diff --git a/.github/workflows/style.yml b/.github/workflows/style.yml
index 0dbb6e269..cf14b5b6a 100644
--- a/.github/workflows/style.yml
+++ b/.github/workflows/style.yml
@@ -10,10 +10,14 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: '3.12'
 
     - name: Install dependencies
       run: |
-        sudo pip install cmake-format black
+        pip install cmake-format clang-format black
 
     - name: Clang Format
       run: ./script/clang-format --check
diff --git a/lib/include/resdata/rd_file.hpp b/lib/include/resdata/rd_file.hpp
index 9f073174a..d60e71dc6 100644
--- a/lib/include/resdata/rd_file.hpp
+++ b/lib/include/resdata/rd_file.hpp
@@ -16,9 +16,8 @@ extern "C" {
 #include <resdata/rd_type.hpp>
 
 #define RD_FILE_FLAGS_ENUM_DEFS                                                \
-    {.value = 1, .name = "RD_FILE_CLOSE_STREAM"}, {                            \
-        .value = 2, .name = "RD_FILE_WRITABLE"                                 \
-    }
+    {.value = 1, .name = "RD_FILE_CLOSE_STREAM"},                              \
+        {.value = 2, .name = "RD_FILE_WRITABLE"}
 #define RD_FILE_FLAGS_ENUM_SIZE 2
 
 typedef struct rd_file_struct rd_file_type;
diff --git a/lib/include/resdata/rd_grid.hpp b/lib/include/resdata/rd_grid.hpp
index fe15fdbf5..690fbcfbc 100644
--- a/lib/include/resdata/rd_grid.hpp
+++ b/lib/include/resdata/rd_grid.hpp
@@ -16,7 +16,7 @@ extern "C" {
 #endif
 
 #define RD_GRID_COORD_SIZE(nx, ny) (((nx) + 1) * ((ny) + 1) * 6)
-#define RD_GRID_ZCORN_SIZE(nx, ny, nz) (((nx) * (ny) * (nz)*8))
+#define RD_GRID_ZCORN_SIZE(nx, ny, nz) (((nx) * (ny) * (nz) * 8))
 
 #define RD_GRID_GLOBAL_GRID "Global" // used as key in hash tables over grids.
 #define RD_GRID_MAINGRID_LGR_NR 0
diff --git a/lib/include/resdata/rd_type.hpp b/lib/include/resdata/rd_type.hpp
index fa6c7bcf4..57bbbd2b7 100644
--- a/lib/include/resdata/rd_type.hpp
+++ b/lib/include/resdata/rd_type.hpp
@@ -39,9 +39,8 @@ typedef enum {
         {.value = 2, .name = "RD_DOUBLE_TYPE"},                                \
         {.value = 3, .name = "RD_INT_TYPE"},                                   \
         {.value = 4, .name = "RD_BOOL_TYPE"},                                  \
-        {.value = 5, .name = "RD_MESS_TYPE"}, {                                \
-        .value = 7, .name = "RD_STRING_TYPE"                                   \
-    }
+        {.value = 5, .name = "RD_MESS_TYPE"},                                  \
+        {.value = 7, .name = "RD_STRING_TYPE"}
 
 /*
   Character data in restart format files comes as an array of fixed-length
@@ -67,20 +66,15 @@ struct rd_type_struct {
     rd_data_type { RD_DOUBLE_TYPE, sizeof(double) }
 #define RD_BOOL                                                                \
     rd_data_type { RD_BOOL_TYPE, sizeof(bool) }
-#define RD_CHAR                                                                \
-    rd_data_type { RD_CHAR_TYPE, RD_STRING8_LENGTH + 1 }
-#define RD_MESS                                                                \
-    rd_data_type { RD_MESS_TYPE, 0 }
-#define RD_STRING(size)                                                        \
-    rd_data_type { RD_STRING_TYPE, (size) + 1 }
+#define RD_CHAR rd_data_type{RD_CHAR_TYPE, RD_STRING8_LENGTH + 1}
+#define RD_MESS rd_data_type{RD_MESS_TYPE, 0}
+#define RD_STRING(size) rd_data_type{RD_STRING_TYPE, (size) + 1}
 }
 
