IBM · MATATAT · Aug 24, 2025 · Aug 24, 2025 · Aug 24, 2025
diff --git a/mocktail-tests/tests/examples/http_unary.rs b/mocktail-tests/tests/examples/http_unary.rs
@@ -184,3 +184,31 @@ async fn test_unary_headers() -> Result<(), Error> {
 
     Ok(())
 }
+
+#[tokio::test]
+async fn test_unary_form_body() -> Result<(), Error> {
+    let mut mocks = MockSet::new();
+    mocks.mock(|when, then| {
+        when.post()
+            .header("content-type", "application/x-www-form-urlencoded")
+            .form(FormBody::new().field("name", "world"));
+        then.text("hello world");
+    });
+
+    let server = MockServer::new_http("form").with_mocks(mocks);
+    server.start().await?;
+
+    let client = reqwest::Client::builder().http2_prior_knowledge().build()?;
+
+    let response = client
+        .post(server.url("/form"))
+        .form(&[("name", "world")])
+        .send()
+        .await?;
+
+    assert_eq!(response.status(), http::StatusCode::OK);
+    let res = response.text().await?;
+    assert_eq!(res, "hello world");
+
+    Ok(())
+}
diff --git a/mocktail/Cargo.toml b/mocktail/Cargo.toml
@@ -28,6 +28,7 @@ prost = "0.14"
 rand = "0.9"
 serde = "1"
 serde_json = "1"
+serde_urlencoded = "0.7"
 thiserror = "2"
 tokio = "1"
 tokio-stream = "0"

diff --git a/mocktail/src/form.rs b/mocktail/src/form.rs
@@ -0,0 +1,50 @@
+use crate::body::Body;
+
+/// The body of a mock request or response as a form.
+#[derive(Debug, Default, Clone, PartialEq, PartialOrd)]
+pub struct FormBody {
+    fields: Vec<(String, String)>,
+}
+
+impl FormBody {
+    /// Creates a new form.
+    pub fn new() -> Self {
+        Self { fields: Vec::new() }
+    }
+
+    /// Creates an empty form.
+    pub fn empty() -> Self {
+        Self::default()
+    }
+
+    /// Adds a field to the form.
+    pub fn field(self, name: impl Into<String>, value: impl Into<String>) -> Self {
+        let mut fields = self.fields;
+
+        fields.push((name.into(), value.into()));
+
+        Self { fields }
+    }
+
+    /// Converts the form body to a URL-encoded string.
+    pub fn url_encoded(&self) -> String {
+        self.fields
+            .iter()
+            .map(|(k, v)| format!("{k}={v}"))
+            .collect::<Vec<_>>()
+            .join("&")
+    }
+}
+
+impl PartialEq<Body> for FormBody {
+    fn eq(&self, other: &Body) -> bool {
+        let mut body_copy = other.clone();
+        let other_form_body =
+            serde_urlencoded::from_bytes::<Vec<(String, String)>>(&body_copy.as_bytes());
+
+        match other_form_body {
+            Ok(other) => self.fields == other,
+            Err(_) => false,
+        }
+    }
+}
diff --git a/mocktail/src/lib.rs b/mocktail/src/lib.rs
@@ -1,5 +1,6 @@
 #![doc = include_str!("../README.md")]
 pub mod body;
+pub mod form;
 mod headers;
 pub use headers::Headers;
 pub mod matchers;
@@ -18,6 +19,7 @@ pub use status::{Code, StatusCode};
 pub mod prelude {
     pub use crate::{
         body::Body,
+        form::FormBody,
         headers::Headers,
         matchers::*,
         mock::Mock,

diff --git a/mocktail/src/matchers.rs b/mocktail/src/matchers.rs
@@ -2,7 +2,7 @@
 use std::{any::Any, borrow::Cow, cmp::Ordering};
 
 use super::{body::Body, headers::Headers, request::Request};
-use crate::request::Method;
+use crate::{form::FormBody, request::Method};
 
 /// A matcher.
 pub trait Matcher: std::fmt::Debug + Send + Sync + 'static + AsMatcherEq {
@@ -97,6 +97,23 @@ pub fn body(body: Body) -> BodyMatcher {
     BodyMatcher(body)
 }
 
+/// Form body matcher.
+#[derive(Debug, PartialEq, PartialOrd)]
+pub struct FormMatcher(FormBody);
+
+impl Matcher for FormMatcher {
+    fn name(&self) -> &str {
+        "form_body"
+    }
+    fn matches(&self, req: &Request) -> bool {
+        self.0 == req.body
+    }
+}
+
+pub fn form(body: FormBody) -> FormMatcher {
+    FormMatcher(body)
+}
+
 /// Headers matcher.
 #[derive(Debug, PartialEq, PartialOrd)]
 pub struct HeadersMatcher(Headers);

diff --git a/mocktail/src/mock_builder/when.rs b/mocktail/src/mock_builder/when.rs
@@ -5,9 +5,9 @@ use bytes::Bytes;
 
 use crate::{
     body::Body,
+    form::FormBody,
     headers::{HeaderName, HeaderValue, Headers},
-    matchers,
-    matchers::Matcher,
+    matchers::{self, Matcher},
     request::Method,
 };
 
@@ -66,6 +66,12 @@ impl When {
         self
     }
 
+    /// Form Body.
+    pub fn form(self, form_body: FormBody) -> Self {
+        self.push(matchers::form(form_body));
+        self
+    }
+
     /// Headers.
     ///
     /// Cannonicalizes passed in header name and values to ensure matching is done in a