add few shot example (#148)

tests/unit_tests/prompts/test_prompt.py

@@ -0,0 +1,89 @@
+"""Test functionality related to prompts."""
+import pytest
+
+from langchain.prompts.prompt import PromptTemplate
+
+
+def test_prompt_valid() -> None:
+    """Test prompts can be constructed."""
+    template = "This is a {foo} test."
+    input_variables = ["foo"]
+    prompt = PromptTemplate(input_variables=input_variables, template=template)
+    assert prompt.template == template
+    assert prompt.input_variables == input_variables
+
+
+def test_prompt_missing_input_variables() -> None:
+    """Test error is raised when input variables are not provided."""
+    template = "This is a {foo} test."
+    input_variables: list = []
+    with pytest.raises(ValueError):
+        PromptTemplate(input_variables=input_variables, template=template)
+
+
+def test_prompt_extra_input_variables() -> None:
+    """Test error is raised when there are too many input variables."""
+    template = "This is a {foo} test."
+    input_variables = ["foo", "bar"]
+    with pytest.raises(ValueError):
+        PromptTemplate(input_variables=input_variables, template=template)
+
+
+def test_prompt_wrong_input_variables() -> None:
+    """Test error is raised when name of input variable is wrong."""
+    template = "This is a {foo} test."
+    input_variables = ["bar"]
+    with pytest.raises(ValueError):
+        PromptTemplate(input_variables=input_variables, template=template)
+
+
+def test_prompt_from_examples_valid() -> None:
+    """Test prompt can be successfully constructed from examples."""
+    template = """Test Prompt:
+
+Question: who are you?
+Answer: foo
+
+Question: what are you?
+Answer: bar
+
+Question: {question}
+Answer:"""
+    input_variables = ["question"]
+    example_separator = "\n\n"
+    prefix = """Test Prompt:"""
+    suffix = """Question: {question}\nAnswer:"""
+    examples = [
+        """Question: who are you?\nAnswer: foo""",
+        """Question: what are you?\nAnswer: bar""",
+    ]
+    prompt_from_examples = PromptTemplate.from_examples(
+        examples,
+        suffix,
+        input_variables,
+        example_separator=example_separator,
+        prefix=prefix,
+    )
+    prompt_from_template = PromptTemplate(
+        input_variables=input_variables, template=template
+    )
+    assert prompt_from_examples.template == prompt_from_template.template
+    assert prompt_from_examples.input_variables == prompt_from_template.input_variables
+
+
+def test_prompt_invalid_template_format() -> None:
+    """Test initializing a prompt with invalid template format."""
+    template = "This is a {foo} test."
+    input_variables = ["foo"]
+    with pytest.raises(ValueError):
+        PromptTemplate(
+            input_variables=input_variables, template=template, template_format="bar"
+        )
+
+
+def test_prompt_from_file() -> None:
+    """Test prompt can be successfully constructed from a file."""
+    template_file = "tests/unit_tests/data/prompt_file.txt"
+    input_variables = ["question"]
+    prompt = PromptTemplate.from_file(template_file, input_variables)
+    assert prompt.template == "Question: {question}\nAnswer:"