Add proxy-prefix and explicitly allow empty proxy values

It's how git does it, and we don't have tests to validate it all.

git-repository/src/repository/config/transport.rs

@@ -131,7 +131,15 @@ impl crate::Repository {
                     opts.proxy = config
                         .string_filter("http", None, "proxy", &mut trusted_only)
                         .and_then(|v| try_cow_to_string(v, lenient, "http.proxy").transpose())
-                        .transpose()?;
+                        .transpose()?
+                        .map(|mut proxy| {
+                            if !proxy.trim().is_empty() && !proxy.contains("://") {
+                                proxy.insert_str(0, "http://");
+                                proxy
+                            } else {
+                                proxy
+                            }
+                        });
                     opts.user_agent = config
                         .string_filter("http", None, "userAgent", &mut trusted_only)
                         .and_then(|v| try_cow_to_string(v, lenient, "http.userAgent").transpose())

git-repository/tests/fixtures/make_config_repos.sh

@@ -10,13 +10,18 @@ git init http-config
   git config http.lowSpeedLimit 5k
   git config http.lowSpeedTime 10
   git config http.postBuffer 8k
-  git config http.proxy localhost:9090
+  git config http.proxy http://localhost:9090
   git config http.proxyAuthMethod anyauth
   git config http.userAgent agentJustForHttp
 )
 
-git init http-config-empty-proxy
-(cd http-config-empty-proxy
+git init http-proxy-empty
+(cd http-proxy-empty
   git config http.proxy localhost:9090
   git config --add http.proxy "" # a value override disabling it later
 )
+
+git init http-proxy-auto-prefix
+(cd http-proxy-auto-prefix
+  git config http.proxy localhost:9090 # http:// is prefixed automatically
+)

git-repository/tests/repository/config/transport_options.rs

@@ -7,13 +7,19 @@ mod http {
         git::open_opts(dir.join(name), git::open::Options::isolated()).unwrap()
     }
 
-    #[test]
-    fn simple_configuration() {
-        let repo = repo("http-config");
-        let http_config = repo
+    fn http_options(repo: &git::Repository) -> git_transport::client::http::Options {
+        let opts = repo
             .transport_options("https://example.com/does/not/matter")
             .expect("valid configuration")
             .expect("configuration available for http");
+        opts.downcast_ref::<git_transport::client::http::Options>()
+            .expect("http options have been created")
+            .to_owned()
+    }
+
+    #[test]
+    fn simple_configuration() {
+        let repo = repo("http-config");
         let git_transport::client::http::Options {
             extra_headers,
             follow_redirects,
@@ -24,25 +30,19 @@ mod http {
             user_agent,
             connect_timeout,
             backend,
-        } = http_config
-            .downcast_ref::<git_transport::client::http::Options>()
-            .expect("http options have been created");
+        } = http_options(&repo);
         assert_eq!(
             extra_headers,
             &["ExtraHeader: value2", "ExtraHeader: value3"],
             "it respects empty values to clear prior values"
         );
         assert_eq!(
-            *follow_redirects,
+            follow_redirects,
             git_transport::client::http::options::FollowRedirects::Initial
         );
-        assert_eq!(*low_speed_limit_bytes_per_second, 5120);
-        assert_eq!(*low_speed_time_seconds, 10);
-        assert_eq!(
-            proxy.as_deref(),
-            Some("localhost:9090"),
-            "TODO: turn it into a URL valid for curl"
-        );
+        assert_eq!(low_speed_limit_bytes_per_second, 5120);
+        assert_eq!(low_speed_time_seconds, 10);
+        assert_eq!(proxy.as_deref(), Some("http://localhost:9090"),);
         assert_eq!(
             proxy_auth_method.as_ref(),
             // Some(&git_transport::client::http::options::ProxyAuthMethod::AnyAuth)
@@ -51,7 +51,7 @@ mod http {
         );
         assert_eq!(user_agent.as_deref(), Some("agentJustForHttp"));
         assert_eq!(
-            *connect_timeout,
+            connect_timeout,
             std::time::Duration::from_secs(20),
             "this is an arbitrary default, and it's her to allow adjustments of the default"
         );
@@ -63,19 +63,21 @@ mod http {
 
     #[test]
     fn empty_proxy_string_turns_it_off() {
-        let repo = repo("http-config-empty-proxy");
+        let repo = repo("http-proxy-empty");
 
-        let http_config = repo
-            .transport_options("https://example.com/does/not/matter")
-            .expect("valid configuration")
-            .expect("configuration available for http");
-        let http_config = http_config
-            .downcast_ref::<git_transport::client::http::Options>()
-            .expect("http options have been created");
+        let opts = http_options(&repo);
         assert_eq!(
-            http_config.proxy.as_deref(),
+            opts.proxy.as_deref(),
             Some(""),
             "empty strings indicate that the proxy is to be unset by the transport"
         );
     }
+
+    #[test]
+    fn proxy_without_protocol_is_defaulted_to_http() {
+        let repo = repo("http-proxy-auto-prefix");
+
+        let opts = http_options(&repo);
+        assert_eq!(opts.proxy.as_deref(), Some("http://localhost:9090"));
+    }
 }