diff --git a/core/src/analyzer/blocks.rs b/core/src/analyzer/blocks.rs
index ef83c5d..a157284 100644
--- a/core/src/analyzer/blocks.rs
+++ b/core/src/analyzer/blocks.rs
@@ -128,6 +128,55 @@ fn install_block_parameter(genv: &mut GlobalEnv, lenv: &mut LocalEnv, name: Stri
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::analyzer::install::AstInstaller;
+    use crate::env::LocalEnv;
+    use crate::parser::ParseSession;
+    use crate::types::Type;
+
+    fn get_type_show(genv: &GlobalEnv, vtx: VertexId) -> String {
+        if let Some(vertex) = genv.get_vertex(vtx) {
+            vertex.show()
+        } else if let Some(source) = genv.get_source(vtx) {
+            source.ty.show()
+        } else {
+            panic!("vertex {:?} not found as either Vertex or Source", vtx);
+        }
+    }
+
+    fn analyze_with_stdlib(source: &str) -> GlobalEnv {
+        let session = ParseSession::new();
+        let parse_result = session.parse_source(source, "test.rb").unwrap();
+        let root = parse_result.node();
+        let program = root.as_program_node().unwrap();
+
+        let mut genv = GlobalEnv::new();
+
+        // Register stdlib methods needed for block tests
+        genv.register_builtin_method_with_block(
+            Type::array(),
+            "each",
+            Type::array(),
+            Some(vec![Type::instance("Elem")]),
+        );
+        genv.register_builtin_method_with_block(
+            Type::string(),
+            "each_char",
+            Type::string(),
+            Some(vec![Type::string()]),
+        );
+        genv.register_builtin_method(Type::integer(), "even?", Type::instance("TrueClass"));
+        genv.register_builtin_method(Type::string(), "upcase", Type::string());
+
+        let mut lenv = LocalEnv::new();
+
+        let mut installer = AstInstaller::new(&mut genv, &mut lenv, source);
+        for stmt in &program.statements().body() {
+            installer.install_node(&stmt);
+        }
+        installer.finish();
+
+        genv
+    }
 
     #[test]
     fn test_enter_exit_block_scope() {
@@ -173,4 +222,95 @@ mod tests {
 
         exit_block_scope(&mut genv);
     }
+
+    #[test]
+    fn test_block_parameter_type_from_array() {
+        let source = r#"
+class Foo
+  def bar
+    [1, 2, 3].each { |x| x.even? }
+  end
+end
+"#;
+        let genv = analyze_with_stdlib(source);
+        assert!(
+            genv.type_errors.is_empty(),
+            "x.even? should not produce type errors: {:?}",
+            genv.type_errors
+        );
+        // Verify bar returns Array (each returns its receiver)
+        let info = genv.resolve_method(&Type::instance("Foo"), "bar").unwrap();
+        let ret_vtx = info.return_vertex.unwrap();
+        assert_eq!(get_type_show(&genv, ret_vtx), "Array");
+    }
+
+    #[test]
+    fn test_block_external_variable_access() {
+        let source = r#"
+class Foo
+  def bar
+    y = "hello"
+    [1].each { y.upcase }
+  end
+end
+"#;
+        let genv = analyze_with_stdlib(source);
+        assert!(
+            genv.type_errors.is_empty(),
+            "y.upcase should not produce type errors: {:?}",
+            genv.type_errors
+        );
+    }
+
+    #[test]
+    fn test_block_parameter_from_each_char() {
+        let source = r#"
+class Foo
+  def bar
+    "hello".each_char { |c| c.upcase }
+  end
+end
+"#;
+        let genv = analyze_with_stdlib(source);
+        assert!(
+            genv.type_errors.is_empty(),
+            "c.upcase should not produce type errors: {:?}",
+            genv.type_errors
+        );
+    }
+
+    #[test]
+    fn test_block_body_does_not_affect_method_return() {
+        let source = r#"
+class Foo
+  def bar
+    [1, 2].each { |x| "string" }
+  end
+end
+"#;
+        let genv = analyze_with_stdlib(source);
+        // each returns its receiver (Array), not the block body result (String)
+        let info = genv.resolve_method(&Type::instance("Foo"), "bar").unwrap();
+        let ret_vtx = info.return_vertex.unwrap();
+        assert_eq!(get_type_show(&genv, ret_vtx), "Array");
+    }
+
+    #[test]
+    fn test_nested_blocks() {
+        let source = r#"
+class Foo
+  def bar
+    [1, 2].each { |x|
+      "hello".each_char { |c| c.upcase }
+    }
+  end
+end
+"#;
+        let genv = analyze_with_stdlib(source);
+        assert!(
+            genv.type_errors.is_empty(),
+            "nested block should not produce type errors: {:?}",
+            genv.type_errors
+        );
+    }
 }
diff --git a/core/src/analyzer/parameters.rs b/core/src/analyzer/parameters.rs
index 30dd729..1de2da5 100644
--- a/core/src/analyzer/parameters.rs
+++ b/core/src/analyzer/parameters.rs
@@ -208,6 +208,36 @@ pub(crate) fn install_parameters(
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::analyzer::install::AstInstaller;
+    use crate::parser::ParseSession;
+
+    fn analyze(source: &str) -> GlobalEnv {
+        let session = ParseSession::new();
+        let parse_result = session.parse_source(source, "test.rb").unwrap();
+        let root = parse_result.node();
+        let program = root.as_program_node().unwrap();
+
+        let mut genv = GlobalEnv::new();
+        let mut lenv = LocalEnv::new();
+
+        let mut installer = AstInstaller::new(&mut genv, &mut lenv, source);
+        for stmt in &program.statements().body() {
+            installer.install_node(&stmt);
+        }
+        installer.finish();
+
+        genv
+    }
+
+    fn get_type_show(genv: &GlobalEnv, vtx: VertexId) -> String {
+        if let Some(vertex) = genv.get_vertex(vtx) {
+            vertex.show()
+        } else if let Some(source) = genv.get_source(vtx) {
+            source.ty.show()
+        } else {
+            panic!("vertex {:?} not found as either Vertex or Source", vtx);
+        }
+    }
 
