Repository: getmoto/moto

Issue:
Cloudwatch metrics don't reject NaN values
# Steps to reproduce:

```
from moto import mock_cloudwatch
import boto3
from decimal import Decimal
from time import time

#with mock_cloudwatch():
boto3.client('cloudwatch').put_metric_data(
    Namespace='mynamespace',
    MetricData=[
        {
           'MetricName': 'mymetric',
            'Timestamp': int(time()), 
            'Value': Decimal('NaN'),
            'Unit': 'Count',
        }
    ]
)
```

# Expected Behavior

Without moto, with real boto, we get:

```
Traceback (most recent call last):
  File "cw-nan.py", line 7, in <module>
    boto3.client('cloudwatch').put_metric_data(
  File "/home/ec2-user/.local/lib/python3.8/site-packages/botocore/client.py", line 357, in _api_call
    return self._make_api_call(operation_name, kwargs)
  File "/home/ec2-user/.local/lib/python3.8/site-packages/botocore/client.py", line 676, in _make_api_call
    raise error_class(parsed_response, operation_name)
botocore.errorfactory.InvalidParameterValueException: An error occurred (InvalidParameterValue) when calling the PutMetricData operation: The value NaN for parameter MetricData.member.1.Value is invalid.
```

# Actual Behavior

boto call suceeds. `NaN` was put as a metric value.


Discussion:

Resolving patch:
diff --git a/moto/cloudwatch/models.py b/moto/cloudwatch/models.py
--- a/moto/cloudwatch/models.py
+++ b/moto/cloudwatch/models.py
@@ -438,6 +438,12 @@ def delete_alarms(self, alarm_names):
             self.alarms.pop(alarm_name, None)
 
     def put_metric_data(self, namespace, metric_data):
+        for i, metric in enumerate(metric_data):
+            if metric.get("Value") == "NaN":
+                raise InvalidParameterValue(
+                    f"The value NaN for parameter MetricData.member.{i + 1}.Value is invalid."
+                )
+
         for metric_member in metric_data:
             # Preserve "datetime" for get_metric_statistics comparisons
             timestamp = metric_member.get("Timestamp")


Test patch:
diff --git a/tests/test_cloudwatch/test_cloudwatch_alarms.py b/tests/test_cloudwatch/test_cloudwatch_alarms.py
new file mode 100644
--- /dev/null
+++ b/tests/test_cloudwatch/test_cloudwatch_alarms.py
@@ -0,0 +1,250 @@
+import boto3
+import sure  # noqa
+
+from moto import mock_cloudwatch
+from moto.core import ACCOUNT_ID
+
+
+@mock_cloudwatch
+def test_create_alarm():
+    region = "eu-west-1"
+    cloudwatch = boto3.client("cloudwatch", region)
+
+    name = "tester"
+    cloudwatch.put_metric_alarm(
+        AlarmActions=["arn:alarm"],
+        AlarmDescription="A test",
+        AlarmName=name,
+        ComparisonOperator="GreaterThanOrEqualToThreshold",
+        Dimensions=[{"Name": "InstanceId", "Value": "i-0123457"}],
+        EvaluationPeriods=5,
+        InsufficientDataActions=["arn:insufficient"],
+        Namespace="{0}_namespace".format(name),
+        MetricName="{0}_metric".format(name),
+        OKActions=["arn:ok"],
+        Period=60,
+        Statistic="Average",
+        Threshold=2,
+        Unit="Seconds",
+    )
+
+    alarms = cloudwatch.describe_alarms()["MetricAlarms"]
+    alarms.should.have.length_of(1)
+    alarm = alarms[0]
+    alarm.should.have.key("AlarmName").equal("tester")
+    alarm.should.have.key("Namespace").equal("tester_namespace")
+    alarm.should.have.key("MetricName").equal("tester_metric")
+    alarm.should.have.key("ComparisonOperator").equal("GreaterThanOrEqualToThreshold")
+    alarm.should.have.key("Threshold").equal(2.0)
+    alarm.should.have.key("Period").equal(60)
+    alarm.should.have.key("EvaluationPeriods").equal(5)
+    alarm.should.have.key("Statistic").should.equal("Average")
+    alarm.should.have.key("AlarmDescription").equal("A test")
+    alarm.should.have.key("Dimensions").equal(
+        [{"Name": "InstanceId", "Value": "i-0123457"}]
+    )
+    alarm.should.have.key("AlarmActions").equal(["arn:alarm"])
+    alarm.should.have.key("OKActions").equal(["arn:ok"])
+    alarm.should.have.key("InsufficientDataActions").equal(["arn:insufficient"])
+    alarm.should.have.key("Unit").equal("Seconds")
+    alarm.should.have.key("AlarmArn").equal(
+        "arn:aws:cloudwatch:{}:{}:alarm:{}".format(region, ACCOUNT_ID, name)
+    )
+
+
+@mock_cloudwatch
+def test_delete_alarm():
+    cloudwatch = boto3.client("cloudwatch", region_name="eu-central-1")
+
+    alarms = cloudwatch.describe_alarms()["MetricAlarms"]
+    alarms.should.have.length_of(0)
+
+    name = "tester"
+    cloudwatch.put_metric_alarm(
+        AlarmActions=["arn:alarm"],
+        AlarmDescription="A test",
+        AlarmName=name,
+        ComparisonOperator="GreaterThanOrEqualToThreshold",
+        Dimensions=[{"Name": "InstanceId", "Value": "i-0123457"}],
+        EvaluationPeriods=5,
