Refactor test 'expect' scripts

Make test 'expect' scripts simpler and ensure expectations are properly
asserted.

Closes #46

tests/expect_successful_update_of_a_single_plugin

@@ -12,50 +12,44 @@ sleep 1
 # this is tmux prefix + U
 send "U"
 
-set timeout 5
+set timeout 15
 
-expect {
-  "Installed plugins" {
-
-    expect {
-      "\"tmux-example-plugin\"" {
-
-        expect {
-          "\"all\" - updates all plugins" {
-
-            expect { "ENTER - cancels" }
-
-          }
-        }
-
-      }
-    }
-
-  }
-
-  timeout {
-    puts "Plugin update prompt timeout";
-    exit 1
-  }
+expect_after {
+  timeout { exit 1 }
 }
 
+expect {
+  "Installed plugins"
+}
+
+expect {
+  "tmux-example-plugin"
+}
+
+expect {
+  "\"all\" - updates all plugins"
+}
+
+expect {
+  "ENTER - cancels"
+}
+
+# wait for tmux to display prompt before sending characters
+sleep 1
 send "tmux-example-plugin\r"
 
 expect {
-  "Updating \"tmux-example-plugin\"" {
+  "Updating \"tmux-example-plugin\""
+}
 
-    expect {
-      "\"tmux-example-plugin\" update success" {
+expect {
+  "\"tmux-example-plugin\" update success"
+}
 
-        expect { "Done, press ENTER to continue." { exit 0 } }
-
-      }
-    }
-
-  }
-
-  timeout {
-    puts "Update all plugins timeout";
-    exit 1
+expect {
+  "Done, press ENTER to continue." {
+    exit 0
   }
 }
+
+exit 1