Spec for from_sql, and a big mock for the DB class (#133)

* Spec for from_sql, and a big mock for the DB class

* Updates to work with sqlite timestamp hack

* cleanup and documentation

spec/granite_orm/querying/from_sql_spec.cr

@@ -0,0 +1,41 @@
+require "../../spec_helper"
+
+macro build_review_emitter(driver)
+  {%
+  timestamp = if driver == "sqlite"
+    "2018-04-09 13:33:46"
+  else
+    "Time.now".id
+  end
+  %}
+
+  FieldEmitter.new.tap do |e|
+    e._set_values(
+      [
+        8_i64,
+        "name",
+        nil,   # downvotes
+        nil,   # upvotes
+        nil,   # sentiment
+        nil,   # interest
+        true,  # published
+        {{ timestamp }} # created_at
+      ]
+    )
+  end
+end
+
+def method_which_takes_any_model(model : Granite::ORM::Base.class)
+  model.as(Granite::ORM::Base).from_sql build_review_emitter
+end
+
+{% for adapter in GraniteExample::ADAPTERS %}
+  module {{ adapter.capitalize.id }}
+    describe "{{ adapter.id }} #from_sql" do
+      it "Builds a model from a resultset" do
+        model = Review.from_sql build_review_emitter({{ adapter }})
+        model.class.should eq Review
+      end
+    end
+  end
+{% end %}

spec/mocks/db_mock.cr

@@ -0,0 +1,89 @@
+class FakeStatement < DB::Statement
+  protected def perform_query(args : Enumerable) : DB::ResultSet
+    FieldEmitter.new
+  end
+
+  protected def perform_exec(args : Enumerable)
+    DB::ExecResult.new 0_i64, 0_i64
+  end
+end
+
+class FakeContext
+  include DB::ConnectionContext
+
+  def uri
+    URI.new ""
+  end
+
+  def prepared_statements?
+    false
+  end
+
+  def discard(connection); end
+  def release(connection); end
+end
+
+class FakeConnection < DB::Connection
+  def initialize
+    @context = FakeContext.new
+    @prepared_statements = false
+  end
+
+  def build_unprepared_statement(query : String)
+    FakeStatement.new self
+  end
+
+  def build_prepared_statement(query : String)
+    FakeStatement.new self
+  end
+end
+
+# FieldEmitter emulates the subtle and uninformed way that
+# DB::ResultSet emits data. To be used in testing interactions
+# with raw data sets.
+class FieldEmitter < DB::ResultSet
+  # 1. Override `#move_next` to move to the next row.
+  # 2. Override `#read` returning the next value in the row.
+  # 3. (Optional) Override `#read(t)` for some types `t` for which custom logic other than a simple cast is needed.
+  # 4. Override `#column_count`, `#column_name`.
+
+  @position = 0
+  @field_position = 0
+  @values = [] of DB::Any
+
+  def initialize
+    @statement = FakeStatement.new FakeConnection.new
+  end
+
+  def _set_values(values : Array(DB::Any))
+    @values = [] of DB::Any
+    values.each do |v|
+      @values << v
+    end
+  end
+
+  def move_next
+    @position += 1
+    @field_position = 0
+  end
+
+  def read
+    if @position >= @values.size
+      raise "Overread"
+    end
+
+
+    @values[@position].tap do |v|
+      @position += 1
+    end
+  end
+
+  def column_count
+    @values.size
+  end
+
+  def column_name(index : Int32)
+    "Column #{index}"
+  end
+end
+

spec/spec_helper.cr

@@ -6,5 +6,6 @@ end
 
 require "../src/granite_orm"
 require "./spec_models"
+require "./mocks/**"
 
 Granite::ORM.settings.logger = ::Logger.new(nil)

spec/spec_models.cr

@@ -204,8 +204,7 @@ end
             sentiment FLOAT,
             interest REAL,
             published BOOL,
-            {{ created_at_sql }},
-            {{ updated_at_sql }}
+            {{ created_at_sql }}
           )
         SQL
       end