+        InsufficientDataActions=["arn:insufficient"],
+        Namespace="{0}_namespace".format(name),
+        MetricName="{0}_metric".format(name),
+        OKActions=["arn:ok"],
+        Period=60,
+        Statistic="Average",
+        Threshold=2,
+        Unit="Seconds",
+    )
+
+    alarms = cloudwatch.describe_alarms()["MetricAlarms"]
+    alarms.should.have.length_of(1)
+
+    cloudwatch.delete_alarms(AlarmNames=[name])
+
+    alarms = cloudwatch.describe_alarms()["MetricAlarms"]
+    alarms.should.have.length_of(0)
+
+
+@mock_cloudwatch
+def test_delete_alarms_without_error():
+    # given
+    cloudwatch = boto3.client("cloudwatch", "eu-west-1")
+
+    # when/then
+    cloudwatch.delete_alarms(AlarmNames=["not-exists"])
+
+
+@mock_cloudwatch
+def test_describe_alarms_for_metric():
+    conn = boto3.client("cloudwatch", region_name="eu-central-1")
+    conn.put_metric_alarm(
+        AlarmName="testalarm1",
+        MetricName="cpu",
+        Namespace="blah",
+        Period=10,
+        EvaluationPeriods=5,
+        Statistic="Average",
+        Threshold=2,
+        ComparisonOperator="GreaterThanThreshold",
+        ActionsEnabled=True,
+    )
+    alarms = conn.describe_alarms_for_metric(MetricName="cpu", Namespace="blah")
+    alarms.get("MetricAlarms").should.have.length_of(1)
+
+    assert "testalarm1" in alarms.get("MetricAlarms")[0].get("AlarmArn")
+
+
+@mock_cloudwatch
+def test_describe_alarms():
+    conn = boto3.client("cloudwatch", region_name="eu-central-1")
+    conn.put_metric_alarm(
+        AlarmName="testalarm1",
+        MetricName="cpu",
+        Namespace="blah",
+        Period=10,
+        EvaluationPeriods=5,
+        Statistic="Average",
+        Threshold=2,
+        ComparisonOperator="GreaterThanThreshold",
+        ActionsEnabled=True,
+    )
+    metric_data_queries = [
+        {
+            "Id": "metricA",
+            "Expression": "metricB + metricC",
+            "Label": "metricA",
+            "ReturnData": True,
+        },
+        {
+            "Id": "metricB",
+            "MetricStat": {
+                "Metric": {
+                    "Namespace": "ns",
+                    "MetricName": "metricB",
+                    "Dimensions": [{"Name": "Name", "Value": "B"}],
+                },
+                "Period": 60,
+                "Stat": "Sum",
+            },
+            "ReturnData": False,
+        },
+        {
+            "Id": "metricC",
+            "MetricStat": {
+                "Metric": {
+                    "Namespace": "AWS/Lambda",
+                    "MetricName": "metricC",
+                    "Dimensions": [{"Name": "Name", "Value": "C"}],
+                },
+                "Period": 60,
+                "Stat": "Sum",
+                "Unit": "Seconds",
+            },
+            "ReturnData": False,
+        },
+    ]
+    conn.put_metric_alarm(
+        AlarmName="testalarm2",
+        EvaluationPeriods=1,
+        DatapointsToAlarm=1,
+        Metrics=metric_data_queries,
+        ComparisonOperator="GreaterThanThreshold",
+        Threshold=1.0,
+    )
+    alarms = conn.describe_alarms()
+    metric_alarms = alarms.get("MetricAlarms")
+    metric_alarms.should.have.length_of(2)
+    single_metric_alarm = [
+        alarm for alarm in metric_alarms if alarm["AlarmName"] == "testalarm1"
+    ][0]
+    multiple_metric_alarm = [
+        alarm for alarm in metric_alarms if alarm["AlarmName"] == "testalarm2"
+    ][0]
+
+    single_metric_alarm["MetricName"].should.equal("cpu")
+    single_metric_alarm.shouldnt.have.property("Metrics")
+    single_metric_alarm["Namespace"].should.equal("blah")
+    single_metric_alarm["Period"].should.equal(10)
+    single_metric_alarm["EvaluationPeriods"].should.equal(5)
+    single_metric_alarm["Statistic"].should.equal("Average")
+    single_metric_alarm["ComparisonOperator"].should.equal("GreaterThanThreshold")
+    single_metric_alarm["Threshold"].should.equal(2)
+
+    multiple_metric_alarm.shouldnt.have.property("MetricName")
+    multiple_metric_alarm["EvaluationPeriods"].should.equal(1)
+    multiple_metric_alarm["DatapointsToAlarm"].should.equal(1)
+    multiple_metric_alarm["Metrics"].should.equal(metric_data_queries)
+    multiple_metric_alarm["ComparisonOperator"].should.equal("GreaterThanThreshold")
+    multiple_metric_alarm["Threshold"].should.equal(1.0)
+
+
+@mock_cloudwatch
+def test_alarm_state():
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+
+    client.put_metric_alarm(
+        AlarmName="testalarm1",
+        MetricName="cpu",
+        Namespace="blah",
+        Period=10,
+        EvaluationPeriods=5,
+        Statistic="Average",
+        Threshold=2,
+        ComparisonOperator="GreaterThanThreshold",
+        ActionsEnabled=True,
