1 files changed, 42 insertions, 0 deletions
diff --git a/testing/mozharness/test/test_mozilla_release.py b/testing/mozharness/test/test_mozilla_release.py
new file mode 100644
index 000000000..adbe322c4
--- /dev/null
+++ b/testing/mozharness/test/test_mozilla_release.py
@@ -0,0 +1,42 @@
+import unittest
+from mozharness.mozilla.release import get_previous_version
+
+
+class TestGetPreviousVersion(unittest.TestCase):
+    def testESR(self):
+        self.assertEquals(
+            '31.5.3esr',
+            get_previous_version('31.6.0esr',
+                                 ['31.5.3esr', '31.5.2esr', '31.4.0esr']))
+
+    def testReleaseBuild1(self):
+        self.assertEquals(
+            '36.0.4',
+            get_previous_version('37.0', ['36.0.4', '36.0.1', '35.0.1']))
+
+    def testReleaseBuild2(self):
+        self.assertEquals(
+            '36.0.4',
+            get_previous_version('37.0',
+                                 ['37.0', '36.0.4', '36.0.1', '35.0.1']))
+
+    def testBetaMidCycle(self):
+        self.assertEquals(
+            '37.0b4',
+            get_previous_version('37.0b5', ['37.0b4', '37.0b3']))
+
+    def testBetaEarlyCycle(self):
+        # 37.0 is the RC build
+        self.assertEquals(
+            '38.0b1',
+            get_previous_version('38.0b2', ['38.0b1', '37.0']))
+
+    def testBetaFirstInCycle(self):
+        self.assertEquals(
+            '37.0',
+            get_previous_version('38.0b1', ['37.0', '37.0b7']))
+
+    def testTwoDots(self):
+        self.assertEquals(
+            '37.1.0',
+            get_previous_version('38.0b1', ['37.1.0', '36.0']))