Add initial integration style tests (#20)

Signed-off-by: José Ulises Niño Rivera <junr03@users.noreply.github.com>

envoyfilter/tests/integration.rs

@@ -0,0 +1,92 @@
+use proxy_wasm_test_framework::tester;
+use proxy_wasm_test_framework::types::{Action, BufferType, MapType, MetricType, ReturnType};
+use std::path::Path;
+
+fn wasm_module() -> String {
+    let wasm_file = Path::new("target/wasm32-wasi/release/intelligent_prompt_gateway.wasm");
+    assert!(
+        wasm_file.exists(),
+        "Run `cargo build --release --target=wasm32-wasi` first"
+    );
+    wasm_file.to_str().unwrap().to_string()
+}
+
+#[test]
+fn request_to_open_ai_chat_completions() {
+    let args = tester::MockSettings {
+        wasm_path: wasm_module(),
+        quiet: false,
+        allow_unexpected: false,
+    };
+    let mut module = tester::mock(args).unwrap();
+
+    module
+        .call_start()
+        .execute_and_expect(ReturnType::None)
+        .unwrap();
+
+    // Setup Filter
+    let root_context = 1;
+
+    module
+        .call_proxy_on_context_create(root_context, 0)
+        .expect_metric_creation(MetricType::Gauge, "active_http_calls")
+        .execute_and_expect(ReturnType::None)
+        .unwrap();
+
+    // Setup HTTP Stream
+    let http_context = 2;
+
+    module
+        .call_proxy_on_context_create(http_context, root_context)
+        .execute_and_expect(ReturnType::None)
+        .unwrap();
+
+    // Request Headers
+    module
+        .call_proxy_on_request_headers(http_context, 0, false)
+        .expect_get_header_map_value(Some(MapType::HttpRequestHeaders), Some(":host"))
+        .returning(Some("api.openai.com"))
+        .expect_add_header_map_value(
+            Some(MapType::HttpRequestHeaders),
+            Some("content-length"),
+            Some(""),
+        )
+        .expect_get_header_map_value(Some(MapType::HttpRequestHeaders), Some(":path"))
+        .returning(Some("/llmrouting"))
+        .expect_add_header_map_value(
+            Some(MapType::HttpRequestHeaders),
+            Some(":path"),
+            Some("/v1/chat/completions"),
+        )
+        .execute_and_expect(ReturnType::Action(Action::Continue))
+        .unwrap();
+
+    // Request Body
+    let chat_completions_request_body = "\
+    {\
+        \"messages\": [\
+        {\
+            \"role\": \"system\",\
+            \"content\": \"You are a poetic assistant, skilled in explaining complex programming concepts with creative flair.\"\
+        },\
+        {\
+            \"role\": \"user\",\
+            \"content\": \"Compose a poem that explains the concept of recursion in programming.\"\
+        }\
+        ]\
+    }";
+
+    module
+        .call_proxy_on_request_body(
+            http_context,
+            chat_completions_request_body.len() as i32,
+            true,
+        )
+        .expect_get_buffer_bytes(Some(BufferType::HttpRequestBody))
+        .returning(Some(chat_completions_request_body))
+        // TODO: assert that the model field was added.
+        .expect_set_buffer_bytes(Some(BufferType::HttpRequestBody), None)
+        .execute_and_expect(ReturnType::Action(Action::Continue))
+        .unwrap();
+}