+    )
+    client.put_metric_alarm(
+        AlarmName="testalarm2",
+        MetricName="cpu",
+        Namespace="blah",
+        Period=10,
+        EvaluationPeriods=5,
+        Statistic="Average",
+        Threshold=2,
+        ComparisonOperator="GreaterThanThreshold",
+    )
+
+    # This is tested implicitly as if it doesnt work the rest will die
+    client.set_alarm_state(
+        AlarmName="testalarm1",
+        StateValue="ALARM",
+        StateReason="testreason",
+        StateReasonData='{"some": "json_data"}',
+    )
+
+    resp = client.describe_alarms(StateValue="ALARM")
+    len(resp["MetricAlarms"]).should.equal(1)
+    resp["MetricAlarms"][0]["AlarmName"].should.equal("testalarm1")
+    resp["MetricAlarms"][0]["StateValue"].should.equal("ALARM")
+    resp["MetricAlarms"][0]["ActionsEnabled"].should.equal(True)
+
+    resp = client.describe_alarms(StateValue="OK")
+    len(resp["MetricAlarms"]).should.equal(1)
+    resp["MetricAlarms"][0]["AlarmName"].should.equal("testalarm2")
+    resp["MetricAlarms"][0]["StateValue"].should.equal("OK")
+    resp["MetricAlarms"][0]["ActionsEnabled"].should.equal(False)
+
+    # Just for sanity
+    resp = client.describe_alarms()
+    len(resp["MetricAlarms"]).should.equal(2)
diff --git a/tests/test_cloudwatch/test_cloudwatch_boto3.py b/tests/test_cloudwatch/test_cloudwatch_boto3.py
--- a/tests/test_cloudwatch/test_cloudwatch_boto3.py
+++ b/tests/test_cloudwatch/test_cloudwatch_boto3.py
@@ -1,345 +1,20 @@
-from datetime import datetime, timedelta
-from operator import itemgetter
-
 import boto3
+import pytest
+import pytz
+import sure  # noqa
+
 from botocore.exceptions import ClientError
+from datetime import datetime, timedelta
 from dateutil.tz import tzutc
+from decimal import Decimal
 from freezegun import freeze_time
-import pytest
+from operator import itemgetter
 from uuid import uuid4
-import pytz
-import sure  # noqa
 
 from moto import mock_cloudwatch
-from moto.cloudwatch.utils import make_arn_for_alarm
 from moto.core import ACCOUNT_ID
 
 
-@mock_cloudwatch
-def test_put_list_dashboard():
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
-
-    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
-    resp = client.list_dashboards()
-
-    len(resp["DashboardEntries"]).should.equal(1)
-
-
-@mock_cloudwatch
-def test_put_list_prefix_nomatch_dashboard():
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
-
-    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
-    resp = client.list_dashboards(DashboardNamePrefix="nomatch")
-
-    len(resp["DashboardEntries"]).should.equal(0)
-
-
-@mock_cloudwatch
-def test_delete_dashboard():
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
-
-    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
-    client.put_dashboard(DashboardName="test2", DashboardBody=widget)
-    client.put_dashboard(DashboardName="test3", DashboardBody=widget)
-    client.delete_dashboards(DashboardNames=["test2", "test1"])
-
-    resp = client.list_dashboards(DashboardNamePrefix="test3")
-    len(resp["DashboardEntries"]).should.equal(1)
-
-
-@mock_cloudwatch
-def test_delete_dashboard_fail():
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
-
-    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
-    client.put_dashboard(DashboardName="test2", DashboardBody=widget)
-    client.put_dashboard(DashboardName="test3", DashboardBody=widget)
-    # Doesnt delete anything if all dashboards to be deleted do not exist
-    try:
-        client.delete_dashboards(DashboardNames=["test2", "test1", "test_no_match"])
-    except ClientError as err:
-        err.response["Error"]["Code"].should.equal("ResourceNotFound")
-    else:
-        raise RuntimeError("Should of raised error")
-
-    resp = client.list_dashboards()
-    len(resp["DashboardEntries"]).should.equal(3)
-
-
-@mock_cloudwatch
-def test_get_dashboard():
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
-    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
-
-    resp = client.get_dashboard(DashboardName="test1")
-    resp.should.contain("DashboardArn")
-    resp.should.contain("DashboardBody")
-    resp["DashboardName"].should.equal("test1")
-
-
-@mock_cloudwatch
-def test_get_dashboard_fail():
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-
-    try:
-        client.get_dashboard(DashboardName="test1")
-    except ClientError as err:
-        err.response["Error"]["Code"].should.equal("ResourceNotFound")
-    else:
-        raise RuntimeError("Should have raised error")
-
-
-@mock_cloudwatch
-def test_create_alarm():
-    region = "eu-west-1"
-    cloudwatch = boto3.client("cloudwatch", region)
-
-    name = "tester"
-    cloudwatch.put_metric_alarm(
-        AlarmActions=["arn:alarm"],
-        AlarmDescription="A test",
