[gosrc2cpg] AST Creation and Dataflow tests segregation (#3513)

The `ASTCreationsPassTests.scala` file contained all kinds of tests, that were difficult to track. This PR segregates contents of `ASTCreationsPassTests.scala` into concise test-case files.

joern-cli/frontends/gosrc2cpg/src/test/scala/io/joern/go2cpg/dataflow/ConditionalsDataflowTests.scala

@@ -0,0 +1,94 @@
+package io.joern.go2cpg.dataflow
+
+import io.joern.go2cpg.testfixtures.GoCodeToCpgSuite
+import io.shiftleft.semanticcpg.language._
+import io.joern.dataflowengineoss.language._
+import io.joern.go2cpg.testfixtures.GoCodeToCpgSuite
+
+class ConditionalsDataflowTests extends GoCodeToCpgSuite(withOssDataflow = true) {
+  "Source to sink dataflow through if blocks" should {
+
+    "be reachable (case 1)" in {
+      val cpg = code("""
+          |package main
+          |func main(){
+          |   var a int = 4
+          |   var b int
+          |   if (a > 6) {
+          |     c := a
+          |     b = c
+          |   }
+          |}
+          |
+          |""".stripMargin)
+      val source = cpg.identifier("a").lineNumber(4)
+      val sink   = cpg.identifier("b").lineNumber(8)
+      sink.reachableByFlows(source).size shouldBe 1
+
+    }
+
+    "be reachable (case 2)" in {
+      val cpg = code("""
+          |package main
+          |func main(){
+          |   var a int = 4
+          |   var b int
+          |   if (a > 6) {
+          |     b = a
+          |   }else {
+          |      c := a
+          |      b = c
+          |   }
+          |}
+          |
+          |""".stripMargin)
+      val source = cpg.identifier("a").lineNumber(4)
+      val sink   = cpg.identifier("b").lineNumber(10)
+      sink.reachableByFlows(source).size shouldBe 1
+
+    }
+
+    "be reachable (case 3)" in {
+      val cpg = code("""
+          |package main
+          |func main(){
+          |   var a int = 4
+          |   var b int
+          |   if (a > 6) {
+          |     b = a
+          |   }else if (a < 4) {
+          |      c := a
+          |      b = c
+          |   }else {
+          |      b = a
+          |   }
+          |}
+          |
+          |""".stripMargin)
+      val source = cpg.identifier("a").lineNumber(4)
+      val sink   = cpg.identifier("b").lineNumber(10)
+      sink.reachableByFlows(source).size shouldBe 1
+
+    }
+
+    "be reachable (case 4)" in {
+      val cpg = code("""
+          |package main
+          |func main(){
+          |   var a int = 4
+          |   var b int
+          |   if (a > 6) {
+          |     if (a < 10) {
+          |       c := a
+          |       b = c
+          |     }
+          |   }
+          |}
+          |
+          |""".stripMargin)
+      val source = cpg.identifier("a").lineNumber(4)
+      val sink   = cpg.identifier("b").lineNumber(9)
+      sink.reachableByFlows(source).size shouldBe 1
+    }
+  }
+}

joern-cli/frontends/gosrc2cpg/src/test/scala/io/joern/go2cpg/dataflow/LoopsDataflowTests.scala

@@ -0,0 +1,56 @@
+package io.joern.go2cpg.dataflow
+
+import io.joern.go2cpg.testfixtures.GoCodeToCpgSuite
+import io.shiftleft.semanticcpg.language._
+import io.joern.dataflowengineoss.language._
+import io.joern.go2cpg.testfixtures.GoCodeToCpgSuite
+
+class LoopsDataflowTests extends GoCodeToCpgSuite(withOssDataflow = true) {
+  "Source and sink dataflow for for loop" should {
+    "be reachable when initialization, condition and post step are present" in {
+      val cpg = code("""
+          |package main
+          |func main() {
+          |   var b int = 10
+          |
+          |   /* for loop execution */
+          |   for a := 0; a < 10; a++ {
+          |       b += a
+          |   }
+          |
+          |   z := b
+          |}
+    """.stripMargin)
+      val source1 = cpg.identifier("b").lineNumber(4).l
+      val sink1   = cpg.identifier("z").l
+      sink1.reachableByFlows(source1).size shouldBe 1
+
+      val source2 = cpg.identifier("b").lineNumber(8).l
+      val sink2   = cpg.identifier("z").l
+      sink2.reachableByFlows(source2).size shouldBe 1
+    }
+
+    // TODO Looks like some issue due to `range` being a unaryExpr here
+    "be reachable for range statement" ignore {
+      val cpg = code("""package main
+          |func main() {
+          |   var message string = "Hello, Gophers!"
+          |
+          |   counter := 0
+          |   for index, char := range message {
+          |        counter += index
+          |    }
+          |    indexSum := counter
+          |}
+          |""".stripMargin)
+      val source1 = cpg.identifier("counter").lineNumber(5).l
+      val sink1   = cpg.identifier("z").l
+      sink1.reachableByFlows(source1).size shouldBe 1
+
+      val source2 = cpg.identifier("counter").lineNumber(7).l
+      val sink2   = cpg.identifier("indexSum").l
+      sink2.reachableByFlows(source2).size shouldBe 1
+
+    }
+  }
+}