From 54b6608bf8d4356ddf50f6e2cc15a20a8b83bd38 Mon Sep 17 00:00:00 2001
From: Nikhil <nikhil@policyengine.org>
Date: Fri, 10 Dec 2021 10:51:07 +0000
Subject: [PATCH 1/2] Add string to allowed types

---
 openfisca_core/parameters/config.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/openfisca_core/parameters/config.py b/openfisca_core/parameters/config.py
index e9a3041ae8..b380efa856 100644
--- a/openfisca_core/parameters/config.py
+++ b/openfisca_core/parameters/config.py
@@ -19,7 +19,7 @@
 
 # 'unit' and 'reference' are only listed here for backward compatibility.
 #  It is now recommended to include them in metadata, until a common consensus emerges.
-ALLOWED_PARAM_TYPES = (float, int, bool, type(None), typing.List)
+ALLOWED_PARAM_TYPES = (float, int, bool, type(None), typing.List, str)
 COMMON_KEYS = {'description', 'metadata', 'unit', 'reference', 'documentation'}
 FILE_EXTENSIONS = {'.yaml', '.yml'}
 

From 18cd0c106524a09b5ff0af5a78be7de19855ee4f Mon Sep 17 00:00:00 2001
From: Nikhil <nikhil@policyengine.org>
Date: Fri, 10 Dec 2021 10:51:29 +0000
Subject: [PATCH 2/2] Add new test and remove now incorrect test

---
 tests/core/parameter_validation/string_parameter.yaml    | 9 +++++++++
 .../parameter_validation/test_parameter_validation.py    | 8 +++++++-
 tests/core/parameter_validation/wrong_value.yaml         | 3 ---
 3 files changed, 16 insertions(+), 4 deletions(-)
 create mode 100644 tests/core/parameter_validation/string_parameter.yaml
 delete mode 100644 tests/core/parameter_validation/wrong_value.yaml

diff --git a/tests/core/parameter_validation/string_parameter.yaml b/tests/core/parameter_validation/string_parameter.yaml
new file mode 100644
index 0000000000..e88f5286ed
--- /dev/null
+++ b/tests/core/parameter_validation/string_parameter.yaml
@@ -0,0 +1,9 @@
+description: A parameter with a string value
+values:
+  2015-01-01: string, without metadata
+  2016-01-01:
+    value: string, with metadata
+    metadata:
+      unit: string
+      period: year
+      reference: none provided
diff --git a/tests/core/parameter_validation/test_parameter_validation.py b/tests/core/parameter_validation/test_parameter_validation.py
index 62b2b0c132..ddb7119324 100644
--- a/tests/core/parameter_validation/test_parameter_validation.py
+++ b/tests/core/parameter_validation/test_parameter_validation.py
@@ -23,7 +23,6 @@ def check_fails_with_message(file_name, keywords):
     ('indentation', {'Invalid YAML', 'indentation.yaml', 'line 2', 'mapping values are not allowed'}),
     ("wrong_date", {"Error parsing parameter file", "Properties must be valid YYYY-MM-DD instants"}),
     ('wrong_scale', {'Unexpected property', 'scale[1]', 'treshold'}),
-    ('wrong_value', {'not one of the allowed types', 'wrong_value[2015-12-01]', '1A'}),
     ('unexpected_key_in_parameter', {'Unexpected property', 'unexpected_key'}),
     ('wrong_type_in_parameter', {'must be of type object'}),
     ('wrong_type_in_value_history', {'must be of type object'}),
@@ -58,3 +57,10 @@ def test_yaml_hierarchy():
     parameters = ParameterNode('', directory_path = path)
     parameters_at_instant = parameters('2016-01-01')
     assert parameters_at_instant.node1.param == 1.0
+
+
+def test_string_parameter():
+    path = os.path.join(BASE_DIR, 'string_parameter.yaml')
+    parameter = load_parameter_file(path, 'string_parameter')
+    assert parameter("2015-01-01") == "string, without metadata"
+    assert parameter("2016-01-01") == "string, with metadata"
diff --git a/tests/core/parameter_validation/wrong_value.yaml b/tests/core/parameter_validation/wrong_value.yaml
deleted file mode 100644
index f120c81ac7..0000000000
--- a/tests/core/parameter_validation/wrong_value.yaml
+++ /dev/null
@@ -1,3 +0,0 @@
-values:
-  2015-12-01:
-    value: 1A