-        AlarmName=name,
-        ComparisonOperator="GreaterThanOrEqualToThreshold",
-        Dimensions=[{"Name": "InstanceId", "Value": "i-0123457"}],
-        EvaluationPeriods=5,
-        InsufficientDataActions=["arn:insufficient"],
-        Namespace="{0}_namespace".format(name),
-        MetricName="{0}_metric".format(name),
-        OKActions=["arn:ok"],
-        Period=60,
-        Statistic="Average",
-        Threshold=2,
-        Unit="Seconds",
-    )
-
-    alarms = cloudwatch.describe_alarms()["MetricAlarms"]
-    alarms.should.have.length_of(1)
-    alarm = alarms[0]
-    alarm.should.have.key("AlarmName").equal("tester")
-    alarm.should.have.key("Namespace").equal("tester_namespace")
-    alarm.should.have.key("MetricName").equal("tester_metric")
-    alarm.should.have.key("ComparisonOperator").equal("GreaterThanOrEqualToThreshold")
-    alarm.should.have.key("Threshold").equal(2.0)
-    alarm.should.have.key("Period").equal(60)
-    alarm.should.have.key("EvaluationPeriods").equal(5)
-    alarm.should.have.key("Statistic").should.equal("Average")
-    alarm.should.have.key("AlarmDescription").equal("A test")
-    alarm.should.have.key("Dimensions").equal(
-        [{"Name": "InstanceId", "Value": "i-0123457"}]
-    )
-    alarm.should.have.key("AlarmActions").equal(["arn:alarm"])
-    alarm.should.have.key("OKActions").equal(["arn:ok"])
-    alarm.should.have.key("InsufficientDataActions").equal(["arn:insufficient"])
-    alarm.should.have.key("Unit").equal("Seconds")
-    alarm.should.have.key("AlarmArn").equal(
-        "arn:aws:cloudwatch:{}:{}:alarm:{}".format(region, ACCOUNT_ID, name)
-    )
-
-
-@mock_cloudwatch
-def test_delete_alarm():
-    cloudwatch = boto3.client("cloudwatch", region_name="eu-central-1")
-
-    alarms = cloudwatch.describe_alarms()["MetricAlarms"]
-    alarms.should.have.length_of(0)
-
-    name = "tester"
-    cloudwatch.put_metric_alarm(
-        AlarmActions=["arn:alarm"],
-        AlarmDescription="A test",
-        AlarmName=name,
-        ComparisonOperator="GreaterThanOrEqualToThreshold",
-        Dimensions=[{"Name": "InstanceId", "Value": "i-0123457"}],
-        EvaluationPeriods=5,
-        InsufficientDataActions=["arn:insufficient"],
-        Namespace="{0}_namespace".format(name),
-        MetricName="{0}_metric".format(name),
-        OKActions=["arn:ok"],
-        Period=60,
-        Statistic="Average",
-        Threshold=2,
-        Unit="Seconds",
-    )
-
-    alarms = cloudwatch.describe_alarms()["MetricAlarms"]
-    alarms.should.have.length_of(1)
-
-    cloudwatch.delete_alarms(AlarmNames=[name])
-
-    alarms = cloudwatch.describe_alarms()["MetricAlarms"]
-    alarms.should.have.length_of(0)
-
-
-@mock_cloudwatch
-def test_delete_alarms_without_error():
-    # given
-    cloudwatch = boto3.client("cloudwatch", "eu-west-1")
-
-    # when/then
-    cloudwatch.delete_alarms(AlarmNames=["not-exists"])
-
-
-@mock_cloudwatch
-def test_describe_alarms_for_metric():
-    conn = boto3.client("cloudwatch", region_name="eu-central-1")
-    conn.put_metric_alarm(
-        AlarmName="testalarm1",
-        MetricName="cpu",
-        Namespace="blah",
-        Period=10,
-        EvaluationPeriods=5,
-        Statistic="Average",
-        Threshold=2,
-        ComparisonOperator="GreaterThanThreshold",
-        ActionsEnabled=True,
-    )
-    alarms = conn.describe_alarms_for_metric(MetricName="cpu", Namespace="blah")
-    alarms.get("MetricAlarms").should.have.length_of(1)
-
-    assert "testalarm1" in alarms.get("MetricAlarms")[0].get("AlarmArn")
-
-
-@mock_cloudwatch
-def test_describe_alarms():
-    conn = boto3.client("cloudwatch", region_name="eu-central-1")
-    conn.put_metric_alarm(
-        AlarmName="testalarm1",
-        MetricName="cpu",
-        Namespace="blah",
-        Period=10,
-        EvaluationPeriods=5,
-        Statistic="Average",
-        Threshold=2,
-        ComparisonOperator="GreaterThanThreshold",
-        ActionsEnabled=True,
-    )
-    metric_data_queries = [
-        {
-            "Id": "metricA",
-            "Expression": "metricB + metricC",
-            "Label": "metricA",
-            "ReturnData": True,
-        },
-        {
-            "Id": "metricB",
-            "MetricStat": {
-                "Metric": {
-                    "Namespace": "ns",
-                    "MetricName": "metricB",
-                    "Dimensions": [{"Name": "Name", "Value": "B"}],
-                },
-                "Period": 60,
-                "Stat": "Sum",
-            },
-            "ReturnData": False,
-        },
-        {
-            "Id": "metricC",
-            "MetricStat": {
-                "Metric": {
-                    "Namespace": "AWS/Lambda",
-                    "MetricName": "metricC",
