diff --git a/src/__tests__/if-run/builtins/group-by.test.ts b/src/__tests__/if-run/builtins/group-by.test.ts
deleted file mode 100644
index b59da6836..000000000
--- a/src/__tests__/if-run/builtins/group-by.test.ts
+++ /dev/null
@@ -1,177 +0,0 @@
-import {ERRORS} from '@grnsft/if-core/utils';
-
-import {GroupBy} from '../../../if-run/builtins/group-by';
-
-import {STRINGS} from '../../../if-run/config';
-
-const {InvalidGroupingError, InputValidationError, GlobalConfigError} = ERRORS;
-const {MISSING_GLOBAL_CONFIG, INVALID_GROUP_BY} = STRINGS;
-
-describe('builtins/group-by: ', () => {
-  describe('GroupBy: ', () => {
-    const plugin = GroupBy();
-
-    describe('init GroupBy: ', () => {
-      it('initalizes object with properties.', async () => {
-        expect(plugin).toHaveProperty('metadata');
-        expect(plugin).toHaveProperty('execute');
-      });
-    });
-
-    describe('execute(): ', () => {
-      it('groups inputs correctly.', () => {
-        const inputs = [
-          {
-            timestamp: '2023-07-06T00:00',
-            region: 'uk-west',
-            'cloud/instance-type': 'A1',
-          },
-          {
-            timestamp: '2023-07-06T05:00',
-            region: 'uk-west',
-            'cloud/instance-type': 'A1',
-          },
-          {
-            timestamp: '2023-07-06T10:00',
-            region: 'uk-west',
-            'cloud/instance-type': 'A1',
-          },
-        ];
-        const config = {
-          group: ['region', 'cloud/instance-type'],
-        };
-
-        const expectedOutput = {
-          'uk-west': {
-            children: {
-              A1: {
-                inputs: [
-                  {
-                    'cloud/instance-type': 'A1',
-                    region: 'uk-west',
-                    timestamp: '2023-07-06T00:00',
-                  },
-                  {
-                    'cloud/instance-type': 'A1',
-                    region: 'uk-west',
-                    timestamp: '2023-07-06T05:00',
-                  },
-                  {
-                    'cloud/instance-type': 'A1',
-                    region: 'uk-west',
-                    timestamp: '2023-07-06T10:00',
-                  },
-                ],
-              },
-            },
-          },
-        };
-
-        const result = plugin.execute(inputs, config);
-        expect(result).toEqual(expectedOutput);
-      });
-
-      it('throws an error when config is not provided.', () => {
-        const inputs = [
-          {
-            timestamp: '2023-07-06T00:00',
-            region: 'uk-west',
-            'cloud/instance-type': 'A1',
-          },
-          {
-            timestamp: '2023-07-06T05:00',
-            region: 'uk-west',
-            'cloud/instance-type': 'A1',
-          },
-          {
-            timestamp: '2023-07-06T10:00',
-            region: 'uk-west',
-            'cloud/instance-type': 'A1',
-          },
-        ];
-
-        const config = undefined;
-
-        expect.assertions(2);
-        try {
-          plugin.execute(inputs, config!);
-        } catch (error) {
-          expect(error).toBeInstanceOf(GlobalConfigError);
-          expect(error).toEqual(new GlobalConfigError(MISSING_GLOBAL_CONFIG));
-        }
-      });
-
-      it('throws an error if `group` is an empty array.', () => {
-        const inputs = [
-          {
-            timestamp: '2023-07-06T00:00',
-            'cloud/instance-type': 'A1',
-          },
-          {
-            timestamp: '2023-07-06T05:00',
-            region: 'uk-west',
-            'cloud/instance-type': 'A1',
-          },
-          {
-            timestamp: '2023-07-06T10:00',
-            region: 'uk-west',
-            'cloud/instance-type': 'A1',
-          },
-        ];
-        const config = {
-          group: ['region', 'cloud/instance-type'],
-        };
-
-        expect.assertions(2);
-        try {
-          plugin.execute(inputs, config);
-        } catch (error) {
-          expect(error).toBeInstanceOf(InvalidGroupingError);
-          expect(error).toEqual(
-            new InvalidGroupingError('Invalid group region.')
-          );
-        }
-      });
-
-      it('throws an error if group type is missing from the input.', () => {
-        const inputs = [
-          {timestamp: 1, region: 'uk-west', 'cloud/instance-type': 'A1'},
-        ];
-        const config = {
-          group: [],
-        };
-
-        expect.assertions(2);
-        try {
-          plugin.execute(inputs, config);
-        } catch (error) {
-          expect(error).toBeInstanceOf(InputValidationError);
-          expect(error).toEqual(
-            new InputValidationError(
-              '"group" parameter is array must contain at least 1 element(s). Error code: too_small.'
