Feature: Template Renderer Error Handling and Edge Cases

  Scenario Outline: Template renderer initialization failures for missing packages
    Given I try to initialize a TemplateRenderer with the "<engine>" engine
    When the required package "<package>" is not installed
    Then a TemplateError should be raised with a message containing "<message>"

    Examples:
      | engine   | package  | message                                                    |
      | jinja2   | jinja2   | Jinja2 is not installed. Install it with 'pip install jinja2'. |
      | mustache | pystache | Pystache is not installed. Install it with 'pip install pystache'. |

  Scenario: Template renderer initialization with unsupported engine
    Given I have an unsupported template engine type
    When I try to initialize a TemplateRenderer with this engine type
    Then a TemplateError should be raised with a message containing "Unsupported template engine"

  Scenario: Registering a template with an empty name
    Given a TemplateRenderer with the "simple" engine
    When I attempt to register a template with an empty name
    Then a TemplateError should be raised with a message containing "Template name cannot be empty"

  Scenario: Registering an invalid Jinja2 template
    Given a TemplateRenderer with the "jinja2" engine
    When I try to register a template with invalid Jinja2 syntax "Hello, {{ name"
    Then a TemplateError should be raised with a message containing "Failed to register Jinja2 template 'invalid'"

  Scenario: Rendering a simple template with missing format variables
    Given a TemplateRenderer with the "simple" engine
    And a template named "test" with content "Hello, {name}"
    When I try to render the "test" template with an empty context
    Then a TemplateError should be raised with a message containing "Missing template variable: name"

  Scenario: Rendering a simple string with missing format variables
    Given a TemplateRenderer with the "simple" engine
    When I try to render the string "Hello, {name}" with an empty context
    Then a TemplateError should be raised with a message containing "Missing template variable: name"

  Scenario: Rendering a simple template with a placeholder evaluating to None
    Given a TemplateRenderer with the "simple" engine
    And a template named "test" with content "Value: {{novalue}}"
    When I render the "test" template with context '{"novalue": null}'
    Then the result should be "Value: "

  Scenario: Rendering a simple template with an invalid expression
    Given a TemplateRenderer with the "simple" engine
    And a template named "test" with content "Value: {{ 1 +/ 2 }}"
    When I try to render the "test" template with any context
    Then a TemplateError should be raised with a message containing "Failed to render template 'test'"

  Scenario: Rendering a simple string with an invalid expression
    Given a TemplateRenderer with the "simple" engine
    When I try to render the string "Value: {{ 1 +/ 2 }}" with any context
    Then a TemplateError should be raised with a message containing "Failed to render template string"

  Scenario: Getting a non-existent template
    Given a TemplateRenderer with the "simple" engine
    When I try to get a template named "nonexistent"
    Then a TemplateError should be raised with a message containing "Template 'nonexistent' not found"

  Scenario: Rendering a non-existent template
    Given a TemplateRenderer with the "simple" engine
    When I try to render a template named "nonexistent" with any context
    Then a TemplateError should be raised with a message containing "Template 'nonexistent' not found"

  Scenario: Registration failure with Jinja2 due to bad engine object
    Given a TemplateRenderer with the "jinja2" engine
    And I have manually modified the engine to be invalid
    When I try to register a template named "test" with content "Hello"
    Then a TemplateError should be raised with a message containing "Jinja2 environment has no from_string method"

  Scenario: Rendering failure with Jinja2 due to bad template object
    Given a TemplateRenderer with the "jinja2" engine
    And I have manually registered a template named "bad_template" that is not a valid Jinja2 template object
    When I try to render the "bad_template" template with any context
    Then a TemplateError should be raised with a message containing "Jinja2 template has no render method"

  Scenario: String rendering failure with Jinja2 due to bad engine object
    Given a TemplateRenderer with the "jinja2" engine
    And I have manually modified the engine to be invalid
    When I try to render the string "Hello, {{name}}" with any context
    Then a TemplateError should be raised with a message containing "Jinja2 environment has no from_string method"

  Scenario: Rendering failure with Mustache due to bad engine object
    Given a TemplateRenderer with the "mustache" engine
    And I have manually modified the engine to be invalid
    And a template named "test" with content "Hello, {{name}}"
    When I try to render the "test" template with any context
    Then a TemplateError should be raised with a message containing "Mustache renderer has no render method"

  Scenario: String rendering failure with Mustache due to bad engine object
    Given a TemplateRenderer with the "mustache" engine
    And I have manually modified the engine to be invalid
    When I try to render the string "Hello, {{name}}" with any context
    Then a TemplateError should be raised with a message containing "Mustache renderer has no render method"

  Scenario: Rendering with an unsupported engine type
    Given a TemplateRenderer with the "simple" engine
    And I have manually set the engine type to an unsupported value
    And a template named "test" with content "Hello"
    When I try to render the "test" template with any context
    Then a TemplateError should be raised with a message containing "Unsupported template engine"

  Scenario: String rendering with an unsupported engine type
    Given a TemplateRenderer with the "simple" engine
    And I have manually set the engine type to an unsupported value
    When I try to render the string "Hello" with any context
    Then a TemplateError should be raised with a message containing "Unsupported template engine"