-                    "Dimensions": [{"Name": "Name", "Value": "C"}],
-                },
-                "Period": 60,
-                "Stat": "Sum",
-                "Unit": "Seconds",
-            },
-            "ReturnData": False,
-        },
-    ]
-    conn.put_metric_alarm(
-        AlarmName="testalarm2",
-        EvaluationPeriods=1,
-        DatapointsToAlarm=1,
-        Metrics=metric_data_queries,
-        ComparisonOperator="GreaterThanThreshold",
-        Threshold=1.0,
-    )
-    alarms = conn.describe_alarms()
-    metric_alarms = alarms.get("MetricAlarms")
-    metric_alarms.should.have.length_of(2)
-    single_metric_alarm = [
-        alarm for alarm in metric_alarms if alarm["AlarmName"] == "testalarm1"
-    ][0]
-    multiple_metric_alarm = [
-        alarm for alarm in metric_alarms if alarm["AlarmName"] == "testalarm2"
-    ][0]
-
-    single_metric_alarm["MetricName"].should.equal("cpu")
-    single_metric_alarm.shouldnt.have.property("Metrics")
-    single_metric_alarm["Namespace"].should.equal("blah")
-    single_metric_alarm["Period"].should.equal(10)
-    single_metric_alarm["EvaluationPeriods"].should.equal(5)
-    single_metric_alarm["Statistic"].should.equal("Average")
-    single_metric_alarm["ComparisonOperator"].should.equal("GreaterThanThreshold")
-    single_metric_alarm["Threshold"].should.equal(2)
-
-    multiple_metric_alarm.shouldnt.have.property("MetricName")
-    multiple_metric_alarm["EvaluationPeriods"].should.equal(1)
-    multiple_metric_alarm["DatapointsToAlarm"].should.equal(1)
-    multiple_metric_alarm["Metrics"].should.equal(metric_data_queries)
-    multiple_metric_alarm["ComparisonOperator"].should.equal("GreaterThanThreshold")
-    multiple_metric_alarm["Threshold"].should.equal(1.0)
-
-
-@mock_cloudwatch
-def test_alarm_state():
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-
-    client.put_metric_alarm(
-        AlarmName="testalarm1",
-        MetricName="cpu",
-        Namespace="blah",
-        Period=10,
-        EvaluationPeriods=5,
-        Statistic="Average",
-        Threshold=2,
-        ComparisonOperator="GreaterThanThreshold",
-        ActionsEnabled=True,
-    )
-    client.put_metric_alarm(
-        AlarmName="testalarm2",
-        MetricName="cpu",
-        Namespace="blah",
-        Period=10,
-        EvaluationPeriods=5,
-        Statistic="Average",
-        Threshold=2,
-        ComparisonOperator="GreaterThanThreshold",
-    )
-
-    # This is tested implicitly as if it doesnt work the rest will die
-    client.set_alarm_state(
-        AlarmName="testalarm1",
-        StateValue="ALARM",
-        StateReason="testreason",
-        StateReasonData='{"some": "json_data"}',
-    )
-
-    resp = client.describe_alarms(StateValue="ALARM")
-    len(resp["MetricAlarms"]).should.equal(1)
-    resp["MetricAlarms"][0]["AlarmName"].should.equal("testalarm1")
-    resp["MetricAlarms"][0]["StateValue"].should.equal("ALARM")
-    resp["MetricAlarms"][0]["ActionsEnabled"].should.equal(True)
-
-    resp = client.describe_alarms(StateValue="OK")
-    len(resp["MetricAlarms"]).should.equal(1)
-    resp["MetricAlarms"][0]["AlarmName"].should.equal("testalarm2")
-    resp["MetricAlarms"][0]["StateValue"].should.equal("OK")
-    resp["MetricAlarms"][0]["ActionsEnabled"].should.equal(False)
-
-    # Just for sanity
-    resp = client.describe_alarms()
-    len(resp["MetricAlarms"]).should.equal(2)
-
-
 @mock_cloudwatch
 def test_put_metric_data_no_dimensions():
     conn = boto3.client("cloudwatch", region_name="us-east-1")
@@ -355,6 +30,29 @@ def test_put_metric_data_no_dimensions():
     metric["MetricName"].should.equal("metric")
 
 
+@mock_cloudwatch
+def test_put_metric_data_can_not_have_nan():
+    client = boto3.client("cloudwatch", region_name="us-west-2")
+    utc_now = datetime.now(tz=pytz.utc)
+    with pytest.raises(ClientError) as exc:
+        client.put_metric_data(
+            Namespace="mynamespace",
+            MetricData=[
+                {
+                    "MetricName": "mymetric",
+                    "Timestamp": utc_now,
+                    "Value": Decimal("NaN"),
+                    "Unit": "Count",
+                }
+            ],
+        )
+    err = exc.value.response["Error"]
+    err["Code"].should.equal("InvalidParameterValue")
+    err["Message"].should.equal(
+        "The value NaN for parameter MetricData.member.1.Value is invalid."
+    )
+
+
 @mock_cloudwatch
 def test_put_metric_data_with_statistics():
     conn = boto3.client("cloudwatch", region_name="us-east-1")
@@ -1257,178 +955,3 @@ def test_put_metric_alarm_error_evaluate_low_sample_count_percentile():
         "Option unknown is not supported. "
         "Supported options for parameter EvaluateLowSampleCountPercentile are evaluate and ignore."