 #else
 
 #define RD_CHAR                                                                \
-    (rd_data_type) {                                                           \
-        .type = RD_CHAR_TYPE, .element_size = RD_STRING8_LENGTH + 1            \
-    }
+    (rd_data_type){.type = RD_CHAR_TYPE, .element_size = RD_STRING8_LENGTH + 1}
 #define RD_INT                                                                 \
     (rd_data_type) { .type = RD_INT_TYPE, .element_size = sizeof(int) }
 #define RD_FLOAT                                                               \
@@ -89,10 +83,9 @@ struct rd_type_struct {
     (rd_data_type) { .type = RD_DOUBLE_TYPE, .element_size = sizeof(double) }
 #define RD_BOOL                                                                \
     (rd_data_type) { .type = RD_BOOL_TYPE, .element_size = sizeof(bool) }
-#define RD_MESS                                                                \
-    (rd_data_type) { .type = RD_MESS_TYPE, .element_size = 0 }
+#define RD_MESS (rd_data_type){.type = RD_MESS_TYPE, .element_size = 0}
 #define RD_STRING(size)                                                        \
-    (rd_data_type) { .type = RD_STRING_TYPE, .element_size = (size) + 1 }
+    (rd_data_type){.type = RD_STRING_TYPE, .element_size = (size) + 1}
 
 #endif
 
diff --git a/lib/include/resdata/rd_units.hpp b/lib/include/resdata/rd_units.hpp
index 536bbcb05..1b4641024 100644
--- a/lib/include/resdata/rd_units.hpp
+++ b/lib/include/resdata/rd_units.hpp
@@ -6,8 +6,8 @@ extern "C" {
 #endif
 
 #define RD_UNITS_CUBIC(x) ((x) * (x) * (x))
-#define RD_UNITS_MILLI(x) ((x)*0.001)
-#define RD_UNITS_MEGA(x) ((x)*1000000)
+#define RD_UNITS_MILLI(x) ((x) * 0.001)
+#define RD_UNITS_MEGA(x) ((x) * 1000000)
 
 #define RD_UNITS_LENGTH_INCH 0.0254
 #define RD_UNITS_LENGTH_FEET 12 * RD_UNITS_LENGTH_INCH
diff --git a/lib/include/resdata/rd_util.hpp b/lib/include/resdata/rd_util.hpp
index 6fbc6fee6..870e5bd03 100644
--- a/lib/include/resdata/rd_util.hpp
+++ b/lib/include/resdata/rd_util.hpp
@@ -77,9 +77,8 @@ typedef enum {
 
 #define RD_PHASE_ENUM_DEFS                                                     \
     {.value = 1, .name = "RD_OIL_PHASE"},                                      \
-        {.value = 2, .name = "RD_GAS_PHASE"}, {                                \
-        .value = 4, .name = "RD_WATER_PHASE"                                   \
-    }
+        {.value = 2, .name = "RD_GAS_PHASE"},                                  \
+        {.value = 4, .name = "RD_WATER_PHASE"}
 #define RD_PHASE_ENUM_SIZE 3
 
 typedef enum {
diff --git a/lib/resdata/tests/rd_kw_fread.cpp b/lib/resdata/tests/rd_kw_fread.cpp
index 55af4d2e1..c4a3d538a 100644
--- a/lib/resdata/tests/rd_kw_fread.cpp
+++ b/lib/resdata/tests/rd_kw_fread.cpp
@@ -76,7 +76,9 @@ void test_kw_io_charlength() {
             fortio_fclose(f);
         }
 
-        { test_assert_false(util_file_exists("TEST1")); }
+        {
+            test_assert_false(util_file_exists("TEST1"));
+        }
 
         {
             FILE *file = util_fopen("TEST2", "w");
diff --git a/lib/util/util.cpp b/lib/util/util.cpp
index b720803aa..873e49a93 100644
--- a/lib/util/util.cpp
+++ b/lib/util/util.cpp
@@ -189,8 +189,8 @@ void util_endian_flip_vector(void *data, int element_size, int elements) {
 }
 
