[Feat] Add support for f-string syntax in PromptTemplate (#38)

* Add support for f-string syntax in PromptTemplate

tests/test_template.py

@@ -4,7 +4,7 @@ from kotaemon.prompt.template import PromptTemplate
 
 
 def test_prompt_template_creation():
-    # Test case 1: Ensure the PromptTemplate object is created correctly
+    # Ensure the PromptTemplate object is created correctly
     template_string = "This is a template"
     template = PromptTemplate(template_string)
     assert template.template == template_string
@@ -15,8 +15,22 @@ def test_prompt_template_creation():
     assert template.placeholders == {"name", "day"}
 
 
+def test_prompt_template_creation_invalid_placeholder():
+    # Ensure the PromptTemplate object handle invalid placeholder correctly
+    template_string = "Hello, {name}! Today is {0day}."
+
+    with pytest.raises(ValueError):
+        PromptTemplate(template_string, ignore_invalid=False)
+
+    with pytest.warns(
+        UserWarning,
+        match="Ignore invalid placeholder: 0day.",
+    ):
+        PromptTemplate(template_string, ignore_invalid=True)
+
+
 def test_prompt_template_addition():
-    # Test case 2: Ensure the __add__ method concatenates the templates correctly
+    # Ensure the __add__ method concatenates the templates correctly
     template1 = PromptTemplate("Hello, ")
     template2 = PromptTemplate("world!")
     result = template1 + template2
@@ -29,25 +43,71 @@ def test_prompt_template_addition():
 
 
 def test_prompt_template_extract_placeholders():
-    # Test case 3: Ensure the extract_placeholders method extracts placeholders
-    # correctly
+    # Ensure the PromptTemplate correctly extracts placeholders
     template_string = "Hello, {name}! Today is {day}."
-    result = PromptTemplate.extract_placeholders(template_string)
+    result = PromptTemplate(template_string).placeholders
     assert result == {"name", "day"}
 
 
 def test_prompt_template_populate():
-    # Test case 4: Ensure the populate method populates the template correctly
+    # Ensure the populate method populates the template correctly
     template_string = "Hello, {name}! Today is {day}."
     template = PromptTemplate(template_string)
     result = template.populate(name="John", day="Monday")
     assert result == "Hello, John! Today is Monday."
 
 
-def test_prompt_template_unknown_placeholder():
-    # Test case 5: Ensure the populate method raises an exception for unknown
-    # placeholders
+def test_prompt_template_check_missing_kwargs():
+    # Ensure the check_missing_kwargs and populate methods raise an exception for
+    # missing placeholders
     template_string = "Hello, {name}! Today is {day}."
     template = PromptTemplate(template_string)
+    kwargs = dict(name="John")
+
     with pytest.raises(ValueError):
-        template.populate(name="John", month="January")
+        template.check_missing_kwargs(**kwargs)
+
+    with pytest.raises(ValueError):
+        template.populate(**kwargs)
+
+
+def test_prompt_template_check_redundant_kwargs():
+    # Ensure the check_redundant_kwargs, partial_populate and populate methods warn for
+    # redundant placeholders
+    template_string = "Hello, {name}! Today is {day}."
+    template = PromptTemplate(template_string)
+    kwargs = dict(name="John", day="Monday", age="30")
+
+    with pytest.warns(UserWarning, match="Keys provided but not in template: age"):
+        template.check_redundant_kwargs(**kwargs)
+
+    with pytest.warns(UserWarning, match="Keys provided but not in template: age"):
+        template.partial_populate(**kwargs)
+
+    with pytest.warns(UserWarning, match="Keys provided but not in template: age"):
+        template.populate(**kwargs)
+
+
+def test_prompt_template_populate_complex_template():
+    # Ensure the populate method produces the same results as the built-in str.format
+    # function
+    template_string = (
+        "a = {a:.2f}, b = {b}, c = {c:.1%}, d = {d:#.0g}, ascii of {e} = {e!a:>2}"
+    )
+    template = PromptTemplate(template_string)
+    kwargs = dict(a=1, b="two", c=3, d=4, e="á")
+    populated = template.populate(**kwargs)
+    expected = template_string.format(**kwargs)
+    assert populated == expected
+
+
+def test_prompt_template_partial_populate():
+    # Ensure the partial_populate method populates correctly
+    template_string = (
+        "a = {a:.2f}, b = {b}, c = {c:.1%}, d = {d:#.0g}, ascii of {e} = {e!a:>2}"
+    )
+    template = PromptTemplate(template_string)
+    kwargs = dict(a=1, b="two", d=4, e="á")
+    populated = template.partial_populate(**kwargs)
+    expected = "a = 1.00, b = two, c = {c:.1%}, d = 4., ascii of á = '\\xe1'"
+    assert populated == expected