diff --git a/src/access_nri_intake/catalog/manager.py b/src/access_nri_intake/catalog/manager.py
index 89424c0..049d2a9 100644
--- a/src/access_nri_intake/catalog/manager.py
+++ b/src/access_nri_intake/catalog/manager.py
@@ -43,13 +43,13 @@ def __init__(self, path):
 
         self.path = path
 
-        mode = "a" if os.path.exists(path) else "w"
+        self.mode = "a" if os.path.exists(path) else "w"
 
         self.dfcat = DfFileCatalog(
             path=self.path,
             yaml_column=YAML_COLUMN,
             name_column=NAME_COLUMN,
-            mode=mode,
+            mode=self.mode,
             columns_with_iterables=COLUMNS_WITH_ITERABLES,
         )
 
@@ -69,29 +69,29 @@ def build_esm(
         **kwargs,
     ):
         """
-        Build an intake-esm catalog
+        Build an Intake-ESM datastore
 
         Parameters
         ----------
         name: str
-            The name of the catalog
+            The name of the Intake-ESM datastore
         description: str
-            Description of the contents of the catalog
-        builder: subclass of :py:class:`access_nri_catalog.esmcat.BaseBuilder`
-            The builder to use to build the intake-esm catalog
+            Description of the contents of the Intake-ESM datastore
+        builder: subclass of :py:class:`access_nri_intake.source.builders.BaseBuilder`
+            The builder to use to build the Intake-ESM datastore
         path: str or list of str
-            Path or list of paths to crawl for assets/files to add to the catalog.
-        translator: :py:class:`~access_nri_catalog.metacat.translators.DefaultTranslator`
-            An instance of the :py:class:`~access_nri_catalog.metacat.translators.DefaultTranslator` class
-            for translating info in the intake-esm catalog into intake-dataframe-catalog column metadata.
-            Defaults to access_nri_catalog.metacat.translators.DefaultTranslator.
+            Path or list of paths to crawl for assets/files to add to the Intake-ESM datastore.
+        translator: :py:class:`~access_nri_intake.catalog.translators.DefaultTranslator`
+            An instance of the :py:class:`~access_nri_intake.catalog.translators.DefaultTranslator` class
+            for translating info in the Intake-ESM datastore into intake-dataframe-catalog column metadata.
+            Defaults to access_nri_intake.catalog.translators.DefaultTranslator.
         metadata: dict, optional
             Additional info to store in the intake cat.metadata attribute. This info will be available
-            to the translator and to users of the catalog
+            to the translator and to users of the Intake-ESM datastore
         directory: str
-            The directory to save the catalog to. If None, use the current directory
+            The directory to save the Intake-ESM datastore to. If None, use the current directory
         overwrite: bool, optional
-            Whether to overwrite any existing catalog(s) with the same name
+            Whether to overwrite any existing entries in the catalog with the same name
         kwargs: dict
             Additional kwargs to pass to the builder
         """
@@ -102,7 +102,7 @@ def build_esm(
         if os.path.isfile(json_file):
             if not overwrite:
                 raise CatalogManagerError(
-                    f"A catalog already exists for {name}. To overwrite, "
+                    f"An Intake-ESM datastore already exists for {name}. To overwrite, "
                     "pass `overwrite=True` to CatalogBuilder.build"
                 )
 
diff --git a/tests/test_manager.py b/tests/test_manager.py
new file mode 100644
index 0000000..ae44e0b
--- /dev/null
+++ b/tests/test_manager.py
@@ -0,0 +1,130 @@
+# Copyright 2023 ACCESS-NRI and contributors. See the top-level COPYRIGHT file for details.
+# SPDX-License-Identifier: Apache-2.0
+
+import pytest
+
+from access_nri_intake.catalog.manager import CatalogManager, CatalogManagerError
+from access_nri_intake.catalog.translators import (
+    Cmip5Translator,
+    Cmip6Translator,
+    EraiTranslator,
+)
+from access_nri_intake.source.builders import (
+    AccessCm2Builder,
+    AccessEsm15Builder,
+    AccessOm2Builder,
+)
+
+
+def test_CatalogManager_init(tmp_path):
+    """Test that CatalogManager initialising correctly"""
+    path = str(tmp_path / "cat.csv")
+
+    cat = CatalogManager(path)
+    assert cat.mode == "w"
+    assert hasattr(cat, "dfcat")
+
+
+@pytest.mark.parametrize(
+    "builder, basedir, kwargs",
+    [
+        (AccessOm2Builder, "access-om2", {}),
+        (AccessCm2Builder, "access-cm2/by578", {"ensemble": False}),
+        (AccessEsm15Builder, "access-esm1-5", {"ensemble": False}),
+    ],
+)
+def test_CatalogManager_build_esm(tmp_path, test_data, builder, basedir, kwargs):
+    """Test building and adding an Intake-ESM datastore"""
+    path = str(tmp_path / "cat.csv")
+    cat = CatalogManager(path)
+
+    args = dict(
+        name="test",
+        description="test",
+        builder=builder,
+        path=str(test_data / basedir),
+        metadata=dict(
+            model=[
+                basedir,
+            ]
+        ),
+        directory=str(tmp_path),
+        **kwargs,
+    )
+    cat.build_esm(**args).add()
+
+    # Try to rebuild without setting overwrite
+    with pytest.raises(CatalogManagerError) as excinfo:
+        cat.build_esm(**args)
+    assert "An Intake-ESM datastore already exists" in str(excinfo.value)
+
+    # Overwrite
+    cat.build_esm(**args, overwrite=True).add()
+
+    cat = CatalogManager(path)
+    assert cat.mode == "a"
+
+
+@pytest.mark.parametrize(
+    "translator, datastore, metadata",
+    [
+        (Cmip5Translator, "cmip5-al33.json", {}),
+        (Cmip6Translator, "cmip6-oi10.json", {}),
+        (EraiTranslator, "erai.json", {"model": ["ERA-Interim"]}),
+    ],
+)
+def test_CatalogManager_load(tmp_path, test_data, translator, datastore, metadata):
+    """Test loading and adding an Intake-ESM datastore"""
+    path = str(tmp_path / "cat.csv")
+    cat = CatalogManager(path)
+
+    args = dict(
+        name="test",
+        description="test",
+        path=str(test_data / f"esm_datastore/{datastore}"),
+        translator=translator,
+        metadata=metadata,
+    )
+    cat.load(**args).add()
+
+    cat = CatalogManager(path)
+    assert cat.mode == "a"
+
+
+def test_CatalogManager_all(tmp_path, test_data):
+    """Test adding multiple sources"""
+    path = str(tmp_path / "cat.csv")
+    cat = CatalogManager(path)
+
+    # Load source
+    load_args = dict(
+        name="cmip5-al33",
+        description="cmip5-al33",
+        path=str(test_data / "esm_datastore/cmip5-al33.json"),
+        translator=Cmip5Translator,
+    )
+    cat.load(
+        **load_args,
+    ).add()
+
+    # Build source
+    cat.build_esm(
+        name="access-om2",
+        description="access-om2",
+        builder=AccessOm2Builder,
+        path=str(test_data / "access-om2"),
+        metadata=dict(
+            model=[
+                "ACCESS-OM2",
+            ]
+        ),
+        directory=str(tmp_path),
+    ).add()
+
+    assert len(cat.dfcat) == 2
+
+    # Check that entry with same name overwrites correctly
+    cat.load(
+        **load_args,
+    ).add()
+    assert len(cat.dfcat) == 2