 #ifndef S_ISDIR
-#define S_ISDIR(m) (((m)&S_IFMT) == S_IFDIR)
-#define S_ISREG(m) (((m)&S_IFMT) == S_IFREG)
+#define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
+#define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
 #endif
 
 static bool EOL_CHAR(char c) {
diff --git a/python/resdata/grid/faults/fault_block.py b/python/resdata/grid/faults/fault_block.py
index a74a4c17d..787d61037 100644
--- a/python/resdata/grid/faults/fault_block.py
+++ b/python/resdata/grid/faults/fault_block.py
@@ -139,7 +139,7 @@ def contains_polyline(self, polyline):
         """
         Will return true if at least one point from the polyline is inside the block.
         """
-        edge_polyline = self.getEdgePolygon()
+        edge_polyline = self.get_edge_polygon()
         for p in polyline:
             if GeometryTools.pointInPolygon(p, edge_polyline):
                 return True
diff --git a/python/resdata/grid/faults/fault_block_layer.py b/python/resdata/grid/faults/fault_block_layer.py
index 3176456a9..79be79bf3 100644
--- a/python/resdata/grid/faults/fault_block_layer.py
+++ b/python/resdata/grid/faults/fault_block_layer.py
@@ -199,7 +199,7 @@ def add_fault_link(self, fault1, fault2):
 
     def join_faults(self, fault1, fault2):
         if not fault1.intersectsFault(fault2, self.getK()):
-            layer = self.getGeoLayer()
+            layer = self.get_geo_layer()
             try:
                 layer.addIJBarrier(Fault.joinFaults(fault1, fault2, self.getK()))
             except ValueError:
diff --git a/python/resdata/grid/faults/fault_segments.py b/python/resdata/grid/faults/fault_segments.py
index b5ff6e91a..90c328ce2 100644
--- a/python/resdata/grid/faults/fault_segments.py
+++ b/python/resdata/grid/faults/fault_segments.py
@@ -68,7 +68,7 @@ def __str__(self):
         return self.__segment_map.__str__()
 
     def verify(self):
-        for C, count in self.__count_map.iteritems():
+        for C, count in self.__count_map.items():
             if count > 0:
                 d = self.__segment_map[C]
                 if len(d) != count:
@@ -135,7 +135,7 @@ def pop_next(self, segment):
 
     def print_content(self):
         for d in self.__segment_map.values():
-            for C, S in d.iteritems():
+            for C, S in d.items():
                 print(S)
 
 
diff --git a/python/resdata/grid/faults/layer.py b/python/resdata/grid/faults/layer.py
index eaf263f42..9e5f6e8da 100644
--- a/python/resdata/grid/faults/layer.py
+++ b/python/resdata/grid/faults/layer.py
@@ -179,8 +179,8 @@ def add_ij_barrier(self, ij_list):
         if len(ij_list) < 2:
             raise ValueError("Must have at least two (i,j) points")
 
-        nx = self.getNX()
-        ny = self.getNY()
+        nx = self.get_nx()
+        ny = self.get_ny()
         p1 = ij_list[0]
         i1, j1 = p1
         for p2 in ij_list[1:]:
diff --git a/python/tests/rd_tests/test_fault_blocks.py b/python/tests/rd_tests/test_fault_blocks.py
index 09c648e46..895af8711 100644
--- a/python/tests/rd_tests/test_fault_blocks.py
+++ b/python/tests/rd_tests/test_fault_blocks.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
-from unittest import skipIf
 import cwrap
+import pytest
 
 from resdata import ResDataType
 from resdata.resfile import ResdataKW
@@ -147,6 +147,7 @@ def test_neighbours2(self):
                 f.write("FAULTS\n")
                 f.write("'FY'   1   4   4   4   1   1  'Y'  /\n")
                 f.write("'FX'   4   4   1   8   1   1  'X'  /\n")
+                f.write("'FXX'   6   6   1   8   1   1  'X'  /\n")
                 f.write("/")
 
             faults = FaultCollection(grid, "faults.grdecl")
@@ -185,6 +186,10 @@ def test_neighbours2(self):
         nb = b1.getNeighbours()
         self.assertEqual(len(nb), 0)
 
