test(git): add test case for get tags functions

Author: Lee-W

tests/test_git.py

@@ -1,6 +1,12 @@
 from commitizen import git
 
 
+class FakeCommand:
+    def __init__(self, out=None, err=None):
+        self.out = out
+        self.err = err
+
+
 def test_git_object_eq():
     git_commit = git.GitCommit(
         rev="sha1-code", title="this is title", body="this is body"
@@ -9,3 +15,35 @@ def test_git_object_eq():
 
     assert git_commit == git_tag
     assert git_commit != "sha1-code"
+
+
+def test_get_tags(mocker):
+    tag_str = (
+        "v1.0.0---inner_delimiter---333---inner_delimiter---2020-01-20\n"
+        "v0.5.0---inner_delimiter---222---inner_delimiter---2020-01-17\n"
+        "v0.0.1---inner_delimiter---111---inner_delimiter---2020-01-17\n"
+    )
+    mocker.patch("commitizen.cmd.run", return_value=FakeCommand(out=tag_str))
+
+    git_tags = git.get_tags()
+    latest_git_tag = git_tags[0]
+    assert latest_git_tag.rev == "333"
+    assert latest_git_tag.name == "v1.0.0"
+    assert latest_git_tag.date == "2020-01-20"
+
+    mocker.patch(
+        "commitizen.cmd.run", return_value=FakeCommand(out="", err="No tag available")
+    )
+    assert git.get_tags() == []
+
+
+def test_get_tag_names(mocker):
+    tag_str = "v1.0.0\n" "v0.5.0\n" "v0.0.1\n"
+    mocker.patch("commitizen.cmd.run", return_value=FakeCommand(out=tag_str))
+
+    assert git.get_tag_names() == ["v1.0.0", "v0.5.0", "v0.0.1"]
+
+    mocker.patch(
+        "commitizen.cmd.run", return_value=FakeCommand(out="", err="No tag available")
+    )
+    assert git.get_tag_names() == []