--- a/toolkit/components/telemetry/moz.build
+++ b/toolkit/components/telemetry/moz.build
@@ -96,16 +96,20 @@ EXTRA_JS_MODULES += [
     'ThirdPartyCookieProbe.jsm',
     'UITelemetry.jsm',
 ]
 
 TESTING_JS_MODULES += [
   'tests/unit/TelemetryArchiveTesting.jsm',
 ]
 
+PYTHON_UNITTEST_MANIFESTS += [
+    'tests/python/python.ini',
+]
+
 GENERATED_FILES = [
     'TelemetryEventData.h',
     'TelemetryEventEnums.h',
     'TelemetryHistogramData.inc',
     'TelemetryHistogramEnums.h',
     'TelemetryProcessData.h',
     'TelemetryProcessEnums.h',
     'TelemetryScalarData.h',

new file mode 100644
--- /dev/null
+++ b/toolkit/components/telemetry/tests/python/python.ini
@@ -0,0 +1,1 @@
+[test_histogramtools_non_strict.py]

new file mode 100644
--- /dev/null
+++ b/toolkit/components/telemetry/tests/python/test_histogramtools_non_strict.py
@@ -0,0 +1,78 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.import json
+
+import json
+import mozunit
+import sys
+import unittest
+from os import path
+
+TELEMETRY_ROOT_PATH = path.abspath(path.join(path.dirname(__file__), path.pardir, path.pardir))
+sys.path.append(TELEMETRY_ROOT_PATH)
+import histogram_tools   # noqa: E402
+
+
+def load_histogram(histograms):
+    """Parse the passed Histogram and return a dictionary mapping histogram
+    names to histogram parameters.
+
+    :param histogram: Histogram as a python dictionary
+    :returns: Parsed Histogram dictionary mapping histogram names to histogram parameters
+    """
+    def hook(ps):
+        return histogram_tools.load_histograms_into_dict(ps, strict_type_checks=False)
+    return json.loads(json.dumps(histograms), object_pairs_hook=hook)
+
+
+class TestParser(unittest.TestCase):
+    def test_unknown_field(self):
+        SAMPLE_HISTOGRAM = {
+            "A11Y_INSTANTIATED_FLAG": {
+                "record_in_processes": ["main", "content"],
+                "expires_in_version": "never",
+                "kind": "flag",
+                "description": "has accessibility support been instantiated",
+                "new_field": "Its a new field"
+                }}
+        histograms = load_histogram(SAMPLE_HISTOGRAM)
+
+        hist = histogram_tools.Histogram('A11Y_INSTANTIATED_FLAG',
+                                         histograms['A11Y_INSTANTIATED_FLAG'],
+                                         strict_type_checks=False)
+        self.assertEqual(hist.expiration(), 'never')
+        self.assertEqual(hist.kind(), 'flag')
+        self.assertEqual(hist.record_in_processes(), ["main", "content"])
+
+    def test_non_numeric_expressions(self):
+        SAMPLE_HISTOGRAM = {
+            "TEST_NON_NUMERIC_HISTOGRAM": {
+                "kind": "linear",
+                "description": "sample",
+                "n_buckets": "JS::gcreason::NUM_TELEMETRY_REASONS",
+                "high": "mozilla::StartupTimeline::MAX_EVENT_ID"
+                }}
+
+        histograms = load_histogram(SAMPLE_HISTOGRAM)
+        hist = histogram_tools.Histogram('TEST_NON_NUMERIC_HISTOGRAM',
+                                         histograms['TEST_NON_NUMERIC_HISTOGRAM'],
+                                         strict_type_checks=False)
+
+        # expected values come off histogram_tools.py
+        self.assertEqual(hist.n_buckets(), 101)
+        self.assertEqual(hist.high(), 12)
+
+    def test_current_histogram(self):
+        HISTOGRAMS_PATH = path.join(TELEMETRY_ROOT_PATH, "Histograms.json")
+        all_histograms = list(histogram_tools.from_files([HISTOGRAMS_PATH],
+                                                         strict_type_checks=False))
+        test_histogram = [i for i in all_histograms if i.name() == 'TELEMETRY_TEST_FLAG'][0]
+
+        self.assertEqual(test_histogram.expiration(), 'never')
+        self.assertEqual(test_histogram.kind(), 'flag')
+        self.assertEqual(test_histogram.record_in_processes(), ["main", "content"])
+        self.assertEqual(test_histogram.keyed(), False)
+
+
+if __name__ == '__main__':
+    mozunit.main()