+        layer.join_faults(faults["FX"], faults["FY"])
+        with pytest.raises(ValueError, match="Failed to join faults FXX and FY"):
+            layer.join_faults(faults["FXX"], faults["FY"])
+
     def test_neighbours3(self):
         nx = 8
         ny = 8
@@ -286,6 +291,9 @@ def test_fault_block_layer(self):
         polyline = Polyline(init_points=[(1.0, 0.0), (2.0, 1.0)])
         assert l1.contains_polyline(polyline)
 
+        polyline2 = Polyline(init_points=[(10.5, 1.0), (11, 5)])
+        assert not l1.contains_polyline(polyline2)
+
         with self.assertRaises(KeyError):
             l = layer.getBlock(66)
 
@@ -417,6 +425,11 @@ def test_internal_blocks(self):
             faults = FaultCollection(grid, "faults.grdecl")
 
         layer.loadKeyword(kw)
+        faulty_kw = ResdataKW("SOIL", 10000, ResDataType.RD_INT)
+        with pytest.raises(
+            ValueError, match="The fault block keyword had wrong type/size"
+        ):
+            layer.load_keyword(faulty_kw)
         layer.addFaultBarrier(faults["FX"])
         b1 = layer.getBlock(1)
         b2 = layer.getBlock(2)
diff --git a/python/tests/rd_tests/test_faults.py b/python/tests/rd_tests/test_faults.py
index 048e68054..f8a6ff3c6 100644
--- a/python/tests/rd_tests/test_faults.py
+++ b/python/tests/rd_tests/test_faults.py
@@ -12,6 +12,7 @@
     FaultLine,
     FaultSegment,
     FaultBlockLayer,
+    SegmentMap,
 )
 from resdata.util.test import TestAreaContext
 from resdata.geometry import Polyline, CPolyline
@@ -127,6 +128,36 @@ def test_faultLine_center(self):
         self.assertEqual(len(fl), 2)
         self.assertEqual(fl.center(), (0.50, 0.50))
 
+    def test_fault_segments(self):
+        S1 = FaultSegment(0, 10)
+        S2 = FaultSegment(10, 20)
+        S3 = FaultSegment(0, 10)
+        S4 = FaultSegment(10, 0)
+        S5 = FaultSegment(30, 40)
+        S6 = FaultSegment(50, 40)
+        assert S1 != S2
+        assert S1 == S3
+        assert S3 == S4
+        assert S1.joins(S2)
+        assert S2.joins(S4)
+        assert S1.joins(S4)
+        assert not S2.joins(S5)
+        assert not S5.joins(S2)
+        assert S6.joins(S5)
+
+    def test_segment_map(self):
+        S1 = FaultSegment(0, 10)
+        S2 = FaultSegment(10, 20)
+        S5 = FaultSegment(30, 40)
+        SM = SegmentMap()
+        SM.add_segment(S1)
+        SM.add_segment(S2)
+        assert len(SM) == 3
+        SM.verify()
+        SM.add_segment(S5)
+        assert len(SM) == 5
+        SM.print_content()
+
     def test_faultLine(self):
         fl = FaultLine(self.grid, 10)
         S1 = FaultSegment(0, 10)
diff --git a/python/tests/rd_tests/test_grdecl.py b/python/tests/rd_tests/test_grdecl.py
index f9e7c733a..cd77ef7bc 100644
--- a/python/tests/rd_tests/test_grdecl.py
+++ b/python/tests/rd_tests/test_grdecl.py
@@ -1,10 +1,12 @@
+import pytest
+
 from numpy import allclose
 
