Add Lint/AmbiguousAssignment rule (#244)

spec/ameba/ast/util_spec.cr

@@ -44,7 +44,7 @@ module Ameba::AST
         )
         node = Crystal::Parser.new(s).parse
         source = subject.node_source node, s.split("\n")
-        source.should eq ["a = 1"]
+        source.should eq "a = 1"
       end
 
       it "returns original source of multiline node" do
@@ -55,11 +55,11 @@ module Ameba::AST
         )
         node = Crystal::Parser.new(s).parse
         source = subject.node_source node, s.split("\n")
-        source.should eq([
-          "if ()",
-          "            :ok",
-          "          end",
-        ])
+        source.should eq <<-CRYSTAL
+          if ()
+                      :ok
+                    end
+          CRYSTAL
       end
 
       it "does not report source of node which has incorrect location" do
@@ -81,7 +81,7 @@ module Ameba::AST
         if SemanticVersion.parse(Crystal::VERSION) <= SemanticVersion.parse("0.35.1")
           source.should be_nil
         else
-          source.should eq %w(nil)
+          source.should eq "nil"
         end
       end
     end

spec/ameba/rule/lint/ambiguous_assignment_spec.cr

@@ -0,0 +1,169 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Lint
+  describe AmbiguousAssignment do
+    subject = AmbiguousAssignment.new
+
+    context "when using `-`" do
+      it "registers an offense with `x`" do
+        source = Source.new("x =- y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `-=`?"
+        issue.location.to_s.should eq "source.cr:1:3"
+        issue.end_location.to_s.should eq "source.cr:1:4"
+      end
+
+      it "registers an offense with `@x`" do
+        source = Source.new("@x =- y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `-=`?"
+        issue.location.to_s.should eq "source.cr:1:4"
+        issue.end_location.to_s.should eq "source.cr:1:5"
+      end
+
+      it "registers an offense with `@@x`" do
+        source = Source.new("@@x =- y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `-=`?"
+        issue.location.to_s.should eq "source.cr:1:5"
+        issue.end_location.to_s.should eq "source.cr:1:6"
+      end
+
+      it "registers an offense with `X`" do
+        source = Source.new("X =- y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `-=`?"
+        issue.location.to_s.should eq "source.cr:1:3"
+        issue.end_location.to_s.should eq "source.cr:1:4"
+      end
+
+      it "does not register an offense when no mistype assignments" do
+        subject.catch(Source.new(<<-CRYSTAL)).should be_valid
+          x = 1
+          x -= y
+          x = -y
+        CRYSTAL
+      end
+    end
+
+    context "when using `+`" do
+      it "registers an offense with `x`" do
+        source = Source.new("x =+ y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `+=`?"
+        issue.location.to_s.should eq "source.cr:1:3"
+        issue.end_location.to_s.should eq "source.cr:1:4"
+      end
+
+      it "registers an offense with `@x`" do
+        source = Source.new("@x =+ y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `+=`?"
+        issue.location.to_s.should eq "source.cr:1:4"
+        issue.end_location.to_s.should eq "source.cr:1:5"
+      end
+
+      it "registers an offense with `@@x`" do
+        source = Source.new("@@x =+ y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `+=`?"
+        issue.location.to_s.should eq "source.cr:1:5"
+        issue.end_location.to_s.should eq "source.cr:1:6"
+      end
+
+      it "registers an offense with `X`" do
+        source = Source.new("X =+ y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `+=`?"
+        issue.location.to_s.should eq "source.cr:1:3"
+        issue.end_location.to_s.should eq "source.cr:1:4"
+      end
+
+      it "does not register an offense when no mistype assignments" do
+        subject.catch(Source.new(<<-CRYSTAL)).should be_valid
+          x = 1
+          x += y
+          x = +y
+        CRYSTAL
+      end
+    end
+
+    context "when using `!`" do
+      it "registers an offense with `x`" do
+        source = Source.new("x =! y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `!=`?"
+        issue.location.to_s.should eq "source.cr:1:3"
+        issue.end_location.to_s.should eq "source.cr:1:4"
+      end
+
+      it "registers an offense with `@x`" do
+        source = Source.new("@x =! y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `!=`?"
+        issue.location.to_s.should eq "source.cr:1:4"
+        issue.end_location.to_s.should eq "source.cr:1:5"
+      end
+
+      it "registers an offense with `@@x`" do
+        source = Source.new("@@x =! y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `!=`?"
+        issue.location.to_s.should eq "source.cr:1:5"
+        issue.end_location.to_s.should eq "source.cr:1:6"
+      end
+
+      it "registers an offense with `X`" do
+        source = Source.new("X =! y", "source.cr")
+        subject.catch(source).should_not be_valid
+        source.issues.size.should eq 1
+
+        issue = source.issues.first
+        issue.message.should eq "Suspicious assignment detected. Did you mean `!=`?"
+        issue.location.to_s.should eq "source.cr:1:3"
+        issue.end_location.to_s.should eq "source.cr:1:4"
+      end
+
+      it "does not register an offense when no mistype assignments" do
+        subject.catch(Source.new(<<-CRYSTAL)).should be_valid
+          x = false
+          x != y
+          x = !y
+        CRYSTAL
+      end
+    end
+  end
+end