output
+        gs.run_command(
+            "r.latlong",
+            input="custom_map",
+            output="lon_proj",
+            flags="l",
+            env=session.env,
+        )
+        info_lon = gs.parse_command(
+            "r.info",
+            flags="r",
+            map="lon_proj",
+            env=session.env,
+        )
+        lon_min, lon_max = float(info_lon["min"]), float(info_lon["max"])
+        assert -180.0 <= lon_min < lon_max <= 180.0