 import cwrap
 from resdata.resfile import ResdataKW
 
 
-def test_eclkw_read_grdecl(tmp_path):
+def test_resdatakw_read_grdecl(tmp_path):
     block_size = 10
     num_blocks = 5
     value = 0.15
@@ -17,6 +19,8 @@ def test_eclkw_read_grdecl(tmp_path):
     with cwrap.open(str(tmp_path / "test.grdecl")) as f:
         kw = ResdataKW.read_grdecl(f, "COORD")
         assert ResdataKW.fseek_grdecl(f, "COORD", True)
+        with pytest.raises(TypeError, match="Sorry keyword:TOOLONGAKW"):
+            ResdataKW.read_grdecl(f, "TOOLONGAKW")
 
     assert kw.get_name() == "COORD"
     assert len(kw.numpy_view()) == block_size * num_blocks
diff --git a/python/tests/rd_tests/test_grid.py b/python/tests/rd_tests/test_grid.py
index 4d8e734c1..8d1e6421e 100644
--- a/python/tests/rd_tests/test_grid.py
+++ b/python/tests/rd_tests/test_grid.py
@@ -2,9 +2,10 @@
 import os.path
 from unittest import skip
 import itertools
+import pytest
 
 import functools
-from numpy import linspace, allclose
+import numpy as np
 import cwrap
 
 from resdata.util.util import IntVector, DoubleVector
@@ -260,6 +261,13 @@ def test_dims(self):
 
         self.assertEqual(grid.getDims(), (10, 20, 30, 6000))
 
+    def test_global_index(self):
+        grid = GridGen.createRectangular((10, 20, 30), (1, 1, 1))
+        with pytest.raises(
+            IndexError, match=r"Invalid value global_index:7000  Range: \[0,6000\)"
+        ):
+            grid.get_active_index(global_index=7000)
+
     def test_load_column(self):
         column = DoubleVector(2 * 3 * 4)
         grid = GridGen.createRectangular((2, 3, 4), (1, 1, 1))
@@ -455,7 +463,18 @@ def test_create_3d_is_create_kw_inverse(self):
         numpy_3d = grid.create3D(kw1)
         kw2 = grid.create_kw(numpy_3d, "SWAT", False)
         self.assertEqual(kw2.name, "SWAT")
-        assert allclose(grid.create3D(kw2), numpy_3d)
+        assert np.allclose(grid.create3D(kw2), numpy_3d)
+
+    def test_create_kw(self):
+        rng = np.random.default_rng()
+        nx = 10
+        ny = 7
+        nz = 5
+        grid = GridGen.create_rectangular((nx, ny, nz), (1, 1, 1))
+        array1 = rng.integers(0, 100, size=(nx, ny, nz), dtype=np.int32)
+        array2 = rng.normal(10, 2, size=(nx, ny, nz))
+        _ = grid.create_kw(array1, "SWAT1", False)
+        _ = grid.create_kw(array2, "SWAT2", False)
 
     def test_create_3d_agrees_with_get_value(self):
         nx = 5
@@ -539,13 +558,13 @@ def test_unique_containment(self):
 
             (xmin, xmax), (ymin, ymax), (zmin, zmax) = getMinMaxValue(wgrid)
 
-            x_space = linspace(
+            x_space = np.linspace(
                 xmin - 1, xmax + 1, int(xmax - xmin + 2) * steps_per_unit + 1
             )
-            y_space = linspace(
+            y_space = np.linspace(
                 ymin - 1, ymax + 1, int(ymax - ymin + 2) * steps_per_unit + 1
             )
-            z_space = linspace(
+            z_space = np.linspace(
                 zmin - 1, zmax + 1, int(zmax - zmin + 2) * steps_per_unit + 1
             )
 
diff --git a/python/tests/rd_tests/test_rd_file.py b/python/tests/rd_tests/test_rd_file.py
index c4f08d270..ca649439b 100644
--- a/python/tests/rd_tests/test_rd_file.py
+++ b/python/tests/rd_tests/test_rd_file.py
@@ -247,6 +247,9 @@ def test_block_view(self):
 
             view = rd_file.blockView2(None, "DATA2", 0)
 