     )
-
-
-@mock_cloudwatch
-def test_list_tags_for_resource():
-    # given
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-    alarm_name = "test-alarm"
-    client.put_metric_alarm(
-        AlarmName=alarm_name,
-        AlarmDescription="test alarm",
-        ActionsEnabled=True,
-        MetricName="5XXError",
-        Namespace="AWS/ApiGateway",
-        Statistic="Sum",
-        Dimensions=[
-            {"Name": "ApiName", "Value": "test-api"},
-            {"Name": "Stage", "Value": "default"},
-        ],
-        Period=60,
-        Unit="Seconds",
-        EvaluationPeriods=1,
-        DatapointsToAlarm=1,
-        Threshold=1.0,
-        ComparisonOperator="GreaterThanOrEqualToThreshold",
-        Tags=[{"Key": "key-1", "Value": "value-1"}],
-    )
-    arn = client.describe_alarms(AlarmNames=[alarm_name])["MetricAlarms"][0]["AlarmArn"]
-
-    # when
-    response = client.list_tags_for_resource(ResourceARN=arn)
-
-    # then
-    response["Tags"].should.equal([{"Key": "key-1", "Value": "value-1"}])
-
-
-@mock_cloudwatch
-def test_list_tags_for_resource_with_unknown_resource():
-    # given
-    region_name = "eu-central-1"
-    client = boto3.client("cloudwatch", region_name=region_name)
-
-    # when
-    response = client.list_tags_for_resource(
-        ResourceARN=make_arn_for_alarm(
-            region=region_name, account_id=ACCOUNT_ID, alarm_name="unknown"
-        )
-    )
-
-    # then
-    response["Tags"].should.be.empty
-
-
-@mock_cloudwatch
-def test_tag_resource():
-    # given
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-    alarm_name = "test-alarm"
-    client.put_metric_alarm(
-        AlarmName=alarm_name,
-        AlarmDescription="test alarm",
-        ActionsEnabled=True,
-        MetricName="5XXError",
-        Namespace="AWS/ApiGateway",
-        Statistic="Sum",
-        Dimensions=[
-            {"Name": "ApiName", "Value": "test-api"},
-            {"Name": "Stage", "Value": "default"},
-        ],
-        Period=60,
-        Unit="Seconds",
-        EvaluationPeriods=1,
-        DatapointsToAlarm=1,
-        Threshold=1.0,
-        ComparisonOperator="GreaterThanOrEqualToThreshold",
-        Tags=[{"Key": "key-1", "Value": "value-1"}],
-    )
-    arn = client.describe_alarms(AlarmNames=[alarm_name])["MetricAlarms"][0]["AlarmArn"]
-
-    # when
-    client.tag_resource(ResourceARN=arn, Tags=[{"Key": "key-2", "Value": "value-2"}])
-
-    # then
-    response = client.list_tags_for_resource(ResourceARN=arn)
-    sorted(response["Tags"], key=itemgetter("Key")).should.equal(
-        sorted(
-            [
-                {"Key": "key-1", "Value": "value-1"},
-                {"Key": "key-2", "Value": "value-2"},
-            ],
-            key=itemgetter("Key"),
-        )
-    )
-
-
-@mock_cloudwatch
-def test_tag_resource_error_not_exists():
-    # given
-    region_name = "eu-central-1"
-    client = boto3.client("cloudwatch", region_name=region_name)
-
-    # when
-    with pytest.raises(ClientError) as e:
-        client.tag_resource(
-            ResourceARN=make_arn_for_alarm(
-                region=region_name, account_id=ACCOUNT_ID, alarm_name="unknown"
-            ),
-            Tags=[{"Key": "key-1", "Value": "value-1"},],
-        )
-
-    # then
-    ex = e.value
-    ex.operation_name.should.equal("TagResource")
-    ex.response["ResponseMetadata"]["HTTPStatusCode"].should.equal(404)
-    ex.response["Error"]["Code"].should.contain("ResourceNotFoundException")
-    ex.response["Error"]["Message"].should.equal("Unknown")
-
-
-@mock_cloudwatch
-def test_untag_resource():
-    # given
-    client = boto3.client("cloudwatch", region_name="eu-central-1")
-    alarm_name = "test-alarm"
-    client.put_metric_alarm(
-        AlarmName=alarm_name,
-        AlarmDescription="test alarm",
-        ActionsEnabled=True,
-        MetricName="5XXError",
-        Namespace="AWS/ApiGateway",
-        Statistic="Sum",
-        Dimensions=[
-            {"Name": "ApiName", "Value": "test-api"},
-            {"Name": "Stage", "Value": "default"},
-        ],
-        Period=60,
-        Unit="Seconds",
-        EvaluationPeriods=1,
-        DatapointsToAlarm=1,
-        Threshold=1.0,
-        ComparisonOperator="GreaterThanOrEqualToThreshold",
-        Tags=[
-            {"Key": "key-1", "Value": "value-1"},
-            {"Key": "key-2", "Value": "value-2"},
-        ],
-    )
-    arn = client.describe_alarms(AlarmNames=[alarm_name])["MetricAlarms"][0]["AlarmArn"]
-
-    # when
-    client.untag_resource(ResourceARN=arn, TagKeys=["key-2"])
-
-    # then
-    response = client.list_tags_for_resource(ResourceARN=arn)
-    response["Tags"].should.equal([{"Key": "key-1", "Value": "value-1"}])
-
-
-@mock_cloudwatch
-def test_untag_resource_error_not_exists():