-            )
-          );
-        }
-      });
-
-      it('throws an error if input does not have required group type.', () => {
-        const inputs = [
-          {timestamp: 1, region: 'uk-west', 'cloud/instance-type': 'A1'},
-        ];
-        const config = {
-          group: ['region', 'cloud/instance-type', 'unknown'],
-        };
-
-        expect.assertions(2);
-        try {
-          plugin.execute(inputs, config);
-        } catch (error) {
-          expect(error).toBeInstanceOf(InvalidGroupingError);
-          expect(error).toEqual(
-            new InvalidGroupingError(INVALID_GROUP_BY(config.group[2]))
-          );
-        }
-      });
-    });
-  });
-});
diff --git a/src/__tests__/if-run/lib/regroup.test.ts b/src/__tests__/if-run/lib/regroup.test.ts
new file mode 100644
index 000000000..9f0b373ff
--- /dev/null
+++ b/src/__tests__/if-run/lib/regroup.test.ts
@@ -0,0 +1,161 @@
+import {ERRORS} from '@grnsft/if-core/utils';
+
+import {STRINGS} from '../../../if-run/config';
+import {Regroup} from '../../../if-run/lib/regroup';
+
+const {InvalidGroupingError, InputValidationError} = ERRORS;
+const {INVALID_GROUP_KEY} = STRINGS;
+
+describe('lib/regroup: ', () => {
+  describe('Regroup: ', () => {
+    it('groups inputs correctly.', () => {
+      const inputs = [
+        {
+          timestamp: '2023-07-06T00:00',
+          region: 'uk-west',
+          'cloud/instance-type': 'A1',
+        },
+        {
+          timestamp: '2023-07-06T05:00',
+          region: 'uk-west',
+          'cloud/instance-type': 'A1',
+        },
+        {
+          timestamp: '2023-07-06T10:00',
+          region: 'uk-west',
+          'cloud/instance-type': 'A1',
+        },
+      ];
+      const groups = ['region', 'cloud/instance-type'];
+
+      const expectedOutput = {
+        'uk-west': {
+          children: {
+            A1: {
+              inputs: [
+                {
+                  'cloud/instance-type': 'A1',
+                  region: 'uk-west',
+                  timestamp: '2023-07-06T00:00',
+                },
+                {
+                  'cloud/instance-type': 'A1',
+                  region: 'uk-west',
+                  timestamp: '2023-07-06T05:00',
+                },
+                {
+                  'cloud/instance-type': 'A1',
+                  region: 'uk-west',
+                  timestamp: '2023-07-06T10:00',
+                },
+              ],
+            },
+          },
+        },
+      };
+
+      const result = Regroup(inputs, groups);
+      expect(result).toEqual(expectedOutput);
+    });
+
+    it('throws an error when groups is not provided.', () => {
+      const inputs = [
+        {
+          timestamp: '2023-07-06T00:00',
+          region: 'uk-west',
+          'cloud/instance-type': 'A1',
+        },
+        {
+          timestamp: '2023-07-06T05:00',
+          region: 'uk-west',
+          'cloud/instance-type': 'A1',
+        },
+        {
+          timestamp: '2023-07-06T10:00',
+          region: 'uk-west',
+          'cloud/instance-type': 'A1',
+        },
+      ];
+
+      const groups = undefined;
+
+      expect.assertions(2);
+      try {
+        Regroup(inputs, groups!);
+      } catch (error) {
+        expect(error).toBeInstanceOf(InputValidationError);
+        expect(error).toEqual(
+          new InputValidationError(
+            '"groups" parameter is required. Error code: invalid_type.'
+          )
+        );
+      }
+    });
+
+    it('throws an error if `group` is an empty array.', () => {
+      const inputs = [
+        {
+          timestamp: '2023-07-06T00:00',
+          'cloud/instance-type': 'A1',
+        },
+        {
+          timestamp: '2023-07-06T05:00',
+          region: 'uk-west',
+          'cloud/instance-type': 'A1',
+        },
+        {
+          timestamp: '2023-07-06T10:00',
+          region: 'uk-west',
+          'cloud/instance-type': 'A1',
+        },
+      ];
+      const groups = ['region', 'cloud/instance-type'];
+
+      expect.assertions(2);
+      try {
+        Regroup(inputs, groups);
+      } catch (error) {
+        expect(error).toBeInstanceOf(InvalidGroupingError);
+        expect(error).toEqual(
+          new InvalidGroupingError('Invalid group region.')
+        );
+      }
+    });
+
+    it('throws an error if group type is missing from the input.', () => {
+      const inputs = [
+        {timestamp: 1, region: 'uk-west', 'cloud/instance-type': 'A1'},
+      ];
+      const groups: any[] = [];
+
+      expect.assertions(2);
+      try {
+        Regroup(inputs, groups);
+      } catch (error) {
+        expect(error).toBeInstanceOf(InputValidationError);
+        expect(error).toEqual(
+          new InputValidationError(
+            '"groups" parameter is regroup phase is not an array or should contain at least one key.. Error code: too_small.'
+          )
+        );
+      }
+    });
+
+    it('throws an error if input does not have required group type.', () => {
+      const inputs = [
+        {timestamp: 1, region: 'uk-west', 'cloud/instance-type': 'A1'},
+      ];
+      const groups = ['region', 'cloud/instance-type', 'unknown'];
+
+      expect.assertions(2);
+      try {
+        Regroup(inputs, groups);
+      } catch (error) {
+        expect(error).toBeInstanceOf(InvalidGroupingError);
+        expect(error).toEqual(
+          new InvalidGroupingError(INVALID_GROUP_KEY(groups[2]))
+        );
+      }
+    });
+  });
+});