     #[test]
     fn test_install_required_parameter() {
@@ -266,4 +296,134 @@ mod tests {
         let vertex = genv.get_vertex(vtx).unwrap();
         assert_eq!(vertex.show(), "Integer");
     }
+
+    #[test]
+    fn test_required_parameter_type_propagation() {
+        let source = r#"
+class Foo
+  def greet(name)
+    name
+  end
+end
+
+Foo.new.greet("Alice")
+"#;
+        let genv = analyze(source);
+        let info = genv.resolve_method(&Type::instance("Foo"), "greet").unwrap();
+        let ret_vtx = info.return_vertex.unwrap();
+        assert_eq!(get_type_show(&genv, ret_vtx), "String");
+    }
+
+    #[test]
+    fn test_optional_parameter_default_type() {
+        let source = r#"
+class Foo
+  def greet(name = "World")
+    name
+  end
+end
+"#;
+        let genv = analyze(source);
+        let info = genv.resolve_method(&Type::instance("Foo"), "greet").unwrap();
+        let ret_vtx = info.return_vertex.unwrap();
+        assert_eq!(get_type_show(&genv, ret_vtx), "String");
+    }
+
+    #[test]
+    fn test_multiple_parameters_from_call_site() {
+        let source = r#"
+class Calc
+  def add(x, y)
+    x
+  end
+end
+
+Calc.new.add(1, 2)
+"#;
+        let genv = analyze(source);
+        let info = genv.resolve_method(&Type::instance("Calc"), "add").unwrap();
+        let param_vtxs = info.param_vertices.as_ref().unwrap();
+        assert_eq!(param_vtxs.len(), 2);
+        // Verify return type is Integer (method returns x, which receives 1)
+        let ret_vtx = info.return_vertex.unwrap();
+        assert_eq!(get_type_show(&genv, ret_vtx), "Integer");
+    }
+
+    #[test]
+    fn test_keyword_parameter_propagation() {
+        let source = r#"
+class Foo
+  def greet(name:)
+    name
+  end
+end
+
+Foo.new.greet(name: "Alice")
+"#;
+        let genv = analyze(source);
+        let info = genv.resolve_method(&Type::instance("Foo"), "greet").unwrap();
+        let ret_vtx = info.return_vertex.unwrap();
+        assert_eq!(get_type_show(&genv, ret_vtx), "String");
+    }
+
+    #[test]
+    fn test_optional_keyword_parameter_default() {
+        let source = r#"
+class Counter
+  def count(step: 1)
+    step
+  end
+end
+"#;
+        let genv = analyze(source);
+        let info = genv.resolve_method(&Type::instance("Counter"), "count").unwrap();
+        let ret_vtx = info.return_vertex.unwrap();
+        assert_eq!(get_type_show(&genv, ret_vtx), "Integer");
+    }
+
+    #[test]
+    fn test_mixed_positional_and_keyword_params() {
+        let source = r#"
+class User
+  def initialize(id, name:)
+    @id = id
+    @name = name
+  end
+end
+
+User.new(1, name: "Alice")
+"#;
+        let genv = analyze(source);
+        assert!(genv.type_errors.is_empty());
+    }
+
+    #[test]
+    fn test_rest_parameter() {
+        let source = r#"
+class Foo
+  def bar(*args)
+    args
+  end
+end
+"#;
+        let genv = analyze(source);
+        let info = genv.resolve_method(&Type::instance("Foo"), "bar").unwrap();
+        let ret_vtx = info.return_vertex.unwrap();
+        assert_eq!(get_type_show(&genv, ret_vtx), "Array");
+    }
+
+    #[test]
+    fn test_no_parameters() {
+        let source = r#"
+class Foo
+  def bar
+    "hello"
+  end
+end
+"#;
+        let genv = analyze(source);
+        let info = genv.resolve_method(&Type::instance("Foo"), "bar").unwrap();
+        let param_vtxs = info.param_vertices.as_ref().unwrap();
+        assert!(param_vtxs.is_empty());
+    }
 }