-    # given
-    region_name = "eu-central-1"
-    client = boto3.client("cloudwatch", region_name=region_name)
-
-    # when
-    with pytest.raises(ClientError) as e:
-        client.untag_resource(
-            ResourceARN=make_arn_for_alarm(
-                region=region_name, account_id=ACCOUNT_ID, alarm_name="unknown"
-            ),
-            TagKeys=["key-1"],
-        )
-
-    # then
-    ex = e.value
-    ex.operation_name.should.equal("UntagResource")
-    ex.response["ResponseMetadata"]["HTTPStatusCode"].should.equal(404)
-    ex.response["Error"]["Code"].should.contain("ResourceNotFoundException")
-    ex.response["Error"]["Message"].should.equal("Unknown")
diff --git a/tests/test_cloudwatch/test_cloudwatch_dashboards.py b/tests/test_cloudwatch/test_cloudwatch_dashboards.py
new file mode 100644
--- /dev/null
+++ b/tests/test_cloudwatch/test_cloudwatch_dashboards.py
@@ -0,0 +1,85 @@
+import boto3
+from botocore.exceptions import ClientError
+import sure  # noqa
+
+from moto import mock_cloudwatch
+
+
+@mock_cloudwatch
+def test_put_list_dashboard():
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
+
+    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
+    resp = client.list_dashboards()
+
+    len(resp["DashboardEntries"]).should.equal(1)
+
+
+@mock_cloudwatch
+def test_put_list_prefix_nomatch_dashboard():
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
+
+    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
+    resp = client.list_dashboards(DashboardNamePrefix="nomatch")
+
+    len(resp["DashboardEntries"]).should.equal(0)
+
+
+@mock_cloudwatch
+def test_delete_dashboard():
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
+
+    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
+    client.put_dashboard(DashboardName="test2", DashboardBody=widget)
+    client.put_dashboard(DashboardName="test3", DashboardBody=widget)
+    client.delete_dashboards(DashboardNames=["test2", "test1"])
+
+    resp = client.list_dashboards(DashboardNamePrefix="test3")
+    len(resp["DashboardEntries"]).should.equal(1)
+
+
+@mock_cloudwatch
+def test_delete_dashboard_fail():
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
+
+    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
+    client.put_dashboard(DashboardName="test2", DashboardBody=widget)
+    client.put_dashboard(DashboardName="test3", DashboardBody=widget)
+    # Doesnt delete anything if all dashboards to be deleted do not exist
+    try:
+        client.delete_dashboards(DashboardNames=["test2", "test1", "test_no_match"])
+    except ClientError as err:
+        err.response["Error"]["Code"].should.equal("ResourceNotFound")
+    else:
+        raise RuntimeError("Should of raised error")
+
+    resp = client.list_dashboards()
+    len(resp["DashboardEntries"]).should.equal(3)
+
+
+@mock_cloudwatch
+def test_get_dashboard():
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+    widget = '{"widgets": [{"type": "text", "x": 0, "y": 7, "width": 3, "height": 3, "properties": {"markdown": "Hello world"}}]}'
+    client.put_dashboard(DashboardName="test1", DashboardBody=widget)
+
+    resp = client.get_dashboard(DashboardName="test1")
+    resp.should.contain("DashboardArn")
+    resp.should.contain("DashboardBody")
+    resp["DashboardName"].should.equal("test1")
+
+
+@mock_cloudwatch
+def test_get_dashboard_fail():
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+
+    try:
+        client.get_dashboard(DashboardName="test1")
+    except ClientError as err:
+        err.response["Error"]["Code"].should.equal("ResourceNotFound")
+    else:
+        raise RuntimeError("Should have raised error")
diff --git a/tests/test_cloudwatch/test_cloudwatch_tags.py b/tests/test_cloudwatch/test_cloudwatch_tags.py
new file mode 100644
--- /dev/null
+++ b/tests/test_cloudwatch/test_cloudwatch_tags.py
@@ -0,0 +1,185 @@
+from operator import itemgetter
+
+import boto3
+from botocore.exceptions import ClientError
+import pytest
+import sure  # noqa
+
+from moto import mock_cloudwatch
+from moto.cloudwatch.utils import make_arn_for_alarm
+from moto.core import ACCOUNT_ID
+
+
+@mock_cloudwatch
+def test_list_tags_for_resource():
+    # given
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+    alarm_name = "test-alarm"
+    client.put_metric_alarm(
+        AlarmName=alarm_name,
+        AlarmDescription="test alarm",
+        ActionsEnabled=True,
+        MetricName="5XXError",
+        Namespace="AWS/ApiGateway",
+        Statistic="Sum",
+        Dimensions=[
+            {"Name": "ApiName", "Value": "test-api"},
+            {"Name": "Stage", "Value": "default"},
+        ],
+        Period=60,
+        Unit="Seconds",
+        EvaluationPeriods=1,
+        DatapointsToAlarm=1,
+        Threshold=1.0,
