Add documentation for reading variables from environment variables #409…

… and also to override the definition of a variable in a config file #410

_data/documentation.yml

@@ -109,6 +109,7 @@
 - title: Global variables
   docs:
   - variable-define
+  - variable-override
 
 - title: Metadata
   docs:

_documentation/metadata-concept.md

@@ -1,7 +1,7 @@
 ---
 layout: documentation
 title: Concept of metadata
-prev_section: variable-define
+prev_section: variable-override
 next_section: metadata-description
 permalink: /docs/metadata-concept/
 ---

_documentation/variable-define.md

@@ -2,7 +2,7 @@
 layout: documentation
 title: Define variables
 prev_section: config-traces-debugging
-next_section: metadata-concept
+next_section: variable-override
 permalink: /docs/variable-define/
 ---
 Version 1.17 has introduced the notion of *variable*. A variable is a scalar-value (a unique value, not a list of a result-set) that can be reused in different places of your test-suites. another big advantage of variables is that they are evaluated during the test-suite execution. Suppose that you have a query expecting a date as a parameter and that you want to specify the current date: without a variable, it's not possible!
@@ -26,25 +26,57 @@ The variables are defined at the top of the test-suite (after *settings* but bef
   </variables>
 {% endhighlight %}
 
-As you can understand fom the fragment above, a variable can be evaluated based on two engines: *C#* and *query-scalar*
+As you can understand fom the fragment above, a variable can be evaluated based on different engines.
 
 ## C# engine
 
 This engine evaluates one unique sentence of C# and returns the corresponding value. In order to specify this engine use the element *script* and specify the attribute *language* to the value *c-sharp*. Then you'll be ableto specify your c# sentence in the inner text of this element. Note that thsi sentence shouldn't start by *return* and neither end by a semi-column (;).
 
+In this example, the variable named *FirstOfCurrentMonth* is set to the value returned by the C# script:
+
+{% highlight xml %}
+<variable name="FirstOfCurrentMonth">
+  <script language="c-sharp">
+    DateTime.Now.AddDays(1 - DateTime.Now.Day)
+  </script>
+</variable>
+{% endhighlight %}
+
 ## Query engine
 
 This engine evaluates a query and returns the first cell of the first row returned by this query. In order to specify this engine use the element *query-scalar* and specify. Then you'll be able to specify a query with the different methods available in the [NBi syntax 2.0 to define a query](../docs/syntax-2-0).
 
+In this example, the variable named *CurrencyCode* is set to the single value returned by the query here under:
+
+{% highlight xml %}
+<variable name="CurrencyCode">
+  <query-scalar>
+    <![CDATA[select top(1) CurrencyCode from [Sales].[Currency] where Name like '%Canad%']]>
+  </query-scalar>
+</variable>
+{% endhighlight %}
+
+## Environment variable
+
+This engine retrieves the value of an environment variable.
+
+In this example, the variable named *myVar* is set to the value of the environment variable named *MyEnvVar*:
+
+{% highlight xml %}
+<variable name="myVar"/>
+  <environment name="MyEnvVar"/>
+</variable>
+{% endhighlight %}
+
 # Usage
 
 In this first release, you can't use the variables at many places. the usage is strictly limited to the following places:
 
 * *[Parameter](..docs/query-parameter)* (of a query)
 * In the [comparisons (*equal*, *more-than*, *less-than*)](../docs/resultset-rows-count) for a *row-count*
-* In the [predicates](../docs/resultset-predicate) of the assertions *row-count*, *all-rows*, *no-rows*, *some-rows* and *single-row*
+* In the operators of [predicates](../docs/resultset-predicate) of the assertions *row-count*, *all-rows*, *no-rows*, *some-rows* and *single-row*
 
-If you've other places, where you think that a variable would be helpful, report it by creating an [issues](http://github.com/Seddryck/nbi/issues)
+If you've other places, where you think that a variable would be helpful, report it by creating an [issue](http://github.com/Seddryck/nbi/issues)
 
 # Notes about the future of variables
 

_documentation/variable-override.md

@@ -0,0 +1,21 @@
+---
+layout: documentation
+title: Override variables
+prev_section: variable-define
+next_section: metadata-concept
+permalink: /docs/variable-override/
+---
+Version 1.19 introduces the notion of *override* in a *variable*. This option offers the opportunity to enforce the value of a *variable* using a config file.
+
+# Config file
+
+To enforce the value of one or more variables, you must enlist them in the *variables* element of the config file. The attribute *name* specifies the name of the overriden variable, the attribute *value* specifies the value to apply to this variable and finally the attribute *type* sepcifies the type of the variable (could be *text*, *numeric*, *dateTime* or *boolean*).
+
+{% highlight xml %}
+<nbi ...>
+   <variables>
+      <add name="myDate" value="2013-12-01" type="DateTime"/>
+      <add name="myNum" value="187" type="Numeric"/>
+   </variables>
+</nbi>
+{% endhighlight %}