+            with pytest.raises(KeyError, match="The keyword:FAULTY is not in file"):
+                rd_file.block_view2("HEADER", "FAULTY", 0)
+
 
 def test_report_list(tmpdir):
     with tmpdir.as_cwd():
diff --git a/python/tests/rd_tests/test_rd_kw.py b/python/tests/rd_tests/test_rd_kw.py
index 4ff7b17e8..7adb45cef 100644
--- a/python/tests/rd_tests/test_rd_kw.py
+++ b/python/tests/rd_tests/test_rd_kw.py
@@ -1,4 +1,7 @@
 #!/usr/bin/env python
+
+import pytest
+
 import random
 import warnings
 import cwrap
@@ -622,6 +625,25 @@ def test_iadd():
 
     assert list(kw1) == list(kw2)
 
+    with pytest.raises(TypeError, match="Type mismatch"):
+        kw1 += "a"
+
+
+def test_imul():
+    kw1 = ResdataKW("KW1", 5, ResDataType.RD_INT)
+    for i in range(len(kw1)):
+        kw1[i] = 1
+    kw1 *= 10
+
+    assert list(kw1) == [10] * 5
+
+    with pytest.raises(TypeError, match="Type mismatch"):
+        kw1 *= 3.2
+
+    kw2 = ResdataKW("KW2", 5, ResDataType.RD_FLOAT)
+    with pytest.raises(TypeError, match="Only muliplication with scalar supported"):
+        kw2 *= "a"
+
 
 def test_get_ptr_data():
     assert ResdataKW("KW1", 10, ResDataType.RD_INT).get_data_ptr()
diff --git a/python/tests/rd_tests/test_rd_util.py b/python/tests/rd_tests/test_rd_util.py
index 7343abb10..39a41c790 100644
--- a/python/tests/rd_tests/test_rd_util.py
+++ b/python/tests/rd_tests/test_rd_util.py
@@ -13,7 +13,10 @@ def test_enums(self):
 
     def test_file_type(self):
         file_type, fmt, report = ResdataUtil.inspectExtension("CASE.X0078")
-        self.assertEqual(file_type, FileType.RESTART)
+        assert file_type == FileType.RESTART
+        file_type, fmt, report = ResdataUtil.inspectExtension("CASE.UNRST")
+        assert file_type == FileType.UNIFIED_RESTART
+        assert report == None
 
     def test_file_report_nr(self):
         report_nr = ResdataUtil.reportStep("CASE.X0080")
diff --git a/python/tests/rd_tests/test_region.py b/python/tests/rd_tests/test_region.py
index 2196d829b..840c70e74 100644
--- a/python/tests/rd_tests/test_region.py
+++ b/python/tests/rd_tests/test_region.py
@@ -24,6 +24,12 @@ def test_equal(self):
         with self.assertRaises(ValueError):
             region.select_equal(kw_float, 1)
 
+        with pytest.raises(
+            ValueError,
+            match="The select_equal method must have an integer valued keyword",
+        ):
+            region.deselect_equal(kw_float, 2)
+
     def test_sum(self):
         grid = GridGenerator.create_rectangular((10, 10, 1), (1, 1, 1))
         kw_mask = ResdataKW("INT", grid.getGlobalSize(), ResDataType.RD_INT)
@@ -220,6 +226,13 @@ def poro(grid):
     )
 
 
+@pytest.fixture
+def poro_int(grid):
+    return grid.create_kw(
+        np.ones((grid.nx, grid.ny, grid.nz), dtype=np.int32), "PORO", True
+    )
+
+
 def test_select_in_range(empty_region, active_region, poro):
     empty_region.select_in_range(poro, 0.9, 1.1)
     assert empty_region == active_region
@@ -464,6 +477,12 @@ def test_idiv_kw_full(full_region, poro):
     assert list(poro) == [1.0] * len(poro)
 
 
+def test_idiv_kw_int(full_region, poro_int):
+    poro_int += 1
+    full_region.idiv_kw(poro_int, 10)
+    assert list(poro_int) == [0] * len(poro_int)  # ???
+
+
 def test_mul_kw_full(full_region, poro):
     poro += 1.0
     poro.mul(poro, mask=full_region)