+        ComparisonOperator="GreaterThanOrEqualToThreshold",
+        Tags=[{"Key": "key-1", "Value": "value-1"}],
+    )
+    arn = client.describe_alarms(AlarmNames=[alarm_name])["MetricAlarms"][0]["AlarmArn"]
+
+    # when
+    response = client.list_tags_for_resource(ResourceARN=arn)
+
+    # then
+    response["Tags"].should.equal([{"Key": "key-1", "Value": "value-1"}])
+
+
+@mock_cloudwatch
+def test_list_tags_for_resource_with_unknown_resource():
+    # given
+    region_name = "eu-central-1"
+    client = boto3.client("cloudwatch", region_name=region_name)
+
+    # when
+    response = client.list_tags_for_resource(
+        ResourceARN=make_arn_for_alarm(
+            region=region_name, account_id=ACCOUNT_ID, alarm_name="unknown"
+        )
+    )
+
+    # then
+    response["Tags"].should.be.empty
+
+
+@mock_cloudwatch
+def test_tag_resource():
+    # given
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+    alarm_name = "test-alarm"
+    client.put_metric_alarm(
+        AlarmName=alarm_name,
+        AlarmDescription="test alarm",
+        ActionsEnabled=True,
+        MetricName="5XXError",
+        Namespace="AWS/ApiGateway",
+        Statistic="Sum",
+        Dimensions=[
+            {"Name": "ApiName", "Value": "test-api"},
+            {"Name": "Stage", "Value": "default"},
+        ],
+        Period=60,
+        Unit="Seconds",
+        EvaluationPeriods=1,
+        DatapointsToAlarm=1,
+        Threshold=1.0,
+        ComparisonOperator="GreaterThanOrEqualToThreshold",
+        Tags=[{"Key": "key-1", "Value": "value-1"}],
+    )
+    arn = client.describe_alarms(AlarmNames=[alarm_name])["MetricAlarms"][0]["AlarmArn"]
+
+    # when
+    client.tag_resource(ResourceARN=arn, Tags=[{"Key": "key-2", "Value": "value-2"}])
+
+    # then
+    response = client.list_tags_for_resource(ResourceARN=arn)
+    sorted(response["Tags"], key=itemgetter("Key")).should.equal(
+        sorted(
+            [
+                {"Key": "key-1", "Value": "value-1"},
+                {"Key": "key-2", "Value": "value-2"},
+            ],
+            key=itemgetter("Key"),
+        )
+    )
+
+
+@mock_cloudwatch
+def test_tag_resource_error_not_exists():
+    # given
+    region_name = "eu-central-1"
+    client = boto3.client("cloudwatch", region_name=region_name)
+
+    # when
+    with pytest.raises(ClientError) as e:
+        client.tag_resource(
+            ResourceARN=make_arn_for_alarm(
+                region=region_name, account_id=ACCOUNT_ID, alarm_name="unknown"
+            ),
+            Tags=[{"Key": "key-1", "Value": "value-1"},],
+        )
+
+    # then
+    ex = e.value
+    ex.operation_name.should.equal("TagResource")
+    ex.response["ResponseMetadata"]["HTTPStatusCode"].should.equal(404)
+    ex.response["Error"]["Code"].should.contain("ResourceNotFoundException")
+    ex.response["Error"]["Message"].should.equal("Unknown")
+
+
+@mock_cloudwatch
+def test_untag_resource():
+    # given
+    client = boto3.client("cloudwatch", region_name="eu-central-1")
+    alarm_name = "test-alarm"
+    client.put_metric_alarm(
+        AlarmName=alarm_name,
+        AlarmDescription="test alarm",
+        ActionsEnabled=True,
+        MetricName="5XXError",
+        Namespace="AWS/ApiGateway",
+        Statistic="Sum",
+        Dimensions=[
+            {"Name": "ApiName", "Value": "test-api"},
+            {"Name": "Stage", "Value": "default"},
+        ],
+        Period=60,
+        Unit="Seconds",
+        EvaluationPeriods=1,
+        DatapointsToAlarm=1,
+        Threshold=1.0,
+        ComparisonOperator="GreaterThanOrEqualToThreshold",
+        Tags=[
+            {"Key": "key-1", "Value": "value-1"},
+            {"Key": "key-2", "Value": "value-2"},
+        ],
+    )
+    arn = client.describe_alarms(AlarmNames=[alarm_name])["MetricAlarms"][0]["AlarmArn"]
+
+    # when
+    client.untag_resource(ResourceARN=arn, TagKeys=["key-2"])
+
+    # then
+    response = client.list_tags_for_resource(ResourceARN=arn)
+    response["Tags"].should.equal([{"Key": "key-1", "Value": "value-1"}])
+
+
+@mock_cloudwatch
+def test_untag_resource_error_not_exists():
+    # given
+    region_name = "eu-central-1"
+    client = boto3.client("cloudwatch", region_name=region_name)
+
+    # when
+    with pytest.raises(ClientError) as e:
+        client.untag_resource(
+            ResourceARN=make_arn_for_alarm(
+                region=region_name, account_id=ACCOUNT_ID, alarm_name="unknown"
+            ),
+            TagKeys=["key-1"],
+        )
+
+    # then
+    ex = e.value
+    ex.operation_name.should.equal("UntagResource")
+    ex.response["ResponseMetadata"]["HTTPStatusCode"].should.equal(404)
+    ex.response["Error"]["Code"].should.contain("ResourceNotFoundException")
+    ex.response["Error"]["Message"].should.equal("Unknown")